LOSE 10.6 POUNDS in FOUR WEEKS with this ONE WEIRD TRICK Discovered by Local Slime Hive Mind! Doctors GRUDGINGLY RESPECT Them, Hope to Become Friends

The first time we mentioned the potato diet, in Part III of our series A Chemical Hunger, we shared the story of Chris Voigt, the Executive Director of the Washington State Potatoes Commission, who lost 21 pounds on a 60-day potato diet. By Part X of the series, we started to wonder if someone should maybe run a study, and see if the potato diet really works as well as all that. 

For those of you who are just joining us, the potato diet is a diet where you try to get most of your calories (>95%) from potatoes. You can have drinks like coffee and tea. You can season the potatoes with salt, spices, and whatever hot sauce you want. You can even cook with oil. The only thing we asked people to entirely avoid was dairy (see original post for details). 

Does this mean you can eat fries for every meal? It does, and some people came pretty close to that ideal. See for example, this post:

I have never heard of a diet that allows you to eat french fries for all three meals, and I did just that on a couple of days. It rocked.

Or:

But we’re getting ahead of ourselves.

1. Background

We announced the first Potato Diet Community Trial on April 29th 2022, in a post titled, “Potato Diet Community Trial: Sign up Now, lol”. We announced the trial on twitter, and on the SSC/ACX subreddit. Signups opened the same day. We asked people to try the diet for four weeks

As people signed up and started sharing their experiences, we made a twitter thread of live-ish updates. In this thread you can read anecdotes shared on twitter that aren’t found in the official study data.

To sign up for the study, participants filled out a google form (PDF available in the repository; see below) of demographic information, then over the next four weeks, recorded their data on a copy of a google sheet that we provided.

Two hundred and twenty people filled out the signup form before we closed the study. As far as we can tell, most signups came from twitter, reddit, and word-of-mouth. We actually didn’t ask about this, probably should have. Whoops.

Signups closed on June 3rd, 2022, four weeks after we announced the diet.

We downloaded people’s data when they sent us an email to formally close the study. Anyone who didn’t send us an email to officially close the study, we grabbed their data (if any) in the last days before closing the study. The dataset we’ll be examining today represents the state of the data as of midnight on Friday, July 1st, 2022, four weeks after we closed signups and eight weeks after we started collecting data.

Raw data, the analysis script, and study materials are available on the OSF. We decided to store our data and materials there, since that repository is well-supported and we expect it to stay available for a long time. The organized data is “SMTM Potato Diet Community Trial Main Form.csv”; the script is called “SMTM Potato Diet Community Trial 1 Analysis.R”; and the raw data is in a folder called “Potato Raw Dato” 

This dataset is very rich — we certainly haven’t found everything there is to find in these data. A number of people measured other variables (like blood pressure, resting heart rate, and sleep) and we haven’t looked at those data in any systematic way.

Also there is a lot of room for new findings in coding the free-response data. You could, for example, go through and try to code what kind of oil(s) people are using, and see if people who use different oils lose different amounts of weight, find the diet easier, etc.

We really look forward to seeing other people do their own analyses. Send them our way, we’ll link them or do a roundup post or a meta-analysis or something.  

Two participants asked that we not share their data publicly. But if you’re following along at home you should still get the same results as we do, because those two participants seem to have entered no data.

If you have advice about what to do differently next time, we are interested in hearing that. But if you don’t like something about the study design and just want to gripe — run your own study!

2. Variables

Let’s start with a recap of the study variables.

Our demographic variables are — age, ethnicity, height in inches, local ZIP or postal code, current country of residence, profession, and reported sex. 

Sex was initially reported as “Male”, “Female”, or a free-response “other” field. A few participants reported being trans or nonbinary, so we created two variables, “Chromosomal Sex (estimated)” and “Hormonal Profile (estimated)” where we estimated their chromosomal sex and hormonal profile, respectively, based off of free report data. As the names suggest, these are just estimates. We don’t actually have access to your chromosomes.

This is in case there end up being major endocrinological effects. It seems like there could be sex differences in the potato diet because there are clear sex differences in obesity and in anorexia, which we think may be related.

On their datasheets, participants were asked to record a slate of variables every day. Our main daily variables are — daily weight in pounds; notes for each day; energy for each day on a scale from 1-7, where higher numbers are more energy; mood for each day on a scale from 1-7, where higher numbers are a better mood; and ease of the diet for each day on a scale from 1-7, where higher numbers are finding the diet easier.

We also had a field where participants could record whether or not they broke the diet (eating something substantial other than potatoes) each day. If they stuck to the diet we asked them to put a 0 in this field, if they broke the diet we asked them to put a 1. This is a bit of a mouthful so we will often colloquially refer to these as “cheat days”.

3. Demographics

A total of 220 people submitted the initial form.

Of those, 11 people filled out the signup form incorrectly in such a way that we couldn’t sign them up (they didn’t enter an email, didn’t indicate critical data such as height, etc.). We enrolled the remaining 209 people in the study.

Let’s take a look at the demographics of the people who enrolled: 

  • Age ranged from 18 to 69, with a mean of 35.2 and a median of 35. 
  • Reported sex was 50 female, 151 male, 7 other entries (e.g. “non-binary”, “AFAB on testosterone so idk how you wanna categorise that”), and one person who didn’t respond.
  • Based on this, we estimated 51 XX participants and 156 XY participants; and we estimated 53 people with a more “female” hormonal profile and 153 people with a more “male” hormonal profile.
  • Reported ethnicity was 185 white, 10 Asian, 2 Indian, and 4 more specific entries (e.g. Latin, Indonesian, etc.). Everyone else who reported ethnicity reported being a mix (e.g. “Brazilian. Mostly white, kinda mixed though.”; “German/Vietnamese/Anglo-Saxon“).
  • Participants mostly came from the Anglosphere and Europe: 133 US, 17 UK, 17 Canada, 7 Germany, 6 Australia, 4 Ireland, 3 Sweden, 2 Poland, 2 India, 2 Hungary, 2 France, and several singletons from places like Finland, Mexico, Serbia, Brazil, and “Magyarorsz√°g” [sic] which we think is also Hungary.
  • Profession is hard to code since it’s so diverse, but it looks like the biggest groups were software engineers/programmers, grad students, various scientists and academics, and game designers.

Out of the 209 people signed up, 5 started the diet late for one reason or another, and were still in the middle of the four weeks when we closed data collection on July 1st. We let them keep going and looked at the 204 people remaining.

Of these 204 participants, 44 never entered any data onto their datasheet. As far as we can tell, they just never got around to starting the diet — we certainly didn’t get any data from them.

This leaves us with a total of 160 people who entered some data. Of those 160:

  • Age ranged from 19 to 61, with a mean of 36.0 and a median of 35.5. 
  • Reported sex was 29 female, 124 male, 6 other entries, and one person who didn’t respond.
  • Based on this, we estimated 30 XX participants and 129 XY participants; and we estimated 32 people with a more “female” hormonal profile and 126 people with a more “male” hormonal profile.
  • Reported ethnicity was 145 white, 5 Asian, and 10 other entries like “Polish” or “Japanese/ Hispanic”.
  • Participants were still largely Americans: 104 US, 13 Canada, 12 UK, 6 Germany, 5 Australia, 3 Sweden, 2 Poland, 2 Ireland, 2 Hungary, and one each to a number of others.
  • Again the most common profession is software engineer / programmer, with various research jobs and IT jobs behind it.

Of this group, 35 people formally closed the diet early by sending us an email. We coded the reason they dropped out based on their comments.

One we coded as dropping out because of boredom (“Overall not a difficult diet, but I decided to end it because I was getting pretty bored of potatoes.”).

Two reported stopping because they got sick, which we coded as illness. This isn’t potato-related illness, to be clear — one had a throat infection and the other got shingles.

Six reported stopping because of a schedule conflict, coded as schedule. Some of them specifically said they could have kept going otherwise, like participant 66959098: 

I am ending my diet at 21 days instead of at 28. This is mostly a scheduling issue, having family visiting next week and would like to go out and eat with them. I believe I could have made the four weeks without too much trouble otherwise, and I may even go back on the diet again sometime later. 

The remaining 27 early closures reported stopping because they found the diet really difficult in one way or another, and we coded this as difficulty. For example, participant 29957259: 

I threw in the towel on the potato diet six days in. The first few days were easy for me, but it eventually grew much more difficult. I found myself thinking about food way more than someone whose next meal was planned should have.

Clearly the potato diet really does not work for some people! More on this later.

Another 57 people made it partway to 4 weeks but didn’t officially close the study, and we don’t know why. We went back and forth on what to call this, since we don’t know why they stopped reporting their data, and we wanted the coding to sound as neutral as possible. In the end we coded them as dropped

These participants don’t seem to have just flaked out. Many of them made it a long way. Several people made it past two weeks, and two people made it all the way to day 27:

We’re going to try to stay agnostic about what happened in these cases, because these participants didn’t give us a clear reason why they dropped out. But we can also make some educated guesses. 

Some people clearly dropped out because the diet was too difficult. For example, participant 31554252’s last comment was: 

Finding it very difficult to keep going—just very sick of potatoes

But other people don’t seem to have found the diet difficult, and probably dropped out for other reasons. For example, participant 71309629 appears to have dropped out because of illness. They said, “Got sick, will update later” on the last day they entered data, and haven’t updated since. We hope you’re ok!

Similarly, participant 97388755 could probably be coded as ending for schedule reasons. She said in the comments:

I renounce potato. I’m moving house and the chocolate cravings and trying to make potatoes for 2 people is a pain in the ass.

It might be interesting to go back and try to re-code all the dropped trials, figure out why they stopped the diet, but not today.

Since we asked everyone how easy the diet was, we can also look at the ease they reported on the last day they gave us a weight measurement (though a few people stopped reporting ease before then). As a reminder, higher numbers / more to the right is more easy:

Some people definitely were finding this difficult when they stopped, and it’s reasonable to think that the people who gave a 1 or 2 on the last day stopped because they couldn’t stand it.

But plenty of people who dropped out without telling us why rated diet ease at a 6 or a 7. The modal value is clearly 5! So while some of these dropped trials are because of difficulty, others presumably dropped out for other reasons: they had to go on a trip, they had a family emergency, they got sick with COVID, etc.

The diet protocol in the original post asked for 29 days of weight measurement. The last measurement would be on the morning of the 29th day, giving us 28 days of complete data.

But we fucked up on the data recording sheet and made it seem like people should record only up to day 28. Most people followed instructions — they gave us 28 days of data, then stopped. This is our fault, we messed up.

whoops

To keep things standard, we used each person’s data at day 28 as their final day of data. For people who went past 28 days (a number of people kept collecting their data and/or kept going with the diet), we treated them as if they did 28 days exactly. We used their weight on day 28 as their final weight, counted their number of cheat days up to day 28, etc. 

At some point it might be interesting to go back and look at the data of people who did 29+ days, but again, not a project for today.

This is technically 27 full days of potato diet, since the measurement for day 28 is the MORNING of day 28. But tiny differences like this are like, eh, who cares. If the effect is substantial at all, it won’t matter anyways. Anyways, henceforth this span will be referred to as “four weeks”.

One participant (40207077) didn’t report his weight for day 28, so we used his day 29 data. Coincidentally this is also the person who lost the least weight over the 4 weeks. If you kicked him out because he often forgot to report his weight, average weight lost on the diet would be even greater.

Anyways, 64 people made it the full four weeks and completed the potato diet. Let’s review their demographics: 

  • Age ranged from 19 to 61, with a mean of 36.7 and a median of 36.5.
  • For sex, 5 reported their sex as female, 54 male, 4 other entries, and one nonresponse.
  • We estimated 6 XX and 57 XY; and we estimated 7 people with a more “female” hormonal profile and 56 people with a more “male” hormonal profile.
  • For ethnicity, 57 were white, 4 Asian, 1 Polish, 1 “several of the above”, and 1 “half-asian, half-white”.
  • Participants reported being in the following countries: 46 US, 4 Canada, 2 each in UK, Germany, and Ireland, and several singletons.

Racial diversity is definitely a major limitation of this study, especially since obesity differs a lot across ethnicities. The diet could easily work half as well, or not at all, for African-Americans. Or for all we know, it could work twice as well. The results we have so far look really promising (as you’ll see in a minute), and we think it’s important to see if they’ll generalize. So if we run another potato diet study, and you’re part of a racial group that isn’t well-represented in this study (i.e. if you are not white), your data could contribute a lot!

Retention

The first question is, what is the retention rate for the potato diet? Well, it depends how you slice it.

If you want to be maximally strict, 64 people made it four weeks out of 209 enrolled, so 30.6%.

Not too bad. This is a kind of extreme diet, and it would be pretty impressive even if only 30% of people made it to the end. Frankly, we’re impressed so many people signed up in the first place. 

But we think this is too low, in fact. Only 209 people were enrolled in the study, and because some trials were ongoing at closing, only 204 had potentially available results. 64 out of 204 would give us a retention rate of 31.4%.

But of those 204 people, 44 never entered any data. There’s a good chance most of these people never started the study, and shouldn’t be considered dropouts. In this case, retention is out of 160, and 64 out of 160 is 40.0%.

If you wanted to be maximally permissive, you could only count the dropouts who sent us an email to formally close the study. This gives us a total of 102 people, and makes the retention rate 64 out of 102 people, which is 62.7%

(Actually if you wanted to be super maximally permissive, you could only count people as dropouts if they explicitly stopped because of finding the diet difficult. Then retention would be 64 out of 91, or 70.3%.)

So we think the retention rate is somewhere between 40.0% and 62.7%, though you could make a case that the retention rate is as low as 30%. In any case, the idea that between one-third and two-thirds of people get to the end of four weeks on basically only potatoes is pretty wild.

Of course, a hard cutoff doesn’t make much sense. Most people made it some number of days between 1 and 28. Heck, five people ended the potato diet on day 27! 

When we look at the number of days people made it to, we do seem to see two (or maybe three?) clear groups: 

Clearly the most common outcome is to make it the full four weeks. The next most common is to drop out in the first week or so. 

But there’s another bump near the end of the third week, and that seems kind of interesting, especially because some people mentioned hitting a wall at around three weeks. For example, participant 23300304 stopped on day 22 and reported: 

Initially I found the diet extremely easy… However, quite suddenly after about three weeks I started feeling unwell, with low level nausea, headaches and general tiredness. Initially I thought I was falling ill. But I didn’t really show any specific symptoms of illness. After a few days I was feeling so bad I decided to end the diet. I felt better by the end of the first day eating my usual diet again.

Similarly, things were going great for participant 63746180. They had already lost about 10 pounds over 18 days and seemed to be enjoying it. But then:

My reason for ending is that I was hungry to the point of headache and dizziness, but could not force myself to eat a potato.  It was a weird experience, my body was screaming for food but I couldn’t swallow a potato.  I went from pretty happy with eating potatoes to completely unwilling to eat a potato in the span of a day. 

So there might be something interesting with people hitting a wall at three weeks or so. However, as you can see from the histogram, it was a minority of participants.

4. Weight Loss

Of the participants who made it four weeks, one lost 0 lbs (participant 40207077). Everyone else lost more than that.

The mean amount lost was 10.6 lbs, and the median was 10.0 lbs. The 99% confidence interval on the mean is 12.1 to 9.1 lbs of weight loss. The greatest amount of weight lost was 24.0 lbs, from participant 74282722.

We thought this might end up being bimodal — some people going into potato mode and other people just struggling through — but it looks pretty normally distributed around 10 lbs. There’s sort of a little spike around 15 lbs maybe.

We can also look at individual time series data:

And here’s the average over time: 

We can also do these plots as percent weight change, but you’re gonna be pretty disappointed, they look almost exactly the same: 

Actually Why Not Just Look at All The Data

Like we mentioned above, a hard cutoff doesn’t make much sense. Let’s just look at all the data.

Here’s weight change by total number of days completed on the potato diet for all participants who entered data: 

Seems like a clear trend. And it makes sense to us; if you make it 22 days on the diet, you get about 3/4 the benefit of making it the full four weeks on the diet.

We can see that only two people reported a net weight gain on their diet, and of only 2.3 and 0.1 lbs. In addition, twelve people did report exactly no weight change — though nine of them only entered data for day 1, so they couldn’t have lost any weight. It doesn’t look like the potato diet can go “wrong” and you can gain a lot of weight. 

We want to point out that the person who lost the MOST weight (24.8 lbs; participant 71319394) actually ended the diet on day 27 — “I am calling it done a day early, but I think it has gone really well for me and was really easy for about 3 weeks.” — so he doesn’t appear in the “completed four weeks” analyses.

Also note the outlier, participant 89861395, who reported losing 41.6 lbs in 18 days. We assume this is an error, in part because he reported being 296.8 lbs on day 17, and then being 267.0 lbs on day 18, after which point he recorded no further data. It seems unlikely that he lost 29.8 overnight just before closing the study. Probably he lost 11.8 lbs total before stopping, the number suggested by his weigh-in on day 17. 

When we plot this over time, it becomes clear that it didn’t really matter if people “finished” or not:

People lost about a half a pound a day on average, though with quite a bit of variation (we did kick out that one measurement claiming to lose 29.8 lbs in a single day, since it’s probably a typo). There appears to be no meaningful difference in the daily weight loss of people who did and didn’t make it the full four weeks. In fact, people who made it the full four weeks had slightly lower average weight loss, a mean of 0.41 lbs a day compared to a mean of 0.55 lbs a day in people who didn’t make it four weeks.

Here’s how the potato diet COULD have worked: some people don’t lose weight, so they quit, and other people do lose weight, so they keep going. If that happened, we would see a really successful group of people who made it to four weeks and lost a bunch of weight, and another group of dropouts who lost little or no weight. But that’s not what happened. Almost everybody who tried the diet seemed to lose about the same amount of weight per day. So something causes the dropouts to drop out, but it’s not that the diet doesn’t work for them. The diet works for pretty much everyone, at least for however long they can stick to it. But then, for unclear reasons, some people hit a wall.

You might want to know, how much weight will I lose if I don’t make it four weeks? How much weight will I lose if I start and keep going until I hit a wall? Well, it depends on how long it takes for you to hit that wall, but we can talk about what you can expect on average.

People who entered at least two weight measurements but didn’t make it four weeks lost an average of 5.5 lbs, with a median of 4.2 lbs and a maximum weight loss of 24.8 lbs.

If we pool everyone who entered at least two weight measurements, they lost an average of 7.7 lbs, with a median of 6.9 lbs and a maximum weight loss of 24.8 lbs.

So strictly speaking, if you start the diet, based on these data you should expect to lose 7.7 lbs on average. If you fully expect to make it four weeks for some reason, then you should expect to lose 10.6 lbs; and if you for some reason are sure you will NOT make it four weeks, you should still expect to lose 5.5 lbs on average.

Finally, it’s worth noting the subjective element. Just look at how happy many participants were with the diet:

I lost almost 25 lbs and have felt great throughout. I have been sleeping fine and having plenty of energy. 

Well I thought that was super fun and I’m happy to have done it. Lost about 16 pounds. … Anyway, I had a blast. I would consider doing potatoes again in the future. This is probably the thinnest I’ve been in at least 15 years or so.

Thank you for doing this. I’ve found it very valuable and think potatoes will continue to play a role in my health.

Thanks for organizing this!

Thanks for the opportunity to do this, it’s been an interesting ride, and I did lose weight. 

Hi! Thanks for doing such a great study!

I felt really good during the diet. This is the best I’ve felt in several years. My clothes fit better, I’m not as tired all the time, my back and knee has felt better than they had for the last 6 months.

I did it. One month, mostly potato. And I am really happy I came across your tweet about this crazy and kinda dumb idea for a study. Over this past month I lost pretty much exactly 10 kg / 22 lbs. It felt easy most of the time, and I feel fantastic. My goal of a BMI < 30 is still 20 kg away, but that feels achievable for the first time I can remember.

Thanks for running this experiment! It was very fun, and I wish there were more things like this going on in the world. 

Thank you so much for including me in your study! It has been a huge boon to me personally and it was nice to be able to contribute to science!

I had a good time overall with the diet, and ultimately I think the viscerally-felt revelation that an adjustment to my diet gives me far greater mental clarity will be long-term life-changing. Thanks for that.

By BMI Bracket

We can also break down these same analyses by starting BMI bracket.

None of our participants were “underweight” (BMI < 18.5) to start. Of the people who entered any data, 27 had starting BMIs between 18.5 and 25, 66 were BMI 25-30, 43 were BMI 30-35, 17 were BMI 35-40, and 7 had starting BMIs above 40. 

Retention by Starting BMI

Overall, it doesn’t seem like retention is much better or worse for people with higher or lower starting BMIs. This is a little surprising — you might expect leaner people to drop out more, since they have less to lose. Or you might expect heavier people to drop out more, because they presumably have a harder time losing weight. But we don’t really see much evidence for either.

We can also plot these variables to get a better look. We’ll adapt the colors from this uh lovely diagram by the CDC:

Again, we see pretty similar retention across groups. This plot shows the days completed, out of 28, by people in each bracket. Vertical lines are medians:

People with a BMI < 25 do seem to be more likely to drop out on the first day, but that might just be noise.  

Weight Loss

And here’s weight loss for people who completed the four weeks by BMI bracket. Again, vertical lines are medians:

As expected, people with higher starting BMIs lost more weight. We can also show this as time series: 

What is not expected, and what we find quite surprising, is that people who started the study with a BMI of less than 25 (what they call “normal weight”) often lost weight as well. And not just a little weight, a decent amount of weight. Median weight loss for BMI < 25 was actually 7.3 lbs! 

This becomes more striking if we break it out as percent body weight lost: 

A really interesting example comes from Nicky Case, who shared her experience as a, uh, a case study

I was already “normal BMI”, but signed up coz fighting science’s ivory tower with potato is funny

(Also the diet may help with anxiety/depression. And it’s  good to see if there’s a “floor”, i.e., it only works for “high” BMIs but not “normal” BMI)

I started 5’8″, 137lb. Already middle-low range of “normal BMI”.

I’m now on Day 19 of “try to eat only potato, but as much as you want” – and I’ve cheated on 8/19 (40%!) of the days – I’m *still* losing roughly 2.2lb/1kg a week(?!) 

(& from SMTM’s early data, “losing roughly 2.2lb/1kg a week” seems to be common for the volunteers so far: https://mobile.twitter.com/mold_time/status/1530527527680327680… )

(It *is* really weird, tho, that I’m getting about the same effect size even when I already started “normal” BMI *and am cheating a lot*)

All of Nicky’s feedback is great, see it in the thread.

Nicky isn’t the only example of someone who started with a low BMI and saw it go even lower. There’s also participant 89852176, who made it the full four weeks: 

I went into it not feeling like I had a lot of weight to lose (starting weight/BMI 143/21.1), but my wife and I started together at the same time, and she had more to lose. In addition, I was hoping for an improvement in my blood pressure (typically 120ish/85ish); I haven’t seen a significant change there. However, I did see significant weight loss; my ending weight/BMI (this morning, day 29) was 132.4/19.5.

Naturally we are wondering why people who are already at the bottom end of the range for “normal weight” are losing weight on this diet. Two possibilities come to mind.

One possibility is that the natural human BMI is really around 19. These days we think of 22 or 23 as pretty normal, but that seems to be the high end for hunter-gatherers. 

For example, this review says:

Walker and colleagues compiled body size and life history data for more than 20 small-scales societies. They report mean ± SD body mass indices (BMI) of 21.7 ± 2.9 for n = 21 adult female cohorts and 22.2 ± 2.7 for n = 20 male cohorts, mid-range within the WHO category for ‘normal weight’ (BMI: 18.5–24.9; WHO). … within the Hadza hunter-gatherer population, we find little evidence of overweight or obesity. BMI for both men (20.0 ± 1.7, n = 84) and women (20.3 ± 2.4, n = 108) 20 to 81 years remains essentially constant throughout adulthood and similar between sexes (Fig. 1). 

And Staffan Lindeberg, in his book Food and Western Disease, says: 

The average BMI at 40 years of age [for hunter-gatherers] has typically been around 20 kg/m2 for men and 19 kg/m2 for women. After the age of 40, the BMI for both sexes drops because muscle mass and water content decrease with age and because fat is not increasingly accumulated.

So if the potato diet is resetting your lipostat (if you’re not familiar, we describe this below) and sending your BMI towards what it would have been if you hadn’t been raised in a modern environment, maybe your BMI is headed towards the hunter-gatherer range of 19-20. 

It doesn’t seem like potatoes would send your BMI any lower, in part because there have been cultures that lived almost entirely on potatoes and they did not all drop to BMI 10 and die. For example, take this account of the Irish, from Adam Smith of all people (h/t Dwarkesh Patel):

Experience would seem to shew, that the food of the common people in Scotland is not so suitable to the human constitution as that of their neighbours of the same rank in England. But it seems to be otherwise with potatoes. The chairmen, porters, and coal-heavers in London, and those unfortunate women who live by prostitution, the strongest men and the most beautiful women perhaps in the British dominions, are said to be, the greater part of them, from the lowest rank of people in Ireland, who are generally fed with this root. No food can afford a more decisive proof of its nourishing quality, or of its being peculiarly suitable to the health of the human constitution.

Another option is that potatoes just have super weight loss properties that work no matter how much you weigh (but more on this later).

Adherence

We say “nothing but potatoes”, but the potato diet is actually a lot more permissive than all that. You get oil, spices, and drinks, and in our version of the diet, we said, “Perfect adherence isn’t necessary. If you can’t get potatoes, eat something else rather than go hungry, and pick up the potatoes again when you can.” 

People took us at our word, and many people chose to take several cheat meals or cheat days (several people mentioned loving this aspect of the diet). For each day, they reported whether or not they broke the diet, so we have an estimate of how many cheat days each person had, and we can look at that as part of this analysis.

We do want to remind you that this is self-report. Different people had different standards about what counted as breaking the diet, and some people were more rigorous about tracking this variable than others. It might be a good future project to go through all the raw data at some point and get better estimates for adherence based on the comments.

But that said, let’s take a look at them cheat days:

Only five people reported not a single cheat day. Everyone else said they broke the diet at least once. Most people cheated a few times, but a few people (36%) broke the diet for more than a week’s worth of days.

This is important because clearly the potato diet’s effects are robust to a couple’a cheat days.

We can take a better look at this with a nice scatterplot. Here we compare number of cheat days on the x-axis to weight change on the y-axis: 

You can see there’s a bit of a trend between more cheat days and less weight loss. Remember, higher numbers here are less weight loss; zero lbs is at the top. People on the left, who cheated very little, lost a whole range of weights. People on the right, who took more than 14 cheat days, tended to see much less weight loss. 

The basic correlation is only r = 0.176, and not significant. Though we do notice a weird outlier in the bottom right, and without that participant, the correlation is r = 0.303, p = .014.

One interesting thing here is that the five people who reported 0 cheat days are all tightly clustered around losing 10 lbs, so the diet does seem to maybe be the most reliable for people who don’t take cheat days. But some people who took cheat days lost a lot more than that. 

So overall we see that cheat days maybe matter a bit, but not a ton. It’s looking good for the 90% potato diet.

Heck, it’s looking good for the *40%* potato diet! Participant 68030741 broke the diet on 27 out of 28 days. (And actually didn’t mark down if he broke the diet on day 22, so maybe 28 out of 28.) He says:

I couldn’t get enough protein with only potatoes, so I supplemented with other food. Also, eating only potatoes without anything to accompany them quickly became too monotonous for me. So, I ended up getting only 40% of my calories from potatoes, but I still lost 7 lb over 4 weeks. I limited my intake of non-potatoes, but I ate potatoes ad libitum. I didn’t try to limit my daily calories; in fact the opposite, I often just wasn’t hungry enough to eat more.

There are some similar stories from other people, like participant 48507645:

I was really surprised at the results. While I cheated way more often than I wanted or anticipated, I still lost almost 10lbs. That’s with cheating almost every weekend (due to unforeseen social obligations). 

And here’s one from participant 35182564:

I also must confess, that I was not very strict with the “no dairy” rule. I took milk for my coffee (4-5 cups a day) and occasionally a small piece of butter or some spoon of plain yogurt to go with the cooked potatoes. This does not seem to have impacted the successful outcome. But it made the diet so much easier and also improved the “empty stomach” and “hungry” feelings a lot. Everything besides these “tiny” amount of dairy, I noted in the sheet.

The most extreme case study may come from Joey “No Floors” Freshwater, who shared his story on twitter. He wasn’t able to enroll in the study proper but he decided to do his own version consisting of “1-1.5lbs of potatoes a day when I could”, or about a 20% potato diet. Turns out it works just fine, for him at least. Here are some screenshots:  

So it looks like the 20% potato diet can work, at for least some people.

EASY POTATESY

Most people who made it the four weeks report the diet being anywhere between “pretty easy” and “real easy”.

(24235303) It was remarkably easy to stick to the diet.  I generally wasn’t hungry and when I was I just ate a potato.  I only had cravings for other things when I was directly looking at them, such as when I was helping to put away groceries for my family.  This seemed to require a lot less willpower than my previous successful diets.

(41297226) I lost 17 lbs in 28 days, felt very few food cravings or aversive hunger, didn’t get tired of potatoes.

(14122662) I felt mostly normal during this diet. I did often miss going out to restaurants or just having a non-potato meal, but the craving was never so strong as to be unbearable.

(63746180) Most of the time I had a good experience on the diet.  I didn’t feel cravings for other food.  Sometimes I would imagine eating out at a restaurant as a fun thing to do, but it didn’t have the same urgency as typical food cravings.  

(57747642) General Diet Thoughts: It’s really surprisingly easy. I was skeptical that I’d be able to finish the four weeks when I started, but once you get in the groove (and learn some tricks for prepping large quantities of potatoes quickly and easily) it’s extremely simple to stick with it. I basically never felt hungry or low energy.

Even some people who dropped out mentioned that it wasn’t hard for them. For example, take this report from participant 70325385: 

Overall, it was a good experience. I thought getting fewer calories would have a more detrimental effect on my mood and energy, to the point where I wouldn’t be able to function normally at all. What I noticed was mostly a ~2 point penalty to my mood and energy, which isn’t that big in the grand scheme of things but enough to be an annoyance.

On the other hand, we want to note that the potato diet was really, really hard for some people. Here are a few stories from people who stopped before completing four weeks.

(52058043) Not only is it very inconvenient to daily life and travel, it also feels pretty gross.  I feel uncomfortably full, but still wanting anything, anything at all, that isn’t potatoes.

(86547222) In short, my experience was not great. First two days I didn’t peel potatoes and my digestion went crazy. After that I started to peel potatoes, which helped but not by a lot. During those 9 days that I stuck to the diet I mostly felt apathy. The diet removed any joy associated with food from my life, and I missed that.

More speculation on some people loving it and other people hating it later.

Beyond the self-report, we can also look at people’s daily ratings of how easy they found the diet, on a 1-7 scale from 1 “hard to eat only potatoes” to 7 “lol this is so easy, I love potato”.

We averaged each person’s ease ratings over the four weeks for a mean ease rating. The mean of these ratings was 4.6 and the median was median 4.7, both of course on a 7-point scale.

It does seem like people who found the diet easier lost a bit more weight:

The correlation here is small, only r = -0.155, and not significant. This may, however, be the result of one participant who lost almost 25 lbs but seems to have hated every day of it. See him in the far bottom left? Without that guy, the correlation is r = -0.326, p = .008.

This is participant 74282722, who is also the outlier on the previous plot, with 23 cheat days out of 28 days of the diet. Perhaps this guy’s experience was not typical.

Comparison to other Diet Studies

It’s not a contest, but we think the potato diet compares pretty favorably to the rest of the literature.

Meta-analyses like this one do find that many diets cause 10-20 lbs of weight loss on average. But these studies tend to run for much longer than the study we’re reporting on today. The studies in that meta-analysis ran for 16-52 weeks (median 24 weeks) to get that 10-20 lbs of weight loss. If the potato diet went for 16-52 weeks… well that would be something wouldn’t it. At an average weight loss rate of half a pound a day, you do the math.

This meta-analysis compared interventions based on diet, exercise, and diet plus exercise found that people lost about 23.5 lbs on just a diet, 6.4 lbs on an exercise regime, and 24.2 lbs with diet plus exercise. Again this is pretty good, but these diets were all run for what they describe as “short durations”, which is 15.6 +/- 0.6 weeks.

This two-year trial from The New England Journal of Medicine compared low-fat, Mediterranean, and low-carbohydrate diets in a randomized design. All three of these diets saw only about 2 kg (4.4 lbs) weight loss at one month. This is less than the potato diet participants who dropped out before reaching four weeks, who lost an average of 5.5 lbs (median 4.2 lbs).

Maximum weight loss on these diets was at around 5 months in, when participants had lost an average of about 5 kg (11.0 lbs) in the low-fat and Mediterranean diets, and an average of about 6.5 kg (14.3 lbs) in the low-carb diet. This is about comparable to the weight loss on the potato diet, but it took five times as long.

The attrition rate for the potato diet is pretty comparable to other diet studies. That NEJM paper mentions that “common limitations of dietary trials include high attrition rates (15 to 50% within a year)”, and as a sampling from some papers we grabbed at random from Google Scholar, we see attrition rates of 49.3% in this study, 32.3% in this study, and 56.3% in this study.

Admittedly these attrition rates are over very different time scales, so it may be the case that the potato diet is a little harder to stick to than these other diets. But that seems pretty well offset by the much faster and more reliable weight loss.

We also didn’t include any of the intense measures many diet studies implement to keep their participants in line. We didn’t lock people in a metabolic ward. We didn’t control how they prepared their meals. We didn’t do portion estimation. Heck, most of our participants didn’t even stick that closely to the diet. Most of them took several cheat days! 

They still lost an average of 10.6 lbs over four weeks. Of those who made it the full four weeks, one lost zero pounds — the other 63 all lost at least 3 lbs. Of the participants who entered at least two days of weight data, two gained weight, three saw no weight change, and the other 146 lost weight. If you’re statistically inclined, the effect size for those who made it four weeks is d = 2.28. The potato diet is remarkably consistent.

​​It’s hard to estimate how much some of these other diet studies cost, but we’d guess at least tens of thousands of dollars. In comparison, our budget was $0. And we did the whole study in what, 10 weeks?

5. Effects other than Weight Loss

Ok, enough about weight loss. We were promised MORE.

The case studies did all mention weight loss, but they also mentioned other beneficial effects, the kind of thing we would love to see.

Chris Voigt reported major improvements in his bloodwork: “My cholesterol went down 67 points, my blood sugar came down and all the other blood chemistry — the iron, the calcium, the protein — all of those either stayed the same or got better.”

Andrew Taylor said, “I’m sleeping better, I no longer have joint pain from old football injuries, I’m full of energy, I have better mental clarity and focus.” 

This is pretty exciting, so we wanted to look for other effects beyond weight. To keep things simple, we just asked people to track their mood and energy every day, both on a 1-7 scale (7 is better mood and more energy).

We took a look at both variables, and there does seem to be something there. There’s a small trend for mood, from an average of 4.3 on day 1 to an average of 4.7: 

Of the people who made it four weeks, 45.3% reported a higher mood on day 28 than on day 1. An additional 34.0% reported the same mood (on a 7-point scale) on day 1 and day 28. 

And slightly more for energy, from an average of 4.1 on day 1 to an average of 4.7 on day 28:

Of the people who made it four weeks, 50.9% reported higher energy on day 28 than on day 1. An additional 37.7% reported the same level of energy (on a 7-point scale) on day 1 and day 28. 

But there’s definitely some variation — some people reported feeling VERY energetic: 

There were also some reports of more specific forms of feeling energetic, like increased fidgeting: 

(81125989) I also noticed I’m fidgeting a lot, but not sure if I was always fidget-y before, and I’m only noticing now since I’ve read about lipostats & Non-Exercise Activity Thermogenesis

(88218660) Definitely had increased fidgeting at various points.

We also did this extremely scientific poll on twitter: 

So it does look like a substantial minority experienced this, but still, a minority. 

Effects and Variables we Didn’t Ask for

We asked people to track mood and energy; but, perhaps foolishly, we didn’t ask them to track things like blood pressure and sleep. 

But despite our failure, many people chose to track additional variables anyways, and reported all kinds of other effects of the potato diet above and beyond weight loss.

Certainly many people did NOT experience these side effects. Many people just didn’t mention whether or not they experienced them, but for most of these effects, there were some people who specifically said they didn’t feel it. For example, participant 81125989, who didn’t feel anything: 

I didn’t feel any noticeably better or worse. My sleep, anxiety, & ability to focus were trash the last few weeks, but they’ve already been that way for months before anyway.

But it’s hard to tell for most of these effects, since we didn’t track them systematically. A project for next time (or for one of you!).

Anyways, here is a selection of effects other than weight loss that were mentioned at least a couple times, and/or that we found interesting.

Digestion both Good and Bad

Lots of people reported digestive changes. Some of these were good. Others were very bad.

(72706884) Other: Improved digestion. 

(89852176) almost exclusively loose stools alternating with mild constipation from day 12ish onward

(38751343) My only note is that when I ate potatoes for more than 24 hours, I had the best poops. Total no-wipers. 10/10 poops. I have IBS so it’s rare for me to have a solid bowel movement. Next time I decide to have anal sex, I’m definitely going to eat potatoes for 24 hours prior.

Before you go rushing to cram potatoes before your next bout of anal sex, beware: the potato diet gave other people diarrhea:

(68545713) I had trouble getting started with the diet because at first. I was leaving the skins on, and not using any salt or oil. I had quite extreme diarrhea in the beginning, which I attribute to the unusually high fiber. I also just don’t like potatoes, so not using any salt or oil made the actual eating of the potatoes very unpleasant for me.

After only a few days, I allowed myself salt and oil, and at about the same time I started “imperfectly peeling” the potatoes to reduce (but not eliminate) the fiber. This made the diet much easier for me.

Sleep

Several people reported better sleep, and sometimes reported sleeping more.

(72706884) Improved sleep, even with caffeine pills. I never woke up in the middle of the night, which is atypical.

(34196505) I sort of feel like I slept better. This is not consistent with how I usually feel on a calorie deficit–normally, I have a hard time sleeping.

(31664368) Good energy and sleep from a crappy baseline (~4 month old at home, just starting to get “normal” sleep)

(63173784) I needed more than usual sleep on the diet, but once I added chicken I was able to sleep more deeply

My sleep apnea symptoms disappeared, except when I had the one “normal” meal in the middle. I must be reacting to other foods. 

There may be a relationship between the amount of sleep people require on this diet and how much weight they lose — someone should look into this at some point.

Blood Pressure

Several people tracked their blood pressure, and they tended to see improvement, sometimes a lot of improvement. 

If you don’t look at BP measurements very often, here’s a quick refresher on what the different ranges mean, from the FDA:

Normal pressure is 120/80 or lower. Your blood pressure is considered high (stage 1) if it reads 130/80. Stage 2 high blood pressure is 140/90 or higher. If you get a blood pressure reading of 180/110 or higher more than once, seek medical treatment right away. A reading this high is considered “hypertensive crisis.”

Two people saw minor increases. Participant 76703005’s blood pressure went from 123/69 (day 1) to 138/82 (day 29). Similarly, participant 26650045 went from 115/76 (day 1) to 116/80 (day 24, their last day).  

But other people saw their blood pressure decline, sometimes by a lot.

(90638348) Blood pressure down, resting pulse down, pulse/ox up (data in spreadsheet) 

Looking at the spreadsheet, participant 90638348 saw their blood pressure go from 139/98 on day 3 (the first they recorded) to 122/88 on day 29. They actually have BP data up to day 32, when BP was 125/87

Participant 14558563 also tracked their blood pressure, and found it went from 164/100 (day 5) to 153/98 (day 29). They even have data up to day 35, when it was 150/102.

(68482929) I ate a LOT of seasoning and salt, but my blood pressure dropped to 111/73 (before the diet it was 139/something)

(57747642) My blood pressure went down from a pre-diet average of about 135/85 to an average now of about 128/70. So that’s interesting.

(57875769) I also checked my blood pressure a few times, although I wasn’t scientific about it so I’d consider this anecdotal, but on day two of my diet my blood pressure was 149/96 (yikes!) and my last reading on day 27 was 126/81. 

(66959098) I also took a blood pressure measurement before and after the diet, starting at 177/107 and going down to 130/80.

Not asking for blood pressure measurements was an oversight on our part, since the measurement is so standard and it’s so easy to track at home. If we run any future studies, we plan to include it; and if you try the potato diet on your own, we recommend that you track it! 

Pulse / RHR  

A few people measured their resting heart rate, and found that it dropped during their time on the potato diet.

Participant 90638348 reported their pulse (BPM) dropped from 78 (day 1) to 64 (day 29). 

Participant 14558563 reported their pulse dropped from 68 (day 5) to 56 (day 29). 

And participant 05999987 had this to say:

I noticed I often had to pee during the night, which is unusual for me. (Note that my version of potato diet was also very low sodium, mostly because bland potato was just fine with me and I figured if I got way out of Na/K balance my body would let me know, like a deer in search of a salt lick). More interesting is my resting heart rate went down by almost 10 bpm from ~63 to 54. 

Cholesterol

A few people got more comprehensive blood work done, and the changes they saw over the course of the diet were generally positive. 

Participant 95730133 had this to say in his closing remarks: 

As promised, here’s the results of my blood work! Taken on the first day (5/31) and last day (6/27) of my potato diet. Note the second test was also fasted though it isn’t marked.

Summary:

Total cholesterol dropped from a high 242 mg/dL to a healthy 183 mg/dL.

LDL cholesterol improved from a high 148 mg/dL to a still high 124 mg/dL (0-99 is the target range).

All other levels remained healthy and in the target ranges.

Another participant (23300304) sent us his full blood test results. Like the guy above, 23300304 saw his total cholesterol drop, from 4.5 mmol/L to 3.1 mmol/L (about 174 mg/dL to 120 mg/L in the other units). He also saw his LDL cholesterol drop from 3.0 mmol/L to 1.4 mmol/L (116 mg/L to 54 mg/L). However, his triglycerides went up, from 0.65 mmol/L to 1.79 mmol/L.

Hypomania

When we tried this diet, we experienced some pretty hardcore hypomania:

This makes sense for us because we are mad scientists. But would “normal” people experience the super-wiring effects of potatoes too? Apparently yes, though certainly not everyone.

Participant 68545713 reported:

Energetically and mentally, I felt very energetic on the diet in a “hectic” kind of way. Not bad at all for me, that’s my preferred state. I tend to think of my mental clarity as being about a) how many trains of thought I can have going at once and b) how often I lose a train of thought to a blank mind. On potatoes, I had all ~3 trains running, and I rarely lost a thought. (That is quite unusual for me, and strikes me as very unlikely to be a coincidence.) … I’d classify the energy I get from a potatoes-only diet as “frantic”, or “hectic”, or “excited”.

Participant 15106191 gave these notes:

(Day 5) Energy boost kicked in today. Feel half my age

(Day 6) Potato energy going strong. Feel like Irish Superman

(Day 15) Almost too much energy, hard to sit down at a computer and work, took a break to play basketball 

And participant 02142044 described: 

[At] one point, I was feeling a mild euphoria, and then it just stopped … I felt a sort of euphoria/hypomania that lasted from day 17 to day 20, and I’m unsure how to reproduce it

Certainly not everyone saw this effect of the potatoes. Participant 90638348 said:

Never saw the manic energy described by other folks. I was sorta looking forward to that.

Migraines 

Only one person mentioned their migraines, but most participants probably don’t have migraines to begin with, so we found this interesting. This was participant 35182564, who said:

My frequent migraines improved during the diet. I could also go much longer without food than before and the blood sugar ups and downs were less pronounced, which is probably why the migraine is better. I am very happy about that.

Acne

Similarly, one person mentioned a serious improvement in their skin. Participant 36634531: 

One unexpected consequence is that my skin is way clearer.  I usually have a lot of redness in my face and am acne-prone.  My skin has been way less red and acne has been infrequent which makes me wonder if I have a food allergy.  If relevant for genetic reasons:  I am of Jewish and English/Irish descent.

Libido

Two people mentioned libido issues; participant 95730133:

My libido was down a good bit this month, which I’ve seen during weight loss periods before.

…and participant 70325385

The diet had a fairly large effect on my energy and mood most days, and greatly decreased libido starting almost immediately.

Most people didn’t report this effect; but also no one mentioned the potato diet making them extra horny. 

Fear and Grief???

One of the strangest effects that some people reported was an increase in intense feelings of fear and grief. For example, participant 95730133, who said:

I had 2-3 days with bad anxiety, which is super uncommon for me and represents a big chunk of the days I’ve ever felt anxious. May have had something to do with the rapid weight loss / potatoes.

We also saw some clear anecdotes about this on twitter: 

Chairman Birb Bernanke also discussed this a bit more in a retrospective post on her substack:

Like I said above, potato diet is fucking weird. I mention this and the above because towards the end of the third week, I found myself crying every day. I was having actual meltdowns… five days in a row. 

I am not talking “oh I am so sad, let a single tear roll down my cheek while I stare out of a window on a rainy day” levels of gloom and general depression. I am talking “at one point I couldn’t fold some of my laundry in a way that was acceptable to me, and this made me think I should kill myself, so I started crying”. 

Is this a really dark to drop in the middle of a sort of lighthearted post about potato diet? Yes. I am sorry if you are uncomfortable reading it. Personally, I think I have a responsibility to talk about it, because the mentally weird aspect of this diet cannot be stressed enough.

If you experience this kind of side effect, we recommend you dial back or discontinue the diet. As Birb put it:

To anyone who wants to do this diet, or is considering it after the benefits I described above: I encourage you to do it, but please be extra cautious that your mental state might be altered and that you are not necessarily in your right mind.

Muscle / Exercise

Finally, let’s talk about the topic on everyone’s mind: getting swole, and staying that way.

When we opened signups, many people asked if you’d be able to get enough protein on an all-potato diet. Potatoes do have some protein, and more than their reputation would lead you to believe (3-5 g in a medium potato), but it’s true that 20 potatoes a day won’t give you as much protein as many people think you need. 

This is where we reveal that this community trial is not actually the first-ever study of an all-potato diet. There are a few very small, very old studies, and they’re pretty illuminating on the subject of potato fitness. Stephan Guyenet explains:

Starting nearly a century ago, a few researchers decided to feed volunteers potato-only diets to achieve various research objectives. The first such experiment was carried out by a Dr. M. Hindhede and published in 1913 (described in 15). Hindhede’s goal was to explore the lower limit of the human protein requirement and the biological quality of potato protein. He fed three healthy adult men almost nothing but potatoes and margarine for 309 days (margarine was not made from hydrogenated seed oils at the time), all while making them do progressively more demanding physical labor. They apparently remained in good physical condition. Here’s a description of one of his volunteers, a Mr. Madsen, from another book (described in 16; thanks to Matt Metzgar):

“In order to test whether it was possible to perform heavy work on a strict potato diet, Mr. Madsen took a place as a farm laborer… His physical condition was excellent. In his book, Dr. Hindhede shows a photograph of Mr. Madsen taken on December 21st, 1912, after he had lived for almost a year entirely on potatoes. This photograph shows a strong, solid, athletic-looking figure, all of whose muscles are well-developed, and without excess fat. …Hindhede had him examined by five physicians, including a diagnostician, a specialist in gastric and intestinal diseases, an X-ray specialist, and a blood specialist. They all pronounced him to be in a state of perfect health.”

Dr. Hindhede discovered that potato protein is high quality, providing all essential amino acids and high digestibility. Potato protein alone is sufficient to sustain an athletic man (although that doesn’t make it optimal). A subsequent potato feeding study published in 1927 confirmed this finding (17). Two volunteers, a man and a woman, ate almost nothing but potatoes with a bit of lard and butter for 5.5 months. The man was an athlete but the woman was sedentary. Body weight and nitrogen balance (reflecting protein gain/loss from the body) remained constant throughout the experiment, indicating that their muscles were not atrophying at any appreciable rate, and they were probably not putting on fat. The investigators remarked:

“The digestion was excellent throughout the experiment and both subjects felt very well. They did not tire of the uniform potato diet and there was no craving for change.”

So previous all-potato diets didn’t lead to serious atrophy; it seems like people can maintain muscle just fine on a potato diet, and maybe even build muscle. Despite being relatively low in protein, that protein may be exceptionally available or otherwise of unusually high quality.

Empirically, participants in our potato study seemed to lose mostly fat, not muscle. Participant 10157137 used a Fitbit Aria scale to measure fat %, which went from 17.3% (day 1) to 16.5% (day 28). And they were not alone: 

(57875769) I lost nearly 17 pounds, and if the body composition on my scale is to be believed, roughly 75% of that was fat. 

(46804417) In total I lost 12.5lb (5.7kg) and 4.3% (33%->28.7%) body fat. I measured the fat % using a FitBit Aria 2 scale. I found it impressive that almost all the weight I lost was fat, usually when I diet I lose some fat but close to maybe half of the total?

Maybe you don’t trust these home scales, and you know what, fair enough. But these numbers are backed up with athletic performance, which indicates no noticeable muscle loss: 

(41297226) Weightlifting: I’ve been lifting off an on the last couple months. Went from deadlift/squat/bench of 155/165/135 on April 29th (day -5 pre-diet) to 160/145/125 on May 16th (day 13, first time lifting during diet) to 175/150/140 (day 21). I’d say: inconclusive, but doesn’t seem like I was held back from improvement by potatoes (+ taking 4g of BCAAs post workout)

(14122662) In general, I was shocked by the amount of weight I lost, especially since I started out slim and didn’t have much weight to lose in the first place. I had to actively make sure I was eating enough each day so that I wouldn’t lose even more weight. That said, I felt fine throughout the diet and stayed physically active by rock climbing, hiking, and playing kickball and tennis. My health was never a big concern for me.

(01772895) I went on several pretty intense road/mountain bike rides and kept up while feeling good over the course of the diet.

(05999987) I stuck with my usual level of physical activity which is at least 5 miles of walking a day, with some plyometrics. On the few occasions I did do some more intensive activities (a hike with a long, steep uphill portion) or jogging I felt more muscularly tired than usual, though in general I had average for me, or slightly above average energy.

(74872365) I felt unable/unwilling to lift weights during it. I was lifting 3x a week beforehand, and tried near the beginning to workout a couple times but started feeling kinds of joint soreness I wasn’t used to (assuming because of impaired recovery from previous workout). I tried to give it a few more days rest and just suddenly felt very much like not exercising… so I hardly lifted at all for the rest of it. But after the diet was over (a few weeks after it, what with moving and stuff) I got back into gym, got going again at reduced weights, and in two weeks matched or exceeded previous personal bests on most lifts (but haven’t gotten back to previous bench press best). I overall feel very positive about the way in which I was able to resume working out and hitting PRs after it was over, it wasn’t an overall bad thing for my lifting in the grand scheme.

On the other hand, not everyone had sustained athletic performance on the potato diet. For example, participant 57747642 said: 

One difficulty for me was keeping up my running volume on the diet. Pre-diet I ran ~20 miles a week. During the diet I found longer runs to be extremely tiring–I think I was just in too much of a caloric deficit to have much glycogen available. I started cheating by drinking a bottle of gatorade before my longer runs and that seemed to fix the issue. But I still only averaged about 8 miles a week of running which was quite a step down.

(15106191; Day 14) Bench press went down today, likely losing muscle along with the fat, either because of the low protein of potatoes or just the calorie deficit

(34196505) I lift weights at the gym a few times a week, and even on days when I made a point of eating a ton, I felt more fatigued and had a hard time lifting my goal weight. Physical activity seemed harder in general. This is consistent with how I usually feel about a calorie deficit.

If you’re training for a marathon that’s four weeks away, don’t start now. But for most of us, it’s clear that four weeks of the potato diet doesn’t cause serious atrophy or muscle loss.

6. Why do some people find the diet easy and others don’t? 

Some people find the diet comically easy, while other people hit a wall at some point and are suddenly unable to eat another potato. We’d like to know why. 

It’s worth distinguishing between two things; or that is to say, we think there are two ways to lose weight on the potato diet.

First, you can grit your teeth and force yourself to eat nothing but starchy tubers while fighting back your desire to eat literally anything else. A few people who made it the full four weeks seem to have had this experience. For example, participant 83122914:

It was an interesting experience, but it didn’t feel like any kind of magic bullet for long-term weight loss. I initially ate mostly mashed potatoes, but over time I found myself losing the desire to eat them. I craved meat, salad, etc. … I’ve had similar weight loss results in the past with a low-carb diet. 

But most people lost weight the other way: after a day or two of eating potatoes, their appetite waned, they didn’t want anything else, and they began to steadily lose weight.

This is the interesting part. To make this easier to talk about, let’s call it entering “potato mode”, or “potatosis”. Actually, Greek for potato is “patata”, should it be “patataosis”? 

Also worth noting that it’s not like the potato diet was just easy for some people and hard for others. More like, almost everyone found it easy at first. Some people found it easy for days or weeks and then suddenly hit a wall. So the question may be more like, why do some people hit a wall at three days, others at three weeks, and others apparently not at all? 

Demographics

It’s possible that the difference between the people who found the diet easy and the people who hit a wall will be something easy to notice, maybe basic demographic variables like race and sex. Let’s see:

The group of participants who provided us any data were mostly male (any way you slice it), mostly white, and mostly from the US.

But overall, basic demographics don’t seem to track onto who made it four weeks and who ended the study early. People who made it four weeks were slightly older, more likely to be from the US, and less likely to be white, but none of these differences are very big.

The only difference that jumps out is by sex. About 20% of the people who got to the point of recording data were female, compared to only about 10% of the people who made it four weeks.

We’re not sure why, or if this is even a real result. With so few female participants to start with, this could just be random noise. 

Participants who are XY did report the diet being a little easier, with a mean ease rating of 4.4/7, compared to 4.2/7 for XX participants, but this is not significant (p = 0.530). 

We also noticed that XY participants did complete slightly more days overall, but it’s not clear if this is robust. Looking at the plotted data, it doesn’t seem like a huge difference: 

It’s notable that our three big case studies (Chris Voigt, Andrew Taylor, and Penn Jilette) were all XY. We also did look at Brian & Jessica Krock, though, and Jessica Krock is XX. She made it pretty far on an all-potato diet, but she also seems to have found it much, much harder than most people do:

The first day of potatoes sucked. I seriously contemplated quitting during the FIRST day. After eating my first round of potatoes, I literally walked from our apartment to a grocery store to look at the extra cheesy hot-and-ready pizza I thought I needed. I gazed at the pizza and walked around the store looking for something to eat. Luckily, I was able to keep it together and walk out of the store and back home to my pantry full of potatoes.

I’m not trying to be dramatic, but it was seriously one of the hardest things I’ve done in my life. It took more will power than I thought either of us had.

But with such a small number of XX participants, it’s hard to be sure.

That said, 20% (6 out of 30) of XX participants made it four weeks. If the potato diet only works for one out of every five people with two X chromosomes, that’s still pretty good.

We do wonder if this is a real effect, and if so, why it happens. It would be good if future studies had more XX participants. 

Having lots of trans participants would also help us tell if the cause is more hormonal or more chromosomal. In this study, there aren’t enough people whose chromosomes and hormones don’t “match” to actually disentangle any effects.

Oil

Some people seemed to have an easier time, or see better weight loss, when they used less oil.

Not that kind

For our own part, one of us was fine for the first two weeks on a relaxed all-potato diet with olive oil, but didn’t see any weight loss until switching to a no-oil version for the last two weeks, when they lost 10 lbs. 

Participant 68482929 did some analysis of his own on this question: 

The amount of olive oil I consumed had a noticeable effect on how much weight I lost:

image.png

The main thing I craved on the diet was more olive oil. If I ate 10 tbsp / day, that felt about right (and my stool was normal and I gained a bit of weight on those days). The more I cut the oil, the more I had intestinal distress, and the more weight I lost.

Here’s that image: 

Participant 88218660 mentioned something similar: 

third week – started making air fryer fries at home with < 1 Tbsp of oil and eating pretty much only these. Also allowed myself to have ketchup – I’d estimate an upper bound of 200 calories per day of ketchup, but I expect it was less than that. Stopped losing weight. Very unclear if this is a natural plateau or an actual effect of ketchup. Cravings came back in force, as did normal hunger feeling.

Final day – switched back to mashed potatoes with no oil. Hunger was gone again, cravings were dampened, but didn’t immediately lose any more weight.

It’s not clear if this was the oil or the ketchup (or something else) but they definitely seem to have dropped out of potato mode for some reason. We reached out to participant 88218660 for clarification and he told us that he used olive oil at home. 

Despite these stories, many people used lots of oil throughout the diet and still lost weight. This suggests it’s not that all oil is bad and inhibits the potato diet. More likely, it’s that 1) some kinds of oil (e.g. olive oil vs canola oil) inhibit potato mode more than others, 2) certain batches / sources of the same oil (two different brands of canola oil or something) inhibit potato mode for some reason, 3) some people respond to oil differently because of genetics or microbiome or something, or probably 4) some combination of the above. Or it could just be noise, this isn’t strong evidence yet.

Nicky Case also recently did a regression analysis of her own data over 40 days, and found a strong effect of olive oil. But it looks like it was in the opposite direction — for her, more olive oil was associated with more weight loss. Check out the analysis in her twitter thread:

It’s sort of not surprising that all these anecdotes reference olive oil, since we recommended that people should probably use olive oil if they use oil at all. But it’s still kind of interesting. Recommending olive oil might have limited the amount of information we’ll be able to get out of these data! A few people did mention they did very well on Five Guys fries, which are fried in peanut oil… Five Guys, talk to us. 

Some people did keep detailed notes of their oil consumption, so it’s possible that a clear answer to this question is hiding somewhere in the data. But it’s also possible that we’d need to run a controlled experiment to figure it out, and we may do that at some point (unless one of you gets to it first?).

Salt / Sodium

Salt intake might also help explain why some people had trouble with this diet. 

We didn’t ask people to limit salt intake, but some people may have been keeping their intake down anyways, and that may have made the diet harder than necessary. Even if they weren’t trying to limit how much salt they ate, they may still not have been getting enough. Potatoes by themselves are a naturally low-sodium food. 

For example, consider the experience of participant 57875769:

Probably my biggest piece of advice is to use plenty of salt. Depending on the nutrition labels, potatoes have zero sodium or an extremely low amount. It seems hard to get the recommended amount of sodium (and I’ve seen some heterodox sources that say the recommendations should be even twice as high as they are) without adding salt to potatoes. A few days I felt kind of light headed or unfocused and I’d finding adding a little bit of salt to a glass of water (under the threshold where I could taste it) would often improve things pretty quickly.

Or this participant on twitter: 

Some people also mentioned craving pickled things, which could be the manifestation of a salt craving:

(01772895) Interestingly toward the end, my main cravings were actually for pickled vegetables for some reason.

Of course, we don’t know for sure if the people who dropped out early WEREN’T getting enough salt. But if some people were avoiding salt this could explain some of the difference.

Health

Another possibility is that finding the potato diet difficult can be an early sign of health issues.

Potatoes are high in potassium, and the kidneys need to do a certain amount of work to clear all that potassium from your system. They’re also high in certain toxins. A healthy body under no extra stress is equipped to handle these toxins no problem. But if your health is compromised, it might be another story. 

If you eat one potato, your body will be able to deal with the extra potassium and the low levels of plant toxins. If you eat nothing but potatoes and you have reasonably healthy kidneys, again your body will be able to handle it. But if you eat nothing but potatoes and you have poor kidney health, at some point your poor kidneys may not be able to handle all the extra potassium, potato toxins, and other junk. This will make you start to feel terrible, and may explain why some people did fine on the potato diet for a long time and then suddenly started feeling terrible.

Kidney function seems like the simplest case, but other kinds of hidden health issues could also give your body trouble.

The clearest example comes from Alex Beal (who gave us permission to use his case as an example). He was one of our earliest participants in the potato diet, and also one of the first to drop out of the study. He started tweeting about his experience, did ok on the first meal, but soon found himself feeling awful and totally unable to stand potatoes. He published a log of his experiences here, where he says: 

I’ve decided to drop out of the study after less than 48 hours. This diet kicked my ass.  

Beal stopped the diet on May 1st. A few days later, he found out he had prediabetes:

This maybe explains why he had such unusual trouble with the potato diet (remember, 90% of people who entered at least one day of data made it more than two days, and 40% made it all the way to day 28). Beal has a (mild) metabolic disorder he didn’t know about when he started, and it’s pretty reasonable to suspect that this may have limited his ability to deal with all these potatoes.

We discussed this with Beal and he agrees it’s plausible. “In a study population of obese folks,” he says, “I do worry undiagnosed diabetes or prediabetes is a risk. It’s very common for it to go undiagnosed.” This is similar to something JP Callaghan mentioned, where he said, “There are tons of people walking around with their kidneys at like 50% or worse who don’t even know it.”

Beal did mention that his kidney numbers came back ok, so it’s probably not literally potassium clearance in his case (though who knows).

One strike against this explanation is that younger people generally have better kidney function, so if this were why people are dropping out of the study, you’d expect to see many fewer dropouts among younger people, which we don’t see. But for what it’s worth, Alex Beal is pretty young and he had undiagnosed prediabetes before signing up for the study. It’s possible that we recruited a sample that has disproportionately high numbers of young people with undiagnosed renal and/or metabolic disorders.

In any case, finding the potato diet really hard may be an early warning sign for kidney issues and/or diabetes, possibly because the high levels of potassium put a strain on your kidneys that you wouldn’t normally experience, so it might reveal problems you wouldn’t normally notice. So the potato diet may be a useful at-home diagnostic tool.

If you had a hard time with the potato diet, especially if you were only able to make it a few days, talk to your doctor about checking for kidney function and prediabetes.

Whatever you find out, please let us know, that’s important data.

Peels

A related issue comes from potato peels.

A number of people mentioned that peeling the potatoes made the diet noticeably easier:

(02142044) The diet was a bit tough at the beginning, probably because I didn’t peel them. 

(68545713) After only a few days, I allowed myself salt and oil, and at about the same time I started “imperfectly peeling” the potatoes to reduce (but not eliminate) the fiber. This made the diet much easier for me.

(86547222) First two days I didn’t peel potatoes and my digestion went crazy. After that I started to peel potatoes, which helped but not by a lot.

This matches our experience. On the potato diet, there was a point at which the peels started getting disgusting — but without the peel, potatoes continued to be delicious. We were very pro-peels starting out, but by about halfway through, we started peeling them and that made a clear difference.

This is interesting because it certainly goes against common wisdom about the peels — that they’re especially nutritious, that they’re good for you, and so on. It’s true they’re high in fiber, and it may be fine if you are eating only like, four or five potatoes now and then. But as Stephan Guyenet points out:

Peel [potatoes] before eating if you rely on them as a staple food … Potato peels are nutritious but contain toxins.

Again, your body can handle most vegetable toxins in small doses. But if you are eating a lot, at some point they might get to the point where it’s a problem.

So it could certainly be that past a certain point, eating the peels will become difficult for some people. Or it could be that the peels are generally fine if you’re healthy, but they pose a problem for people with undiagnosed poor kidney function. There could easily be a peels * kidney interaction.

It could also just be fiber. Lots of people reported digestive issues, and the peels are especially high in dietary fiber. 

So it’s possible that some people who dropped out early could have made it further if they started peeling their potatoes. If you’re having trouble on the diet, we definitely recommend ditching the peels.

It’s Random

Like we mentioned, potatoes contain toxins, and some potatoes contain more toxins than others. For example, levels of the toxin solanine increase when potatoes are improperly stored, or exposed to too much sunlight, and green potatoes tend to have more solanine.

Most bags of potatoes are fine, but maybe one day you go to the grocery store and just happen to get a bag of greener-than-usual potatoes, which make you feel sick, and since you’re being careful, prompt you to end the diet early. From your perspective you can’t tell why you suddenly got sick, but from a god’s-eye-view, it was the bad batch of potatoes. So maybe random chance is what’s causing some people to hit a wall.

(Just avoiding green potatoes wouldn’t totally fix the problem, because potatoes can be high in toxins without being green. But definitely do avoid green potatoes.)

If this were the case, it would look pretty random who drops out. It does look pretty random who drops out. So maybe the dropouts are from some kind of random factor like this!

7. Why the Heck Does the Potato Diet Work

The human body has a lipostat that regulates body weight, and the lipostat has a setpoint, a weight that it wants to maintain. For the sake of an example, let’s say it wants to maintain a BMI of 23. The lipostat can detect how much fat is stored and takes action to drive body fatness to the set point of BMI = 23. If your body’s BMI is below the setpoint, the lipostat will drive you to eat more, exercise less, sleep more, and store more of what you eat as fat. If your body’s BMI is above the setpoint, the lipostat will drive you to eat less, move and fidget more, and store less of the food you eat as fat.

People become obese because something has gone wrong with the lipostat — for some reason it is defending a set point above BMI 30, and all the regulatory systems of the body are working together to push body weight to that level and keep it there (for more information, see here).

It seems clear to us that something about the potato diet lowers your lipostat set point, and weight loss kicks in because the lipostat starts to defend that new, lower weight.

When you run a normal calorie deficit (don’t eat as many calories as you need), you get sluggish, you lack energy, you get hungry, and you have a hard time exercising. This is because your body wants to defend its weight at the current set point, whatever that point is, and will work really hard to keep you from getting lighter.

But when you are heavier than your current set point, the body pulls out all the stops to help you lose weight and drop to the set point. You feel more energetic, you fidget to burn extra calories, your body temperature goes up, you stop feeling hungry, and so on. In line with this, people in potato mode reported being very energetic, having hypomania, fidgeting all the time, and having no trouble exercising. This is exactly what we’d predict if your lipostat set point suddenly went down.

In addition, there are two special points that strongly support the idea that the potato diet lowers your lipostat set point. 

First, some people keep losing weight after stopping the diet. We think this means that the lipostat set point dropped faster than weight loss was able to follow, and it took a few days after the diet was over for BMI to catch up. If the diet just worked on caloric restriction, then you would expect people to start gaining weight again after stopping. But that’s not the case, or at least, not always the case.

(36634531) My weight is still holding steady after resumption of a typical diet.  Are you guys going to ping the participants in X months to see if we return to baseline? 

(57875769) Since stopping my weight has stayed pretty flat (I was 215.3 lbs this morning and I ended the diet at 215.2, and I was traveling for a few days which usually causes me to gain weight) and I find that I have a much smaller appetite than I used to. I’m having to re-learn how much food I should serve myself or order at each meal because I’m used to eating much more. 

This is just suggestive for now, but we’ll know more in 6 months when we do the first followup. 

But the biggest sign that the potato diet lowers your lipostat set point is the overwhelmingly common experience of how the potato diet makes hunger feel entirely different.

(36634531) My appetite did eventually tank.  I was down to one meal a day.  I don’t know if I was just full all the time or if my stomach shrunk or what.  I was never feeling hungry throughout the diet.

(68545713) [I] felt less desperate than before-potatoes when I did get hungry. It was wonderful.

(29550957) Subjective feeling is definitely that I could get hungry, but it was not an urgent problem. Completely different from my usual modus operandi of gravitating in the direction of food whenever slightly hungry.

(10010108) I simply was not hungry in the mornings. Once I did start eating, I was starving every 1-2 hours. Out of habit, I do not eat after 8 pm. Sometimes we would have dinner at 7 due to scheduling, and I would be stomach growling hungry at bedtime, between 10-12. I was not going to get up and eat, so I drank water and slept. The hunger just wasn’t there in the mornings though. 

(81125989) My sense of hunger was anomalous: some days I’d eat less than 1000 calories and feel totally fine, some days I’d get a sudden sharp pang of hunger right after a hefty meal. And on my cheat days, even when I ate to satiety, I ate a lot less than I did pre-potato diet.

(74872365) I recall feeling like hunger exists in two distinct modes, and potato diet worked helped switch one off while downregulating the other: there’s the “need to feel full and need blood sugar” hunger and the “pleasure reward hunger.” It was like when I finished a mashed potato dinner the first hunger was satiated fully but I still would have eaten a whole pint of ice cream for pleasure if I was allowed to. I still kind of wanted to eat for more pleasure, but the pleasure based eating was “deactivated” from controlling my decision, and the potatoes weren’t hitting that pleasure center. Hence I only ate up to the level of the first hunger metric, the more “physical” one, and that level was downregulated of course. During cheat days (which were all around dinner times I think), the moment I started eating non-potato, I got insanely outlandishly hungry and ate surprising amounts of food the rest of the evening. It was like I would eat a bunch and then suddenly feel empty an hour later.

 

(68030741) I limited my intake of non-potatoes, but I ate potatoes ad libitum.  I didn’t try to limit my daily calories; in fact the opposite, I often just wasn’t hungry enough to eat more.

(1772895) Toward the end of the diet, I found it difficult to eat enough potatoes. I’d be a bit tired and hungry, but the effort of cooking them and eating them seemed too much to bother with. This was an interesting experience, and gave me some empathy for a few of my friends who have a hard time keeping weight on, even with an unrestricted diet. When they’ve described themselves as sometimes being ‘too lazy to eat’ in the past, I basically found that unimaginable, as I don’t think I could ever be too lazy to eat cake, for example. However, if the reward I got from eating cake was similar to the reward I get from eating potatoes, I guess that’s how I’d feel.

What’s interesting though is that I wasn’t feeling tired and hungry and craving some other food — I just didn’t feel like eating. Maybe this is something to do with the stuff Pen Gillette mentioned about eating habits fading. Interestingly toward the end, my main cravings were actually for pickled vegetables for some reason.

(77742719) I did get more tired throughout, and my appetite actually continually decreased. Had to remind myself to eat quite often and actually made a schedule. On this last day, I had only one meal of potatoes, 500 kcal.

(90638348) Was not ever resentful or hungry, always felt “full”

(88218660) First week – no oil, pretty much all mashed, non-organic russets with cajun seasoning and hot sauce. Almost immediately I could tell my cravings were significantly dampened (though not gone, especially if I was looking at tasty food) and that the normal feeling of hunger was entirely gone for me – what was left was a feeling of being almost faint and feeling not great when I went too long without eating. Took a lot of adjusting to.

(57875769) I feel full sooner than I used to, and I feel like there is a much richer variety of sensations that influence whether I want to eat more food. I remember some people advocating that to maintain a healthy weight you just need to learn to listen to my body, which is sort of what this feels like. Perhaps the people giving that advice were always thin and so listening to their body was never hard. I’ve started feeling signals I don’t remember feeling before I started the diet. It’s almost as if the volume from some things (e.g. a hyper-palatable diet) drowned out and deafened me to all the signals I was supposed to listen to. Now I feel like I’m hearing these again.

(76011343) throughout I had a ton more energy, better mood, weird hunger effect that you guys have documented (didn’t feel hungry and had to force self to eat)

As you can probably tell, this experience was extremely common. But we should note that it wasn’t universal, even among people who lost a lot of weight. Participant 99479977 lost 22lbs but specifically mentioned no appetite/hunger effect: 

I’ve seen a lot of people mentioning how the diet changed their perception of hunger. For me at least that didn’t change. What I did notice though is that I become sated much quicker. Today I packed myself four medium size roasted potatoes for lunch during uni, and I felt sated after just three of them.

And see also this report from participant 34196505:

It wasn’t like some hunger switch flipped off in my brain after a day or three of nothing but baked potatoes–I still got hungry, and it felt similar to normal hunger. I saw people on twitter saying they were having a hard time reaching 1,000 calories a day. Can’t relate.

People did eat very few calories on this diet. Most people didn’t track calories very closely (another benefit of the diet — no calorie counting!) but some people chose to record how much they were eating. The people who recorded calories (self-report, so grain of salt here) generally reported eating very little.

For example, participant 68030741 kept super detailed notes on calorie consumption and should be the starting point for anyone who wants to dive deeper into this question. He reports eating as little as 756 calories in a given day, and never more than 1740. 

Participant 71309629 never reported eating more than 1556 kcal, and ate as little as 307 kcal one day.

Participant 07644625 has “been tracking [calories] for 4035 days … hard to stop now” and reported eating as little as 1172 kcal in a day — but also often ate more than 2000.

Participant 05999987 also said:

As for ease of diet, it was quite easy to feel full, without eating very many calories at all. This worried me the first week, even on days when I supplemented the potatoes with salmon I never ate even  1300 calories a day. In fact, I averaged 921 calories per day. 

This is consistent with the reduced appetite. But it is NOT an explanation any more than “the bullet” is a good explanation for “who killed the mayor?” Something about the potato diet lowered people’s lipostat set point, which reduced their appetite, which yes made them eat fewer calories, which was part of what led them to lose weight. Yes, “fewer kcal/day” is somewhere in the causal chain. No, it is not an explanation.

But we’re bored of trying to explain this one, so we’re going to let the cat do it:

Alternately, if you prefer your arguments to come from bipeds:

Theories 

We’ve previously written about how we don’t believe in definitive experiments, so we don’t think that the potato diet will be the silver bullet for or against any particular theory. In general, most theories predict the potato diet should cause weight loss, so the potato diet does not do much to distinguish between them.

But that’s ok, this study was not designed to help distinguish between different theories of the obesity epidemic — it was designed to see if the potato diet works under realistic conditions, and to get a rough sense of what percent of people it works for. Now that we have that, future studies can use the potato diet as a “model diet” to start pitting theories against one another. Won’t that be fun. 

Even so, the data from this first study does tell us a little bit about different theories. Compared to other diet studies, the potato diet has the benefit of being super controlled — it’s a clear baseline of potato, with few interfering factors. So let’s take a look.

Something special about potatoes?

One thing we need to address right off the bat is the possibility that potatoes cure obesity for some reason totally unrelated to the obesity epidemic.

For example: cocaine makes you lose weight. But the obesity epidemic didn’t happen because everyone was on cocaine for all of history, which kept them skinny, and then in the 20th century people started forgetting to take their cocaine, and we all gained 40 lbs. It’s just that cocaine has strong weight loss effects totally unrelated to whatever caused the obesity epidemic. 

Similarly, it’s possible that potatoes are just a potent weight-loss drug for reasons totally unrelated to the increase in obesity since circa 1970. There are a few things that make this seem plausible.

For starters, Staffan Lindeberg, in his book Food and Western Disease, has a whole section on how maybe humans were built to eat roots and tubers: 

Increasing evidence suggests that large starchy underground storage organs (roots, tubers, bulbs and corms), which plants form in dry climates, were staple foods 1–2 million years ago. There are at least three arguments in favour of this notion. Firstly, in contrast to most other animals including non-human primates, humans have an exceptional capacity to produce salivary amylase in order to begin hydrolysis of starch in the mouth. The underlying change in copy number of the gene coding for salivary amylase may have occurred approximately 1 million years ago. … Secondly, roots often need to be prepared under high temperature in order for its starch to be available for digestion and for its bioactive or toxic substances to be neutralised. There are many indications of Palaeolithic humans using fire for cooking, and one of the most common cooking methods for plant foods was probably the so-called earth oven, where food wrapped in large leaves is placed in a covered pit with hot stones or glowing coals. Thirdly, human tooth morphology, including incisal orientation, seems to be well designed for chewing root vegetables. … Our bipedal ancestors were apparently less efficient hunters than many carnivorous animals and less efficient fruit-foragers than the arboreal primates. In order to increase the caloric yield per workload (‘optimal foraging strategy’), root vegetables may often have been an optimal dietary choice. An illustrative example is the Machiguenga tribe of the Amazon, among whom one woman can dig up enough root vegetables in one hour to feed 25 adults for one day. The excellent health status among this and other starch-eating ethnic groups, including our own study population in Papua New Guinea (see Section 4.1), contradicts the popular notion that such foods are a cause of obesity and type 2 diabetes.

If we really are built to eat tubers above and beyond all other foods, this might explain why the potato diet lowers your lipostat set point to hunter-gatherer levels.

There’s also some evidence that potato protease inhibitor II suppresses appetite and reduces food intake, though these studies don’t seem to be especially targeted — it looks like they basically just gave people potato extract. 

We don’t think the evidence is all that strong, but it certainly seems possible that potatoes just suppress appetite and make you lose weight.

We’ll know more when we get the six-month followup results. If potatoes just suppress your appetite during the time you’re eating them, then once you stop eating them, you should gain most of the weight back. But if potatoes are doing something more profound, and resetting your lipostat or whatever (however they do that), then weight loss should be at least somewhat sustained by six months out. For what it’s worth, this is what we see in the case studies, like Penn Jillette and Andrew Taylor, who seem to have had little trouble keeping the weight off.

It’s possible of course that BOTH are true, that potatoes both suppress your appetite in the short term and somehow reset your lipostat in the long term. In fact, the combination of these effects would be a pretty good explanation for why the potato diet is so unusually powerful. But we’ll have to wait and see.

But assuming for a moment that potatoes are NOT a superpotent weight-loss drug for some reason, what would this tell us about other theories? 

Calorie-Counting, Willpower, and other Traditional Diets

No.

(34459757) Pretty easy as far as diets go, basically never felt hungry. Previously I’ve successfully lost 25 lbs via just calorie restriction (mostly by eating box mac and cheese and other prepackaged things with easy calorie counts), and potatoes were definitely easier and I lost weight at the same speed. 

(66959098) It felt pretty easy.  I have tried simple CICO diets before where I simply reduce portion sizes and maintain a calorie deficit, which were incredibly hard to follow through and caused me to think about food all of the time. This had no such effect, no strong hunger, no strong cravings. I am happy with the results from just three weeks.

(99479977) I have tried various diets before, but restricting calories while eating whatever I like left me hungry, which lead to overeating and actually gaining more weight. The potato diet kept me sated, allows for just enough variety (especially through condiments) to keep me engaged

(27316026) I started the study slightly overweight by BMI and mostly interested in helping out along with seeing how it went firsthand. I’m 35 and 5’9 and my weight has been slowly going up on average for a decade, interrupted by harsh diets every few years to try and get back down under 160. I’ve always succeeded at these diets, which normally lasted around 2 months and involved meticulous calorie counting. I hated these diets and was only able to maintain them with the knowledge that they would be over relatively soon. Comparatively the potato diet has been a joy. It only took a few days to settle into, but after working out a few dishes I enjoyed I wasn’t hungry and food cravings were largely absent.

(95730133) I was pleasantly surprised with the amount and consistency of weight loss on this. 2.5 lbs a week is pretty dramatic and this was even easier to stick to than when I’ve done calorie counting previously at a shallower slope (1.25 lbs/week).

(29550957) This is pretty much the best diet I’ve ever been on, including earlier this year when I also ate mostly potatoes- but with tons of dairy (butter, sour cream, cheese) on them. Despite literally messing up an entire week’s worth of days, I seem to be durably down about 10lbs.

(30719090) This has been quite a revelation:

I have been dieting on and off for about 10 years now. The only successful diet was 10 years ago when I got down to 75kg (165lbs). This was based on buying an expensive range of low carb meals. I was less overweight at the time and it was something of a struggle. The diet was eventually derailed by personal circumstances and I have since then gradually increased my weight reaching 200lbs and over recently.

All other diets I have tried have had a small loss initially, but the loss has never continued. The psychological difficulty of maintaining a restricted diet when the losses did not continue was always too much for me. I hate the feeling of being hungry.

The potato diet has been very different. I actually like potatoes so I have not found it difficult to eat them every day and I have found it very easy to resist the temptation of other food.

(35182564) Since I was very successful, losing more than 20 pounds in six weeks, I will probably continue some more relaxed form of the diet for a few more weeks. I have been trying to lose weight for years with absolutely no success. The potato diet did in six weeks, what I could not accomplish in many years. I hope I can keep the lower weight (will send an update in a few months).

(05999987) As a person who has slowly gained weight over the years until I hit the border BMI between overweight and obese and it has become very difficult to lose weight. I’ve often done a couple weeks of limiting to 1500 kCal/day with what a normal person would think healthy–lots of vegetables, some whole grains, some lean proteins, olive oil, legumes. Every time I’d lose a couple pounds, but not much more, and find myself to be quite hungry most of the time. The main difference with potato diet is that I only once experienced the brain-crashing feeling that I need to eat something immediately because my brain is no longer working due to the colloquial usage of “low blood sugar”. The rational part of my brain also didn’t notice any hunger and I could read about/watch people eat/think about delicious foods and not feel like I really wanted to eat them, and I’m the sort of person who thinks about cooking a lot. Plain cold potato was just fine with me, and while I looked forward to the end of the diet and eating normal food again on a theoretical level, I didn’t care about adding condiments, etc. 

(63833277) I occasionally had french fries or tater tots or even a couple of times pringles. My wife used some dairy in preparing the mashed potatoes and had ketchup on my fried potatoes, so probably technically every single day should have a “1” in the “broke diet” field. But if I’d done that I’d never have been able to stick with it as well as I did–I basically tried to bend the diet such that I could successfully stick with it but no further and call that success. I thought about retrospectively changing them all to 1s but there *were* days when I *actually* broke the looser diet I’d set for myself and I didn’t want to elide that distinction. Basically think of my diet as a slightly loose potato diet that’s like 95%-97% potatoes instead of 97%-99% as expected. Sorry for not being ideal about that, I figured that would be better than giving up after 5 days.

DESPITE THE DEVIATIONS, THE DIET WAS AN ASTOUNDING SUCCESS!

I’ve never lost weight before. My life has been a slow drumbeat of “this is my setpoint weight, I can’t lose any but I don’t gain any” punctuated by “Life event, my setpoint weight is now X lbs higher than it used to be”. I was never able to motivate myself to stick with diets because I was constantly half-assing them, thus not losing weight, thus seeing no point in sticking with a diet that wasn’t losing me weight.

I lost half a pound a day on this potato diet. I am astounded, as is everyone who knows me!

The potato diet is not a willpower diet. Some people saw huge effects even while cheating. Some people saw huge effects on this diet even when they had found other diets super hard in the past.

We understand if you don’t really get this. We didn’t get it either, despite reading about all the previous success stories, until one of us tried the potato diet for ourselves. Hunger vanishes in a really weird way that is hard to describe to anyone who hasn’t felt it directly. So listen to all our participants who are like “no it’s not calories, it’s not willpower”. Or try it for yourself, you might be surprised! 

Anyone else who complains about calorie-counting will be thrown directly into the sun.

Carbs make you fat

Some people think that carbs make you fat. But the potato diet seems like bad news for any “carbs make you fat” theory, since potatoes are starchy carbs. More complex versions might still have a leg to stand on, but obviously this finding is a problem for this kind of theory.

Seed Oils

There’s a theory that the obesity epidemic is caused by “seed oils”, an umbrella term for things like canola oil, soybean oil, corn oil, sunflower oil, and peanut oil. We’ve previously reviewed this theory, and found it unconvincing.  

We didn’t track the oil people were eating in any rigorous way, but many people had seed oils like canola and peanut oil on their potatoes. Since their diet was otherwise so limited, this seems like a problem for seed oils theory.

On the other hand, the amount of oil they were eating did seem to make a difference for some people. So maybe this is more evidence for “something that is sometimes in oil and sometimes not”. It fits pretty well with contamination theories (more in a bit), or anything else that might vary in oils, perhaps due to factors like different growing conditions.

Long-Term Theories

There are some theories that suggest that the obesity epidemic is the result of what we’ll call “long-term” factors. For example, evolutionary theories say that natural selection is, for some reason, pushing us towards greater body weights over time. Epigenetic theories suggest that things that happened to your parents or grandparents cause obesity, as the result of gene expression. 

Developmental theories say that people become more obese later in life because of something that happened to them early on in development or childhood. This recent massive review paper specifically argues “that obesity likely has origins in utero,” i.e. you get obese at 25 because of things that happened to you when you were an embryo.

But the potato diet poses a challenge for these theories. If obesity is caused by something that happened to you in utero, or by something that happened to your grandmother, then how come it can be reversed in a couple of weeks of potatoes? There may be ways to resolve this challenge, but it’s a challenge nonetheless. 

Mono Diet

Some people have told us, “oh you can eat any one thing and lose weight like this”. Penn Jillette also says this. He told “Good Morning America” in 2016:

It didn’t have to be potatoes, they aren’t magic. I picked potatoes because it’s the funniest word. I could have chosen beans or just almost anything.

We’re not so sure. In particular, why do people think that other mono diets work? We haven’t seen any. We encourage anyone to find anecdotes, studies, or better yet, run their own Onion Diet study or whatever.

The potato diet isn’t even really a mono diet. We explicitly allow for oil and seasonings, and lots of people lost weight with tons of cheat days. The mono-ness (monotony?) of the potato diet clearly is not the active ingredient. 

Potatoes are also unusual in that they are (almost) nutritionally complete. You couldn’t do the white bread diet and get far. But you could maaaaaaaybe do the whole wheat bread and oil diet, or the wheat bread and cheese diet. Also known as: the basic daily diet in Europe for centuries.

That said, we do think that studies (maybe more internet community trials) of other very simple diets would be interesting — especially since most cultures historically have had very simple diets, which shows there are many simple diets you should be able to live on indefinitely. So we’d love to see, for example, studies on diets composed exclusively of: 

  • Rice & beans
  • Rice & fish 
  • Rice & lentils
  • Buckwheat soba & edamame
  • Bread & olives / olive oil

(Someone should check that these are nutritionally complete first, though.)

This last one is already close to the Mediterranean diet, but it would be interesting to cut the Mediterranean diet down to literally just bread, olives, olive oil, wine, and cheese. Or literally to just bread and olives / olive oil, if you could survive on that. 

So anyways, if you are sure that any mono diet would work, please do run your own study, we want to see it. We’d be happy to discuss study design with you!

Food Reward

Some people put the obesity epidemic down to a factor called “food reward”. They say that people are obese now because food has gotten more delicious, and that the potato diet causes weight loss because potatoes aren’t delicious. An attempt to describe the theory might look something like this:

People are more obese because food is way more fun to eat now. You can even be agnostic about why food is more fun to eat, and maybe it’s a million small reasons. But over time food producers have figured out how to hit that mental g-spot that makes people go YUM, and when you do that, people eat more than they should and they gain weight. The potato diet works because potatoes are boring and so people don’t overeat.

To be frank, we still don’t really get this theory. That is, we don’t think it makes sense. 

First, we’re not convinced modern food is more delicious than old-timey foods. They had butter and ham and sugar and ice cream and even donuts back in 1900. Check out our review of foods of the 1920s and 1930s — lots of the food culture was weird, but they also had like, just tons of lard and pie. 

Second, if the problem is that Doritos and Kraft Singles have been hyper-engineered by food scientists to be irresistible, then how exactly would the potato diet pry people away from them? If they are irresistible, then it should be really really hard to stop eating doritos and start eating potatoes. But people say that it doesn’t take much or even any willpower to stay on the potato diet, and many people report no cravings. If your model is “people eat the most delicious foods available and cannot help themselves”, then the only way the potato diet could hold people’s attention is if straight potatoes are more delicious and addictive than twinkies. 

Frankly we think they are more delicious than twinkies — but if that’s true and food reward is the law of the brain, then fast-food companies should be peddling baked potatoes instead of Snickers bars. 

Finally, the food reward perspective predicts that the potato diet works because potatoes are boring so you don’t want to eat them. We think this is also bunkum. Potatoes are great, and everyone knows it. Lots of participants reported not only enjoying potatoes, but liking them more after completing four weeks of the study:

(24235303) I didn’t mind eating potatoes.  They were still perfectly tasty throughout, and varying form factor and spices kept things fresh enough.

(02142044) I felt a sort of euphoria/hypomania that lasted from day 17 to day 20, and I’m unsure how to reproduce it … It was both a feeling of well-being, but also the potatoes started feeling delicious, like they were extremely savory.

(29550957) The last two days my family forced me to eat a bunch of other stuff for my birthday and honestly I wasn’t super enthusiastic about it! I wish I could have just been eating more potatoes. I notice I definitely felt worse after eating stuff like cake, and actually felt durably very stuffed for hours afterwards.

(31497197) Overall, I’d say the diet “works” in that I ate as much as I wanted, mostly didn’t crave other food too often, never got sick of potato, and lost weight.  On the very relaxed diet, I lost an average of 2lbs/week, and I think that would have been higher with less frying, but commercial food is not conducive to diets at the best of times. … This is really easy, in that I don’t hate potatoes and haven’t gotten sick of them.

(16832193) I was quite surprised that I didn’t get tired of potatoes. I still love them, maybe even more so than usual?!

Participant 57875769, Day 11: 

My wife and I went out to eat with a friend and I expected to use today as a cheat day, but honestly potatoes sounded like the best thing on the menu so I ordered hash browns and french fries. The hash browns were very filling on their own so I didn’t eat many of the fries.

And again Day 29: 

I’m ending today. It’s weird though, I’m thinking of all the foods I could eat today and I might just stick with potatoes for a lot of my meals. It’s going to feel strange going back to a more varied diet.

So, people come out of the diet saying they love potatoes. Many of them choose to keep eating potatoes even though they’re off the diet. Some of them say they MISS eating so many potatoes. If this isn’t what people mean by “food reward” or “palatability”, then we’re not sure what they mean. If people do mean something else specific, we’d be interested in hearing that.

Same thing for satiety. Yes, potatoes are high satiety, in the sense that you don’t want to eat anything else after you eat potatoes. But why are they high in satiety? Why do they make you not want to eat any more? This is borderline circular reasoning. 

Microbiome

Some people think that the obesity epidemic is caused by some kind of problem with the microbiome, the little beasties that live in your digestive system. 

Microbiome theorists have been in contact with us and have shared how they think potato starch is great for the microbiome, pointing us to studies like this one and popular science posts such as this

This is really a proposed mechanism, rather than a theory of the cause(s) of the obesity epidemic. It doesn’t explain why the microbiome gets so messed up in the modern environment, but this also means it is potentially consistent with many different theories. If high levels of sugar, fat, light exposure, iron supplements, PFAS, lithium, processed foods, or whatever mess up the microbiome, and something in potatoes fixes it, the potato diet would work just about like we see here.

This seems reasonably plausible to us. In particular, many participants report digestive or gastrointestinal changes (both good and bad) on the potato diet, which is about what you would expect if the potato diet were seriously changing your microbiome. One possible limitation is that weight loss does seem to be driven by the brain, but there may be a gut-brain connection that renders this point moot.

That said, we’re not sure how to test this hypothesis any further. We could compare the potato diet to a normal diet supplemented with potato starch, but if the potato starch supplement also caused weight loss, that wouldn’t point to the microbiome specifically, it would just show that the potato starch contains the same active ingredient as the potato diet, whatever that is.

We could also test stool samples, but honestly we don’t know what we would be looking for. Yeah some things would probably change in your microbiome after four weeks of potatoes, and we could see if any of them were correlated with weight loss, but that’s a pretty blunt instrument. What should we actually look for? If anyone has opinions on *exactly* what might be going on with the microbiome, we’d be interested in hearing your theory.

Processed Foods 

“Processed food makes us fat” is a line that has been pushed by outlets such as the Washington Post and the NIH. The basic idea is pretty simple: ultra-processed foods make you fat, for some reason. People who support this perspective don’t usually say what it is about these processed foods that make them so fattening, but it’s often mindlessly conflated with the food reward theory:

It also doesn’t mean that all processed food is bad. Whole-grain bread and cereal are excellent, and there are good versions of such things as frozen pizza and jarred pasta sauce. Also wine.

What it does mean is that modern industrial food processing — and only modern industrial food processing — has enabled the manufacture of the cheap, convenient, calorie-dense foods engineered to appeal to us that have become staples of our obesogenic diet.

This perspective does seem to predict that the potato diet should cause weight loss, because potatoes are super unprocessed, about the rawest food most people are likely to eat. Participant 20943794 does a nice job pointing out just how unusual potatoes are in this way:

Potatoes are a lot less processed than most food I eat … even the dishes I “make” “myself” have a big pre-made components. For example, when I “make” spaghetti, I used dried noodles that were made in a factory, a jar of sauce that was made in a factory, and beef that was butchered in ground in (at least) an industrial kitchen, if not another factory. The only stuff that’s really raw is the vegetables I chop and add.

So at first glance, the potato diet looks good for the idea that processed foods make you fat.

But there are some problems. First off, even if processed foods make you gain weight, that doesn’t necessarily mean that unprocessed foods will make you lose weight. Foods high in cyanide will kill you, but foods low in cyanide won’t bring you back to life (as far as we know, maybe someone should check). 

We also want to say, we really think this is a non-theory. Even assuming processed foods do make you fat, this isn’t a theory (in our opinion) because it doesn’t address the question of WHY processed foods make you gain weight. 

For comparison: in this study, we’ve found that eating enough potatoes makes you lose weight. But “the potato theory” isn’t a good explanation for the potato diet; we want to know what about potatoes makes this happen! So we really demand to know what it is about processed food that (potentially) makes people gain weight. Treating “processed foods” as a theory itself is at best circular reasoning (“processed foods make you fat because they are processed foods”). 

Not to say that there aren’t potential versions of this idea that do work as a theory. Processed foods might be uniquely low in nutrients that we need to stay lean (potassium?). Or, since they spend so much time in contact with industrial machinery, they might be especially high in obesogenic contaminants.

Contamination

There are all kinds of contaminants in the environment that didn’t used to be there. We know that some chemicals can cause weight gain in humans and animals. With these two facts in mind, we think it stands to reason that the obesity epidemic could be caused by one or more contaminants that are getting into our brains and messing up our ability to properly regulate our body weight. We presented a version of this theory in our book/series A Chemical Hunger, and while we don’t think it’s a sure thing, we do think that there’s a lot of evidence in favor. 

The potato diet is definitely consistent with the contamination theory. Since potatoes are so incredibly unprocessed, they are presumably unusually low in most contaminants. Whatever contaminant you might be concerned about, there is probably less in a plain baked potato than there is in a steak, candy bar, or box of pasta. 

The main wrinkle here is that weight loss on the potato diet is so fast, which is a little weird if we assume that the obesity epidemic is caused by contaminants. It seems like something about the potatoes would have to either stop the contaminants from messing with your lipostat, or would have to rapidly flush the contaminants from your body. 

Lithium

We think lithium may be one contaminant contributing to the obesity epidemic (we covered this in Part VII and Interludes G, H, and I of A Chemical Hunger, and we published some correspondence with a specialist here).

Briefly, the lithium hypothesis looks plausible because lithium causes weight gain at clinical doses, and we know people are exposed to more lithium now than they were back in the 1960s. The only thing is, how much lithium do you need to get exposed to before you start gaining weight, and are we getting exposed to at least that much? We’re working on answering these questions, but we have found some evidence that people get exposed to quite a bit in their food (though it’s complicated). 

The fact that the potato diet causes weight loss isn’t really strong evidence for or against the lithium hypothesis. But we do want to point out, it’s consistent with the lithium hypothesis.

Potatoes are high in potassium, and there’s evidence that potassium competes with lithium in the brain in interesting ways. If obesity is caused by your brain getting all gummed up with lithium, and potassium makes it stop, then the high levels of potassium in potatoes would be the sort of thing that might cause lots of rapid weight loss.

Participant 02142044 mentioned this hypothesis: 

You probably already know this, but I find it credible a potential reason as to why the diet works, if it does, is that it is helping clear lithium, which would also help explain the mild hypomanias people experience. https://jasn.asnjournals.org/content/10/3/666 seems to indicate that potassium and sodium can help with clearing lithium. That is also why I started salting more.

The fact that the potato diet causes hypomania in some people and fear & grief effects in others is also maybe consistent with lithium, since lithium is both an antimanic and a sedative.

Another mark in favor is that we do have some idea of what foods may be high in lithium, and there are a few hints that these foods can boot people out of potato mode and stop their weight loss. In particular, we have reason to think that tomatoes are often high in lithium, and one of our participants reported this: 

Another food group that we think is often high in lithium is dairy, and there’s again some evidence that eating dairy can limit the potato diet. Consider this story from participant 29550957:

This is pretty much the best diet I’ve ever been on, including earlier this year when I also ate mostly potatoes- but with tons of dairy (butter, sour cream, cheese) on them. Despite literally messing up an entire week’s worth of days, I seem to be durably down about 10lbs.

If this is the case, then cheating on foods that are low in lithium should always be fine, and may explain why people were able to cheat on this diet so much and still see the effects.

Cheating on foods that CAN be high in lithium is a gamble. A crop that concentrates lithium won’t grab much if it’s grown in a lithium-poor environment, but will be totally loaded if it’s grown in a lithium-rich environment. So it’s quite possible that that e.g. some ketchup is loaded with lithium and some isn’t, depending on where it was grown, how it was processed, etc. This would look like ketchup making a huge difference for some people and not at all for others.

Unfortunately we still don’t have a great list of which foods are high and which are low in lithium. The list we do have, we don’t particularly trust, which is why we are gonna do our own survey of the food supply.

However if we had to guess right now, our best bets for foods that are high in lithium (and if this hypothesis is correct, might inhibit the potato diet) are: Eggs, milk, soft cheeses (but maybe not butter or hard cheese?), anything containing whey, tomatoes, goji berries, leafy greens, beef, pork, carrots, and beets. But again, this list ain’t gospel. 

One point against the lithium-potassium hypothesis is that participant 23300304 sent us blood work from both before and after the diet, and his potassium levels only went from 4.0 mmol/L to 4.5 mmol/L, both within the normal range. But blood levels may not be relevant, since this kind of thing tends to be under tight biological control, and of course we know that potatoes are high in potassium.

If the lithium-potassium competition hypothesis is true, other high-potassium, low-lithium diets might also cause weight loss. There’s a little bit of evidence that potassium consumption is related to successful weight loss, which makes this seem plausible. 

But straight potassium supplementation may or may not work. At first we thought you could just give people potassium salt and see what happened, but we talked to a specialist who studies lithium clearance from the brain, and he said that the bioavailability of potassium from different sources complicates this a lot. We’re still trying to figure out what a good design for this study would be, but it’s not necessarily as simple as “consume a lot of potassium, avoid tomatoes and whey, and lose a lot of weight”, though we suppose someone could try it and see. 

Looking at lithium and potassium in the urine of someone doing the potato diet might help with this, and so we’re considering asking for urine samples in future studies. But it might also be inconclusive.

For example, maybe lithium raises your lipostat set point by gumming up the brain somehow, and high levels of potassium lower the set point by increasing lithium clearance and forcing it all out of the brain. Lithium that gets forced out of the brain has to go somewhere, and if this were the case, it would probably end up in the urine, so you would see elevated levels of lithium in people who enter potato mode.

But maybe lithium causes obesity by forcing potassium out of the brain, and high levels of potassium cure obesity by supplementing potassium faster than the lithium can clear it. If something like this were the case, you might not see more lithium in people’s urine when they go on the potato diet. 

Probably neither of these explanations are exactly correct — these are just examples to show that urine tests during the potato diet might be a good idea, but won’t be conclusive. 

Something else about Potassium

But it’s also not like potassium and lithium are married. Potassium could still cause weight loss even if the lithium hypothesis is totally wrong. Potatoes are notorious for being high in potassium, so it’s reasonable to suspect that this might be the active ingredient.

That said, if it’s not lithium, why would potassium cause weight loss? We don’t know. Any ideas? 

Don’t most theories predict weight loss on the potato diet?

Well, yes and no. Many theories do predict weight loss on the potato diet; but most theories don’t predict potato mode, this state where hunger disappears and you (occasionally) feel charged with incredible energy.

Finally, to anyone who thinks they knew it would work in advance… 

Ok wise guy. 

If you predicted (or could have predicted) that the potato diet would cause this kind of weight loss, or if medical / nutritional science could have predicted that this diet was going to be so effective in the short term, and so easy for so many people — then why haven’t doctors and nutritionists been recommending the potato diet to people alongside diet and exercise?

Why did all these popular press articles have doctors and nutritionists throwing a fit about how dangerous and unhealthy the potato diet would be? Look at these comments they got on stories about Andrew Taylor, who lost over 100 lbs on the potato diet:

“I personally would not recommend it,” says Dr. Nadolsky. “It’s very restrictive. A vegan diet is very restrictive and a ketogenic diet is very restrictive, but a potato diet is one of the most restrictive diets you could ever do.” … the diet itself would be very hard to stick with for most people, says Dr. Nadolsky.

Or this, from a story about Penn Jillette

This type of extreme diet can pose serious health risks due to its severe limitations. “While there’s no doubt that potatoes — just like all vegetables — are supremely nutritious, eliminating almost all other food groups in totality is not only dangerous, but can really backfire,” says Jaclyn London, M.S., R.D., Nutrition Director at the Good Housekeeping Institute.

If you knew the potato diet would work, why did you not run this study many years ago? Why are there no clinical trials? Did you think people would not be excited to see this result? 

Guess the NIH is too scared of the tater.

8. How to Potato Diet if you want to Potato Diet

We’re not currently accepting signups, but we know that some of you will want to try the potato diet for yourselves. So here is some current advice, from us and from some participants.

First, our advice:

  • When you start off, try eating mostly (> 95% of your calories) potatoes, with a little oil, and as much hot sauce and salt as you want. You can also have zero-calorie beverages like black coffee and tea. This seems really strict but many people find it to be much easier than they expected, so give this version a try first. 
  • If you feel bad/weird and are like “I can no longer stand potatoes!”, try:
    • Eating a potato. Hunger feels different on this diet and you may not realize that you are hungry. Yes, really. 
    • Drinking water. It’s really easy to get dehydrated on this diet, and again you can’t always tell. 
    • Eating a different kind of potato. There are many varieties, try mixing it up. You will almost certainly want to eat more than one kind of potato.
    • Peeling your potatoes. Eating less peel / no peel seems to help some people with digestive and energy issues, especially after a few days on the diet. 
    • Eating more salt. Potatoes are naturally low in sodium and you may not be getting enough. 
    • Getting sunlight. Potatoes have no vitamin D, you may be craving that.
    • If none of these other things help, do a cheat meal and eat whatever you’re craving. (But maybe still avoid dairy?) If you find you keep taking cheat meals, go ahead and drop down to the 80%, 60%, or even a lower % potato diet. The 40% potato diet works just fine for some people. 
  • If you still feel bad after trying these steps, stop the diet. If you are suffering then the diet isn’t working anyways, and you shouldn’t take risks with your health. Plus life is too short to do things that make you miserable.
  • If the diet is easy but you’re not losing weight (or otherwise not seeing effects), try doing 100% potato, no oil.

And here’s some advice from participants:

(33217580) I found that despite all the warnings, it was really easy to underprepare and end up with not enough food. The days where I either had done enough prep or just had time to go cook were definitely much simpler than the days where I would have been happy to just eat some boiled potatoes, but sadly the tupperware was empty, and I got really hungry, ate chips or fries, was a little lower on energy or moodier etc. If I’m going to continue (and I might, because it worked so well!), I’m going to aim for comically large  proportions in food prep, because then I might actually have something close to enough.

(31664368) Advice: figure out a way to exit the diet gracefully. I have a robust belly, but significant GI issues I am still going through. Perhaps it was 1 thing I ate that set things on a bad track for several days. Trying oatmeal and crackers as easy non-potato food, but would love a playbook of how to get back to feeling solid after eating a burrito.

(14122662) If I were doing this again, I might also invest in a nice knife. I noticed that chopping the potatoes each day was effortful and a strain on my hand. Being able to slice through the potatoes more cleanly would have been a nice convenience.

(63187175) It requires a lot of preparation and staying ahead of your meals. Potatoes aren’t something you can just grab out of the cupboard and eat, there’s always some amount of cooking required and (at least in my limited experience) that cooking is either quite labor or time intensive (and usually both). If I do this again, my main takeaway lesson is that to be successful in sticking to it, I need to very deliberately over-prepare and always make way more than I want at a time. Just-in-time preparation is way too hard to follow. When I get home from a long day at work and discover that there are no potatoes already made, those were always the moments when I absolutely hated this diet. Even worse, I ran out of potatoes many times during these 3 weeks and had to take a trip to the store before I could even start cooking. Another area where I’d be more diligent if I try this again.

(02142044) How I’d do it again

– Ensure that my weighing scale is reliable

– Keep not using oil

– Stick to the diet strictly throughout

– Only eat potatoes boiled in their own water (mostly or only yellow?).

– Buy them in bio market if possible?

– Probably still eat sweet potatoes weekly for vit A?

– No exercises during this period.

– Do it in a period with less changes in my life overall (no medication, no changing location in between, no big relationship changes, etc)

– Keep filtering water throughout

– Change the way I track thing:

  * Note how much kg of potatoes I eat each meals.

  * Change “Mood” to “Lowest low”, “Highest high”, “Irritability”, “Fluctuation” and “Highest calm/plenitude”

  * Keep track of “How tired am I of this diet?”

  * Also note what is happening in my life to see other kinds of corelations.

– Supplement in B12 way more, salt my meals from the beginning

– No garlic. Cayenne pepper and tabasco are okay

(81125989) Advice to others trying the diet:

Feeling lazy? Trader Joe’s olive-oil Kettle-cooked potato chips for the win. Only three ingredients – potato, olive oil, and salt.

Choose cooking methods that are very low-prep-time, yet high-bulk. At first, I sliced potatoes before baking – this took over an hour each time and only made enough for one meal. Eventually, I realized I could just cut slits in whole potatoes, coat ’em in olive oil & salt, and dump ’em in the oven. Easy & makes enough for 2 days.

Variety is the spice of potato life. Get different kinds of potato, or you will get so intensely bored. (Also, get sweet potatoes for Vitamin A. Maybe placebo, but I noticed my evening low-light vision got worse, but improves the day after I eat sweet potato)

Schedule cheat days? I’ll have to wait to see your full analysis on the dose-response of the potato diet (weight loss vs days cheated)… but if the dose-response is good, then I recommend scheduling cheat days to stave off boredom. (Also, for social eating.) In particular, I ate red meats to get my B12. You can also eat liver or clams. Also potato has no Vitamin D, go get lots of sun or eat dairy/fatty fishes. (I don’t trust supplements; every time I’ve looked at a pre-registered RCT of a vitamin supplement, it’s either near-zero or somehow way less than just eating a whole food that’s known to be a source of it.)

(31497197) Howtos:

 – Buy lots of potatoes.  Bake off or boil off five or ten pounds every couple days, then refrigerate to eat, mash, fry as wedges, roast as cakes, etc.  

 – Takiea baked potato that can be microwaved as needed, and or a small tupperware thing of mashed potato with some chilli/garlic/hot sauce in it when going places for long enough that being hungry will come up, but tables/utensils/microwaves etc will be available.

 – Properly flavored mashed can be used as a dip for potato chips or something when going camping, etc.

 – If with a group at a restaurant, order fries, or just have a beer.  The mashed potato might be full of dairy fat.

 – When eating non-potato snacks, make a note and carry on.  Make sure they aren’t dairy.  

 – Make peace with breaking the diet for a meal every so often.  It will happen sooner or later.  Try not to, but eventually (group camping, or a nice restaurant, or something) it will be better to break the diet than not.  Do so, and get back on potato immediately afterwards.

(21112694) While I only did about five whole days of the diet, I would highly recommend a 1-2 day transition off the diet. The day I ended, I went out for an event and had a large dinner which my digestive tract was not ready for. I typically have no issues with my GI tract, so I figured it wouldn’t be an issue given the shorter diet period. It could have just been a one-off random occurrence, but if you see this trend pop up more, it may be beneficial to suggest a slower transition off the diet, especially for those with GI issues like IBS (I don’t have any). 

9. What’s Next

We’re very happy with this study, but there are some major limitations. Almost all of our participants were white, and most of them were Americans. We expect these results will generalize to other groups in other contexts, but frankly it’s not in the data. 

The potato diet definitely causes weight loss, but a few major questions remain. Questions like, why do some people hit a wall immediately, and find the diet impossible after only a few days? Why do a few people suddenly hit a wall after about 3 weeks?

What’s up with cheat days? Does the 80% potato diet work for everyone? Can some people lose weight on the 40% potato diet? What about the 20% potato diet? The SMTM author who tried the potato diet didn’t lose any weight until they cut out all oil, at which point they started losing about a pound a day. So for some people it seems like the 100% potato diet is really necessary? Is that true? Why would that be? 

Is the attrition rate really higher, and is the diet more difficult, for women / people with two X chromosomes? If so, why? What about trans people? If there’s a chromosomal effect, how does it interact with exogenous hormones?

All of these are questions that would be good to answer in future work.

Our current plan is to follow up with our participants in 6 months, 1 year, and 2 years (assuming it’s still interesting/relevant at that point). We’ll make posts with those results, and share the data publicly, as these followups happen, so look for the first followup post about six months from now.

We may also go back into these data and do more analyses, since there are almost certainly more things to find in the data we’ve already collected. 

Also, expect a forthcoming post on reflections about doing this kind of shoestring internet science. Keep your eyes peeled.

weirdly large number of image search results for “winking potato”

We’re not currently taking signups, but if you want to try the potato diet for yourself, why not track your data using a structured spreadsheet, so all resulting data will be standardized. You’re welcome to download a copy of THIS FORM and follow the instructions, and you can send us an email with your copy of the form when you’re done. Just include the words “Potato Diet” in the email title so the emails are easy to sort and track.

If we can secure funding, our next study may be “potato camp”, a project where we send 20 or more overweight & obese volunteers to a summer camp and serve them nothing but potatoes for four weeks. This would allow us to replicate these results in a slightly more controlled fashion, collect things like urine and serum samples, and so on. And it would be a pretty good deal for participants — we’d make sure there’s wifi, so if you have a remote job, you can just drop by for four weeks and keep working as normal. If you’d be interested in attending potato camp, SIGN UP HERE. If you’d be interested in funding this project, contact us

We might also run other studies, but we’re still figuring out what would be the best and most fun use of our time. Maybe we will run something on potassium. Or maybe our next study will be unrelated to obesity, it’s not the only interesting research topic in the world.

If you would like to be notified of future stupid studies like this one, SIGN UP HERE. You can also just subscribe to the blog itself by email (below), or follow us on twitter, if you want to keep up with our work in general.

And if you feel like reading this post has added a couple of dollars’ worth of value to your life, or if you have lost weight on the potato diet and you think it improves the quality of your life by more than one dollar a month, consider donating $1 a month on Patreon

Thanks for going on this journey with us.

Sincerely, 
Your friendly neighborhood mad scientists,
SLIME MOLD TIME MOLD

[PEER REVIEWED BY ADAM MASTROIANNI]


End Note: Academics, you may cite this report as–

Time Mold, S. M. (2022). LOSE 10.6 POUNDS in FOUR WEEKS with this ONE WEIRD TRICK Discovered by Local Slime Hive Mind! Doctors GRUDGINGLY RESPECT Them, Hope to Become Friends. SLIME MOLD TIME MOLD.

Every Bug is Shallow if One of Your Readers is an Entomologist

The Cathedral and the Bazaar is an essay/book about how Linus Torvalds threw all the normal rules of software out the window when he wrote the operating system Linux

Back in the day, people “knew” that the way to write good software was to assemble an elite team of expert coders and plan things out carefully from the very beginning. But instead of doing that, Linus just started working, put his code out on the internet, and took part-time help from whoever decided to drop by. Everyone was very surprised when this approach ended up putting out a solid operating system. The success has pretty much continued without stopping — Android is based on Linux, and over 90% of servers today run a Linux OS.

Before Linux, most people thought software had to be meticulously designed and implemented by a team of specialists, who could make sure all the parts came together properly, like a cathedral. But Linus showed that software could be created by inviting everyone to show up at roughly the same time and place and just letting them do their own thing, like an open-air market, a bazaar.

Let’s consider in particular Chapter 4, Release Early, Release Often. One really weird thing Linus did was he kept putting out new versions of the software all the time, sometimes more than once a day. New versions would go out with the paint still wet, no matter how much of a mess they were.

People found this confusing. They thought putting out early versions was bad policy, “because early versions are almost by definition buggy versions and you don’t want to wear out the patience of your users.” Why the hell would you put out software if it were still crawling with bugs? Well,

Linus was behaving as though he believed something like this:

> Given a large enough beta-tester and co-developer base, almost every problem will be characterized quickly and the fix obvious to someone.

Or, less formally, “Given enough eyeballs, all bugs are shallow.” I dub this: “Linus’s Law”.

This bottom-up method benefits from two key advantages: the Delphi Effect and self-selection.

More users find more bugs because adding more users adds more different ways of stressing the program. This effect is amplified when the users are co-developers. Each one approaches the task of bug characterization with a slightly different perceptual set and analytical toolkit, a different angle on the problem. The “Delphi effect” seems to work precisely because of this variation. In the specific context of debugging, the variation also tends to reduce duplication of effort.

So adding more beta-testers may not reduce the complexity of the current “deepest” bug from the developer’s point of view, but it increases the probability that someone’s toolkit will be matched to the problem in such a way that the bug is shallow to that person.

One special feature of the Linux situation that clearly helps along the Delphi effect is the fact that the contributors for any given project are self-selected. An early respondent pointed out that contributions are received not from a random sample, but from people who are interested enough to use the software, learn about how it works, attempt to find solutions to problems they encounter, and actually produce an apparently reasonable fix. Anyone who passes all these filters is highly likely to have something useful to contribute.

Linus’s Law can be rephrased as “Debugging is parallelizable”. Although debugging requires debuggers to communicate with some coordinating developer, it doesn’t require significant coordination between debuggers. Thus it doesn’t fall prey to the same quadratic complexity and management costs that make adding developers problematic.

In practice, the theoretical loss of efficiency due to duplication of work by debuggers almost never seems to be an issue in the Linux world. One effect of a “release early and often” policy is to minimize such duplication by propagating fed-back fixes quickly.

Research is difficult because reality is complex and many things are confusing or mysterious. But with enough eyeballs, all research bugs are shallow too.

Without a huge research budget and dozens of managers, you won’t be able to coordinate a ton of researchers. But the good news is, you didn’t really want to coordinate everyone anyways. You can just open the gates and let people get to work. It works fine for software!

The best way to have troubleshooting happen is to let it happen in parallel. And the only way to make that possible is for everyone to release early and release often. If you sit on your work, you’re only robbing yourself of the debugging you could be getting for free from every interested rando in the world. 

In the course of our obesity research, we’ve talked to water treatment engineers, social psychologists, software engineers, emeritus diabetes researchers, oncologists, biologists, someone who used to run a major primate lab, multiple economists, entrepreneurs, crypto enthusiasts, physicians from California, Germany, Austria, and Australia, an MD/PhD student, a retired anthropologist, a mouse neuroscientist, and a partridge in a pear tree a guy from Scotland

Some of them contributed a little; some of them contributed a lot! Every one had a slightly different toolkit, a different angle on the problem. Bugs that were invisible to us were immediate and obvious to them, and each of them pointed out different things about the problem.

For example, in our post recruiting for the potato diet community trial, we originally said that we weren’t sure how Andrew Taylor went a year without supplementing vitamin A, and speculated that maybe there was enough in the hot sauces he was using. But u/alraban on reddit noticed that Andrew included sweet potatoes in his diet, which are high in vitamin A. We totally missed this, and hadn’t realized that sweet potatoes are high in vitamin A. But now we recommend that people either eat some sweet potato or supplement vitamin A. We wouldn’t have caught this one without alraban.

In another discussion on reddit, u/evocomp challenged us to consider the Pima, a small ethnic group in the American southwest that were about 50% obese well before 1980, totally bucking the global trend. “What’s the chance that [this] population … [is] highly sensitive and equally exposed to Lithium, PFAS, or whatever contaminants are in SPAM or white bread?” evocomp asked. This led us to discover that the Pima in fact had been exposed to abnormal levels of lithium very early on, about 50x the median American exposure in the early 1970s. Before this, lithium had been just one hypothesis among many, but evocamp’s challenge and the resulting discoveries promoted it to the point where we now think it is the best explanation for the obesity epidemic. Good thing the community is helping us debug!

My original formulation was that every problem “will be transparent to somebody”. Linus demurred that the person who understands and fixes the problem is not necessarily or even usually the person who first characterizes it. “Somebody finds the problem,” he says, “and somebody else understands it. And I’ll go on record as saying that finding it is the bigger challenge.”

This is a classic in the history of science. One person notices something weird; then, 100 years later, someone else figures out what is going on. 

Brownian motion was first described by the botanist Robert Brown in 1827. He was looking at a bit of pollen in water and was startled to see it jumping all over the place, but he couldn’t figure out why it would do that. This bug sat unsolved for almost eighty years, until Einstein came up with a statistical explanation in 1905, in one of his four Annus Mirabilis papers. Bits of pollen jumping around in a glass of water doesn’t sound very interesting or mysterious, but this was a big deal because Einstein showed that Brownian motion is consistent with what would happen if the pollen was being bombarded from all sides by tiny water molecules. This was strong evidence for the idea that all matter is made up of tiny indivisible particles, which was not yet well-established in 1905!

Or consider DNA. DNA was first isolated from pus and salmon sperm by the Swiss biologist Friedrich Miescher in 1869, but it took until the 1950s before people figured out DNA’s structure. 

Complex multi-symptom errors also tend to have multiple trace paths from surface symptoms back to the actual bug. … each developer and tester samples a semi-random set of the program’s state space when looking for the etiology of a symptom. The more subtle and complex the bug, the less likely that skill will be able to guarantee the relevance of that sample.

For simple and easily reproducible bugs, then, the accent will be on the “semi” rather than the “random”; debugging skill and intimacy with the code and its architecture will matter a lot. But for complex bugs, the accent will be on the “random”. Under these circumstances many people running traces will be much more effective than a few people running traces sequentially—even if the few have a much higher average skill level.

This is making an important point: if you want to catch a lot of bugs, a bunch of experts isn’t enough — you want as many people as possible. You do want experts, but you gain an additional level of scrutiny from having the whole fuckin’ world look at it.

Simple bugs can be caught by experts. But complex or subtle bugs are more insane. For those bugs, the number of people looking at the problem is much more important than the average skill of the readers. This is a strong particular argument for putting things on the internet and making them super enjoyable and accessible, rather than putting them in places where only experts will see them.

Not that we need any more reasons, but this is also a strong argument for publishing your research on blogs and vlogs instead of in stuffy formal journals. If you notice something weird that you can’t figure out, you should get it in front of the scientifically-inclined public as soon as possible, because one of them has the best chance of spotting whatever you have missed. Back in the day, the fastest way to get an idea in front of the scientifically-inclined public was to send a manuscript to the closest guy with a printing press, who would put it in the next journal. (Or if possible, go to a conference and give a talk about it.)

But journals today only want complete packages. If you write to them about the tiny animals you found in your spit, they aren’t going to want to publish that. Times have changed. Now the fastest way to get out your findings is to use a blog, newsletter, twitter, etc.

Job Posting: Reddit Research Czar

Job postings are a kinda weird phenomenon. For one thing, they’re very modern. It used to be that most people either inherited a job (I’m a baker because my pa was a baker and our tiny hamlet needs a baker) or noticed an opportunity and ran with it (lots of hungry travelers cross that bridge every day, I bet I could make a living selling pancakes).

We’re talking about the second thing today, the opportunity just waiting for someone to snap it up. This is a job posting, but we’re not hiring. Reddit is hiring. Well, not REDDIT. The abstract spirit of reddit is hiring. The universe is hiring. 

hmmm yes

Let us try to explain.

Czar was originally a term for East and South Slavic monarchs, most notably the Russian emperor — it’s another spelling of Tsar and yet another corruption of the Roman title Caesar, just like Kaiser. But at some point in the middle of the 20th century it became a term in the US and UK for government officials “granted broad power to address a particular issue”. The Industry Czar is in charge of industry, the Milk Czar is in charge of milk, the Asian Carp Czar is in charge of Asian Carp (no, really), and so on and so forth.

Carp Czar Gone Wild

There are lots of problems in the world; some are covered, but there are many others where existing institutions have totally dropped the ball. Often, more research would help. But the academy just doesn’t move as fast as it used to. If you’ve ever looked at something and been like, “someone should do a study”, you know what we mean.

Reddit is a bizarre, amazing place. Literally millions of people have come together to this place on the internet and self-sorted into about 3.4 million communities, called subreddits. True, many subreddits are dedicated to very niche porn or insane crypto schemes. But if you want to build a desktop gaming rig, get male or female fashion advice, or discover long, plush horrors, there’s a subreddit for that. You can learn so much about any topic or hobby, maybe too much if you’re not careful (compare). 

We’d like to apologize to the ghost of Alan Turing

This means there are lots of special populations on reddit, people who have a condition or illness, maybe a rare one, who are extreme outliers (e.g. very tall and/or live in a submarine), or who have a burning obsession with some niche idea. Subreddits bring people together, to commiserate, to try to help each other solve a problem, or to post insane fanart.

These people are all very interested in their shared topic. They are all highly motivated. Many of them are ready to self-experiment, or are already self-experimenting. A lot of things count as self-experimentation. If you’re doing a diet, or trying to get more sunlight, or even just trying to drink more water, that’s self-experimentation too. So a subreddit for a given problem or topic is a powder keg of interest and motivation, just waiting for a spark. 

Because while subreddits are very motivated, they’re largely untapped for organized research. Even in subreddits with good leadership, it’s rare for the leadership to have a research background. Most communities lack someone with the methods skills to design a good study, and the statistical analysis skills to examine the data afterwards. 

If you have these skills, and you are familiar with reddit, you could show up and start helping people organize research. You could collaborate with people to help them solve their problems, or at least learn more about their problems, and you could start doing it tomorrow. 

Redditors could never be coordinated enough to pull off something as complex as scientific research!

Crowdsourcing research like this is under-explored. Almost no one has ever done studies organized like this, so in our opinion, there’s virtually guaranteed to be low-hanging fruit all over the place. Anything that isn’t sexy enough for a major journal or doesn’t sound serious enough for the NIH to spend their time on is ripe for the picking.

The current research world is very narrow-minded. Doctors and researchers are quick to blame a person’s behavior or hygiene and very slow to blame environmental contaminants. If you’re more creative or more open-minded, and you’re willing to consider other paradigms, you can just move faster. If doctors don’t take the pathogen paradigm for chronic disease and digestive disorders seriously, then by becoming the “Pathogenic Disease Czar”, you might be able to rack up discoveries really quickly.

There’s also the question of “why now”? Part of it is that the research world has slowed down. But another part is that the rest of the world has sped up. We’re more coordinated than ever. Today you can get 100 people reading your latest newsletter in 20 minutes. Today you can pop by a subreddit and consult with thousands of people in a matter of hours. Today you can cold-email an emeritus professor who worked on the problem in the 1970s and be on a Zoom call with them next week. 

Research tools are also opening up, getting more accessible every day. If you’re leading the reddit charge on some rare glandular disorder, it now takes only a couple hundred dollars per person for everyone involved to get their genome sequenced and it’s getting cheaper all the time. If there’s a genetic explanation, or genetics is involved in some way, it’s only recently gotten cheap enough that communities might able to find it on their own.

There are lots of interesting ideas where the only support for them is a single paper with 20 participants from 1994. If you can get a couple dozen volunteers together, boom, you’ve just advanced the state of the field, and discovered whether or not there was anything to that interesting idea.

One example is our own ongoing all-potato diet study, which we see as the first of what will hopefully be a long tradition of community trials and community RCTs (randomized controlled trials). We’ve mostly recruited from twitter for the potato diet, but we just as easily could have recruited from reddit. For reference, this was the response on one subreddit, and not even a subreddit directly related to dieting.

Sometimes just planting a flag in the sand is enough. People like to feel like a part of something and are excited to participate. One participant in the potato diet said:

How do we get stronger evidence [for the potato diet]? Well someone has to go out on a limb and run an experiment. This is a particularly important motivation for me. If this were not part of a larger study, I wouldn’t spend my energy on it (after all, it probably won’t work). But the fact that it might yield useful data makes it much more appealing.

Obesity and related issues (heart disease, diabetes, etc.) is just one example of a serious problem that people are invested in solving. It seems like there are lots of problems where we might be able to quickly learn a lot by rigorous self-experimentation and community research. 

Depression and anxiety are classic unsolved problems. Sure, we have some mildly effective treatments, but why don’t we have great ones? Why does a given treatment work for some people and not others? What about people with treatment-resistant depression? Why are things like exhaustion and brain fog symptoms of depression? Where does depression come from? There’s been a lot of discussion but our take is still “no one knows” or at least, “the jury’s still out”. We see that r/depression/ has over 800,000 members and a couple thousand are usually online at a given time. If you think you could help, they seem like they would be glad to have it. 

Crohn’s disease is debilitating and remains very poorly understood — Wikipedia, for example, says, “While the precise causes of Crohn’s disease (CD) are unknown, it is believed to be caused by a combination of environmental, immune, and bacterial factors in genetically susceptible individuals. …  While Crohn’s is an immune-related disease, it does not appear to be an autoimmune disease (in that the immune system is not being triggered by the body itself). The exact underlying immune problem is not clear; however, it may be an immunodeficiency state.” Sounds like more research is needed, and r/CrohnsDisease/ has 42,000 members.

If that’s not mysterious enough for your taste, there are all the really inexplicable digestive conditions, which go by names like IBS (irritable bowel syndrome) and GERD (gastroesophageal reflux disease). These can really fuck you up, so people will be really motivated to try things and find a treatment. And there might be weird treatments out there that really work. You can drop by r/ibs/ with 74,000 members or r/GERD/ with 42,000 members and start putting out surveys, today if you want! (But talk to the mods first, don’t get kicked out for being a weirdo.)

But you won’t be the first researcher on the scene. We see that u/OrganicSquare made a post titled “Let’s use machine learning to help us find solutions to our reflux. I need this whole community to answer this survey for data!!!” on r/GERD about a year ago. We can’t find the results — maybe she’s still analyzing the data — but this is exactly the sort of thing we’re talking about. OrganicSquare, you are the hero reddit needs, let us know if you want to collaborate.

There are also some populations that will be interesting not because they are facing a problem they want to solve, but because they are special in some other way. Trans people would love to have better resources for transitioning, and you could certainly drop by to help them study that. But we think the real reason to drop by r/TransDIY/ and similar subreddits is because you have literally thousands of people conducting n = 1 endocrinology experiments.

There’s a good chance the next great endocrinologist will be trans, just because of their personal familiarity with the subject and ability to self-experiment. If you want to see what effect testosterone/estrogen/progesterone/estradiol has on mood/energy/digestion/attention/nerve growth/body temperature/whatever, this is one of your few and best chances to get experimental data. 

This is nowhere near a complete list. In fact, please drop other subreddits that might be excited to do more community research in the comments.

It’s more common than you might think

We call this a job posting because we think this could easily be a full-time job. If you help a community or two get closer to solving their problem, even if you just help them coordinate and give them HOPE that their problem is solvable, it would be pretty easy to convince lots of them to chip in. It’s hard for an individual to hire an expert, but some of these communities have tens or hundreds of thousands of members. For a community that size, hiring some full-time research muscle is easy.

You set up a Patreon or a newsletter (we recommend Ghost), and ask for support. If you can get 1000 people to give you $3 a month, that’s $36,000 a year, enough to start thinking about doing this full-time.

You don’t need to solve anything up front. You just need to convince 1000 people that you’re doing enough to justify them spending $3 a month on something they think is important, which is not a hard sell. And if you get 10,000 people on board for $1, you’re even better off. (Incidentally, here is our patreon.)

Crowdfunding is the best and noblest option, but it’s not the only route you can take. Some communities will have a millionaire or two in the ranks, and if you start doing good work, people will come out of the woodwork to help. There are lots of granting agencies out there looking for stunning projects to throw money at. Start coordinating reddit research for a few months, show that you’re serious, make a little progress, and it should be easy to make the case for some grants.

And actually, you might also be able to get funding from reddit, up to $50,000! Starting June 2022, reddit will start distributing one million dollars in community funding to different subreddits. If you can make the case to a subreddit that you can lead their community research for a year, they can apply for $40,000 to be your salary, and there’s a good chance they’ll get it. The article linked above says, “I can’t wait to see what wild project the r/WallStreetBets crew tries to get $50,000 to pull off.” Yeah holy shit.

Finally, if you are financially independent / have a good job that gives you lots of free time, then this is DEFINITELY a job suited for you. You already don’t have to worry about money; maybe you even have enough that you could pay for a statistician / the chemical analysis of samples / new air quality monitors / sundry other research expenses. You’re looking for something interesting to spend your time on, something that also makes the world a better place. If you have the skills and inclination, nothing could be a better fit!

It’s worth touching for a moment on the skills we think would be important. Any research on reddit would probably start with a lot of surveys, so someone with lots of experience with survey-based methods might have the advantage here. Possibly a sociologist or psychologist? But on the other hand, a lot of the problems reddit communities would be interested in solving are medical, so maybe someone with a medical background is the best person for the role. On the other other hand, a lot of the advantage here might be statistical, having the skill to work with big strange datasets, so maybe a data scientist.

Or form a cabal if you want:

Reddit Research Cabal

Anyways, if this is the job you want, and you think you have the skills to do it, there are two general ways to approach this…

Go Specific

If you are a person who is a member of one of these communities, who is inclined towards research and wants to rally people to solve the problem, going specific might be the approach for you.

There are a couple winning examples already, let’s take a look. These two don’t use reddit for the most part — they have communities elsewhere — but it’s not hard to imagine recreating some of their successes in a subreddit rather than on a blog or on twitter.

Scott Alexander is pretty much the research czar for rationalists, in his reader surveys (both back on SSC and now on ACX), and in some more specific work like the nootropics survey. Rationalists aren’t a community with a rare disease to cure, but they are united in their interest in specific topics, like AI, IQ, and birth order effects. And Scott, being a psychiatrist, has a special interest in things like SSRIs. We’re very interested in the small amount of work he’s done on air quality / ventilation, which we’ll note has included at least a little self-experimentation.

Whorelord and “mad social scientist” Aella is kind of de facto sex worker / sex research czar for the whole internet. She also does psychology and psychedelics research, which must be reasonably well-regarded because her twitter followers include some big names in psychology, like Paul Bloom and Uri Simonsohn (and see this interaction). But mostly it’s sex stuff, and the quality of her research puts the average social science publication to shame: 

Scott is a rationalist and Aella has lots of sex / is a (former) sex worker, so they’re perfectly positioned to be the research czars for their communities. We’d recommend that the “go narrow” approach be taken with communities you are a part of as well.

There are clear advantages to going narrow. First off, you can self-experiment. You can pilot-test studies on yourself, and you can show people that you would never ask them to do anything you aren’t willing to try first. You can specialize and learn a lot about this one area of research. And you’ll understand the topic better, because you’ve lived it.

There are also a couple of disadvantages. This has a smaller scope, but some of you might like that. It’s less exciting, and maybe harder to get support and raise money for projects. But it’s also more practical.

Go Broad

The other option is to try to become the Czar of all the Reddits.

In this approach, you try to work with lots of different subreddits, lots of different communities, and try to solve lots of different problems. Instead of focusing on just one mystery at a time, you go broad. 

If you are a generalist with good research chops, who spends a lot of time on reddit and knows how it works, who likes the idea of working with tons of different people, on dozens of projects, this might be the approach for you.

This approach has some clear advantages. If you work on more projects, you will be able to get funding from more quarters. As you try more and more things, you’ll learn a lot about the metascience of doing this new kind of community research. You can switch between projects when you’re waiting for results. If you hit a dead end on one question, you can take some time off and switch to something else. More things to work on means it’s more likely something will be a success.

There are also a few disadvantages. You’ll always risk getting spread too thin, and you will spend lots of time getting familiar with new topics, instead of going deep on just a few. You probably won’t share most of the problems you want to help solve. Since you don’t have these diseases/conditions/whatevers, you won’t be able to self-experiment, and self-experimentation is an important part of research. And some communities won’t want or appreciate help from an outsider.

To Sum Up

Reddit is a big place. There’s a lot of questions to answer, problems to solve, and communities to rally to the mad science crusade. 

Probably by 2030 there will be several major researchers on reddit, and two or three of them will be getting close to being household names. Some of them will be generalists who hop around different subreddits, consulting on different problems. Some of them will be specialists, organizing their communities against shared problems. Different research czars will work together to make bigger and better projects, and problems will get solved faster than anyone today thinks possible. 

But why wait to see other people do it? If you think you have what it takes (or half of what it takes; don’t be afraid to learn on the job), there’s nothing stopping you from doing this starting tomorrow. We’d be happy to consult on stats and methods — and if you do anything interesting, we might blog about it. If you declare yourself Czar of X and you make a big breakthrough, we will send you a crown (though it will not be this nice).

Potato Diet Community Trial: Sign up Now, lol

In French, the word for potato is pomme de terre. This literally translates to apple of the earth. By this logic, potatoes are the lowest-hanging fruit of all.

More seriously: We keep getting more and more interested in the all-potato diet. This is a diet where you eat nothing but potatoes (and sometimes a bit of seasoning) for a few weeks to a few months. It sounds like a dumb gimmick that could never work, but there are a surprising number of people out there saying that they tried it, it worked for them, and they kept the weight off for months or even years after.

Anecdotes are limited in all sorts of ways, but there are a surprising number of very strong anecdotes about the all-potato diet causing huge amounts of easy, sustainable weight loss:

Again, anecdotes by themselves are limited. We don’t know how many people tried this diet and didn’t get such stunning weight loss. We don’t know how long the weight stays off for. And the sample size is really small. Someone should really do a study or something, and figure this thing out.

Well, ok, if you insist. But you all have to help! 

Tl;dr, we’re looking for people to volunteer to eat nothing but potatoes (and a small amount of oil & seasoning) for at least four weeks, and to share their data so we can do an analysis. You can sign up below.

Aren’t there already diets that work? Well, maybe, but we certainly don’t have any that work reliably. Reviews of meta-analyses say things like, “Numerous randomized trials comparing diets differing in macronutrient compositions (eg, low-carbohydrate, low-fat, Mediterranean) have demonstrated differences in weight loss and metabolic risk factors that are small (ie, a mean difference of <1 kg) and inconsistent.” And The Lancet says, “unlike other major causes of preventable death and disability, such as tobacco use, injuries, and infectious diseases, there are no exemplar populations in which the obesity epidemic has been reversed by public health measures.” We could go on like this all day — actually wait, we already did

There are all sorts of crazy fad diets out there that haven’t been formally tested, and many of them have anecdotes that sound at least this good. Some of you may have even tried one. So why are we so interested in this over all the others?

Most diets are unpleasant and require you to use a lot of willpower to eat the right stuff or avoid the wrong stuff. On most diets, people are hungry all the time and feel terrible and gain the weight back as soon as they stop dieting. But the potato diet, at least according to the anecdotes, isn’t unpleasant at all — it’s quite easy. This isn’t a willpower diet. If the diet works, and it’s as easy to stick to as they say, that would be an important finding.

Most diets are hard to follow in that the instructions are precise and/or complicated — you have to eat exactly the right ratio of stuff to other stuff, carefully weigh and measure all your portions, count calories, do a lot of math in your head, check all the ingredients in everything you buy, etc. In contrast, the all-potato diet is really simple. No complex principles. No weighing and measuring your food. No checking ingredients. Just potato.

Some diets claim they won’t work unless you do everything just right. If you don’t lose weight on one of these diets, fans of the diet can always fall back on saying, maybe you did it wrong. In comparison, potato diet is easy. We don’t think it really matters if you accidentally eat a chocolate bar, as long as you are eating mostly potatoes. If you eat mostly potatoes and you don’t lose weight, then the diet doesn’t work, no one will be saying “you did it wrong.”

The potato diet also appears to have a huge effect size — 20 lbs for Chris Voigt, 114 lbs for Andrew Taylor, etc. — which should make it easy to study. We’re not fiddling around with a diet that might make you lose 5 lbs. If most people lose as much weight as Chris and Andrew, that will be really obvious. And if it doesn’t work for most people, well, that’s an important finding too.

Finally, one of the most interesting things about the potato diet is that people seem to keep the weight off afterwards, which is basically unheard of for diets. If we can confirm that in a study, it will be a pretty big deal. 

So that’s why we want to study the potato diet in particular. It should be easy to get a straight answer about this diet. If it works, people will be able to use this diet to lose weight and gain energy, if that’s what they want. And if it works, it probably provides some kind of hint about why the obesity epidemic is happening in the first place. So let’s do a study.

Diet Design

To figure out how to run this study, we needed to figure out what kind of all-potato diet seems to work for weight loss. To do this, we took a close look at the case studies we mentioned above. Some of these accounts are pretty detailed, so we won’t bore you with it up front. If you want more detail, we give an overview of each case study in the appendices.

The overall picture looks pretty clear. The basis of the all-potato diet is, unsurprisingly, eating almost nothing but potatoes.

In the most extreme cases, like Penn Jillette and the Krocks, people appear to eat literally nothing but potatoes, with no seasonings, and drink nothing but water. This seems to work pretty well but sounds like it would be hard to stick to. It’s notable that both of these examples kept it up for only two weeks, though they did lose impressive amounts of weight.

In comparison, Andrew Taylor was able to stick to an all-potato diet for a full year. He let himself use spices and seasonings, drank things other than water, and he still lost more than 100 pounds. He just made sure to take a B12 vitamin and kept away from oil and dairy.

Chris Voigt lost the least weight, but he seems to have had a pretty easy time of it. He was able to lose 21 lbs while using all kinds of salt and seasonings and cooking his potatoes in oil, and he wasn’t even trying to lose weight at all. This suggests, to us at least, that stricter versions of the diet aren’t necessary to see the benefits.

Potatoes are indeed very nutritious (here’s the USDA page for russet potatoes). The official word is that they don’t contain any vitamin A and don’t contain any B12. We’re not sure about the vitamin A — Andrew Taylor went a year without supplementing vitamin A (he did take B12), but maybe he got all the vitamin A he needed from the sauces he used? In any case, a vitamin B12 supplement is appropriate, and a vitamin A supplement seems like a good idea. [EDIT: u/alraban on reddit points out that Andrew ate sweet potatoes, which are high in Vitamin A. This is a good point, so now our recommendation is that you should either include sweet potatoes or take a Vitamin A supplement.] If you take a normal multivitamin you should be totally covered — but again, none of the case studies seem to have needed it.

Based on these examples taken together, our version of the diet is: 

THE POTATO DIET

  • Drink mostly water. You can also have some other beverages. Chris Voigt had coffee, tea, and diet soda. Andrew Taylor sometimes had beer, even. Just don’t take them with cream or sugar and try not to get too many of your daily calories from your drinks. 
  • Eat potatoes. Buy organic if you can, and eat the peels whenever possible. Start with whole potatoes and cook them yourself when you can, but in a pinch you can eat potato chips or fries if you need to. You can calculate how many potatoes to eat (a potato is about 100 calories, so if you need 2000 kcal/day, eat about 20), but we think it’s better to eat the potatoes ad libitum — make a lot of potatoes and just eat as much as you want.
  • Perfect adherence isn’t necessary. If you can’t get potatoes, eat something else rather than go hungry, and pick up the potatoes again when you can. 
  • Seasonings are ok. Chris used seasonings like Tabasco sauce, chives fresh out of his garden, a Thai herb/pepper paste, and bouillon cubes in water for fake gravy. Andrew used seasonings like dried herbs, fat-free sweet chili, barbecue sauce, and soy milk (in mashed potatoes). Do what you can to keep yourself from getting bored.
  • Oil is ok. Chris used it, Andrew and Penn didn’t. You can go either way. In fact, it would be great for us if some of you use oil and others of you don’t, so we can see if there is any difference. If you do use oil, probably use olive oil, which seems to be what Chris used. Maybe consider imported olive oil from Europe, which we suspect contains fewer contaminants, in case the contamination theory is correct.
  • Take a daily B12 supplement, since potatoes don’t contain any. We like this version but use whatever you like. Take vitamin A if you’re not eating sweet potatoes. A multivitamin would also be fine as long as it contains B12. 
  • Everyone seems to agree: No dairy. Maybe this doesn’t matter, but on the off chance this is really important for some reason, please avoid all dairy products. 

If in doubt, pick one of the examples we describe in the appendices and follow their example. You can always ask yourself, what would Chris Voigt do? And then do that.

In the spirit of self-experimentation, and because we were curious, one of us decided to try the all-potato diet for ourselves. That author is currently on day 11 of the all-potato diet. In that author’s own words: 

I was originally going to do just one or two days of the potato diet to see what it was like, but it was so easy that I figured I should try to keep to it for a full week. But it was still easy at a week, and now I’m just curious how long I can keep going for.

I feel fine, totally normal. I don’t feel more energetic than normal, but I’m pretty energetic to begin with. My mood is a little better, and I’m maybe sleeping better. Exercise seems easier, or at least it’s not any harder, kind of surprising when all my protein comes from potatoes. I haven’t lost any weight but I’m not overweight so I didn’t have much to lose in the first place.

It doesn’t require any willpower. I don’t crave anything else, I’m not tempted to buy other food at the grocery store, I’m not jealous when people around me are eating pizza or chocolate. I’m happy to sit down to a pile of potatoes every meal. They still smell delicious. If anything, I like potatoes even more now. The hardest part is the logistics of preparing that many potatoes every single day. 

I’m using European olive oil, salt, spices, vinegar, and a couple of hot sauces to keep the potatoes interesting. I want to say that it would be much harder without them, but honestly, this is so much easier than I expected, I don’t know what to expect anymore. Maybe it would be just as easy without oil and hot sauce.

Here’s my advice based on my personal experience. You should get a wide variety of potatoes. When you’re eating nothing but potatoes, the differences between different varieties become very obvious. At first I was happy with yukon gold but after a few days I began to crave russet potatoes. Make a lot every time you cook, you will eat more than you expect. And make sure to drink lots of water, I keep finding it hard to remember and end up feeling dehydrated.

UPDATE DAY 13: For the last two days I tried nothing but baked potatoes with no oil and barely any spices. It was really easy, I feel super energetic, and I started losing weight. So if the diet isn’t having any effect for you, consider trying it with no oil.

Study Design

That’s the diet we’re thinking of. What about the study design? 

Official-sounding diet studies from like the NIH and stuff don’t always run all their subjects at the same time, so we won’t bother doing that either. We’ve made it so you can sign up and participate in this study at any time. Rolling admissions.

There’s no need for a control group because the spontaneous remission rate for obesity is so low. For example, if someone said they had invented a medicine that could re-grow lost limbs, we wouldn’t need a control group for that trial, because the spontaneous limb regrowth rate is almost exactly zero (in humans anyways). If anyone regrew their arms or legs, that would be pretty convincing evidence that the medicine works as promised. Similarly, people almost never spontaneously drop 20 pounds, so we don’t need a control group.

This is also a trap. We expect that some people will come back with “but there wasn’t a control group!” This is a sign that they didn’t actually read what we’ve written and are boneheads who don’t understand how research works.

We’re not worried about tight experimental control. Maybe this diet would work better in the lab, but what we are actually interested in is how it works when implemented by normal people in the comfort of their home. If it doesn’t work in those circumstances, we want to know that! If the potato diet can’t be used practically, we don’t really care if it works in the lab, we know which side our potato is buttered sprinkled with garlic salt on. If it doesn’t work with this design, it just doesn’t work. And if it does work at home, it would presumably work even better in the lab. 

We’re also interested in the huge effect size described in the anecdotes above. We’re not worried about tiny amounts of noise from things like what you’re wearing or what time of day you weigh yourself. If the experience of Chris Voigt is at all typical — if the average person loses about 20 lbs — these tiny differences won’t matter.

And we’re not all that worried about adherence. If the 100% potato diet works, the 90% potato diet probably works too. So while we prefer that anyone sending us their data tries to refrain from eating any delicious pickles during the diet, if you do eat a pickle, it probably doesn’t matter.

Sign up to Eat Potatoes for the Glory of Science

This looks pretty promising, so let’s try to go past the anecdotes and do this in something like a rigorous fashion. Who wants to eat some ‘taters? 

The only prerequisite for signing up is being willing to eat nothing but potatoes for at least four weeks, and being willing to share your weight data with us.

(And being an adult, having a scale, not being allergic to potatoes, etc. etc.)

One reason to sign up is that you hope this will help you lose weight, lower your blood pressure, make you less depressed, or see one of the other effects reported by people like Chris Voigt and Andrew Taylor. But another reason you might want to sign up is to help advance the state of nutritional science. In a small way, this study will tell us something about nutrition, weight loss, and obesity that we don’t currently know. If the diet works, it will give us a practical intervention that people can use to reduce their weight, which we don’t really have right now.

And beyond that, running a study like this through volunteers on the internet is a small step towards making science faster, smarter, and more democratic. Imagine a future where every time we’re like, “why is no one doing this?”, every time we’re like, “dietary scientists, what the hell?”, we get together and WE do it, and we get an answer. And if we get a half-answer, we iterate on the design and get closer and closer every time. 

That seems like a future worth dreaming of. If you sign up, you get us closer to that future. We hope that this is only the first of what will be a century full of community-run scientific trials on the internet. Maybe by 2030, the redditors will have found a way to triple your lifespan. But for the first study, let’s start with potato.

We understand that eating nothing but potatoes for four weeks sounds pretty daunting. But based on the case studies above, and our own experience, we want to reassure you that it will probably be much easier than you expect. In fact, here’s our suggestion: If you are at all interested in trying it, go ahead and sign up and start collecting your data. Try the first day or two and see how it feels.

If it’s really hard for you to stay on the diet and you just can’t continue, go ahead and stop, just send us an email and close out the diet as normal (see instructions below). We’re interested in the diet as a whole, and if 40% of people can’t stick to the diet for more than two days, that’s important information about how effective the diet is in a practical sense. We’d be happy to have that information. 

But based on our own experience, we suspect that most of you who try it for a couple days will be like, “wow this is so easy! I could do this for a couple weeks no problem.” If that’s how you feel, keep collecting your data and see if you can keep it up for four weeks. 

If you want to go for longer than four weeks, that’s great, we would be happy to have more data.

If at any point you get sick or begin having side-effects, stop the diet immediately. We can still use your data up to that point, and we don’t want anything to happen to you.

If you are taking potassium supplements, often given as blood pressure medications (like Losartan) please take this extra seriously. A diet of 20 potatoes a day will give you about 300% your recommended potassium. While this should be safe by itself, it might be a problem if you are already taking a potassium supplement. Don’t sign up if you have bad kidneys, kidney disease, or diabetes (you can check with your doctor). Be aware of the signs of hyperkalemia.

We are mostly interested in weight loss effects for people who are overweight (BMI 25+) or obese (BMI 30+), but the energy and mental health effects reported in some of the case studies are interesting too. If you are “normal weight” (BMI 20-25) you can also sign up, especially if you want to feel more energetic or you want to tackle depression and anxiety or something. 

And for everyone, please consult with your doctor before trying this or any other weight loss regimen. We are not doctors. We are 20 rats in a trenchcoat. eee! eee! eee!

Anyways, to sign up: 

  1. Fill out this google form, where you give us your basic demographics and contact info. You will assign yourself a subject number, which will keep your data anonymous in the future. [UPDATE: Signups are now closed, but we plan to do more potato diet studies in the future. If you’re interested in participating in a future potato diet study, you can give us your email at this link and we’ll let you know when we run the next study.]
  2. We will clone a version of this google sheet and share the clone with you. This will be your personal spreadsheet for recording your data over the course of the diet.
  3. On the first day, weigh yourself in the morning. If you’re a “morning pooper”, measure yourself “after your first void”; if not, don’t worry about it. We don’t care if you wear pajamas or what, just keep it consistent. Note down your weight and the other measures (mood, energy, etc.) on the google sheet. Then spend day 1 eating nothing but potatoes. On day 2, weigh yourself in the morning, note down data in the sheet, then spend day 2 eating nothing but potatoes. On day 3, etc.
  4. We prefer that you stick closely to the diet for at least four weeks. But if you do break the diet at some point, just note that down in the appropriate column and try to stick to the diet the next day. Again, we’re interested in how the diet works for normal people at home, and so imperfect adherence is ok. If you totally can’t stand the diet, just stop doing it and end the study per the next instructions.
  5. Whenever you are done with the diet (preferably four weeks, or longer if you want, we’re happy to have more data if you are enjoying the diet), weigh yourself and fill out one last morning’s data so we have an endpoint, then stop the diet.
  6. Then, send us an email with the subject line “[SUBJECT ID] Potato Diet Complete”. This will let us know to go grab your data. This is also your opportunity to tell us all about how the diet went for you. Please tell us all the data that doesn’t easily fit into the spreadsheet — how you felt on the diet, what brand of oil you used, what kind of potatoes you bought, where you got them from, what kind of cookware you used, before and after pictures (if you want), advice to other people trying the diet, etc. We think there’s a pretty good chance that this diet will work for some people and not for others, and if that happens, we will dig into these accounts to see if we can figure out why (e.g. maybe this works with olive oil but not with vegetable oil, or something).
  7. If we have our act together, we will send each of you a brief google form following up at 6 months and at 1 year, and maybe at future intervals (5 years?).

Assuming we get 20 or so people, we will write up our results and publish them on the blog. We would really like to get a couple hundred people, though, since at that point it becomes possible to do more complex statistical analyses. So if you think this is an interesting idea, please tell your friends. 

We’ll keep this updated with roughly how many people have signed up and stuff, until we get bored or decide the study is closed:

Signed Up: 220 [CLOSED]

Past the 4-Week Mark: 46

We’re pretty happy with this study design. In particular, we don’t think it’s a weakness that people are doing this at home, since those are the conditions that we actually want to understand the diet under. We want to know how it works when it’s applied like it would actually be applied.

That said, if you are a wealthy donor and you want to fund a more controlled version of this — maybe, send 30 overweight and obese volunteers to a campground in Colorado for a couple weeks and feed them nothing but potatoes while they’re there, and hire a nurse or two to check up on them every day — please contact us. It’d be cheap as far as nutrition research goes, and we’ll make you a mixtape of potato songs.

Appendix A: Super Basic Potato Preparation

Use whatever recipes you want, but here are two very simple ways to prepare them.

Here’s how to roast any kind of potato:

  1. Preheat oven to 425 F.
  2. Spread a thin layer of olive oil on a large cookie sheet.
  3. Wash potatoes and make sure they do not have any dirt or anything gross on them.
  4. Cut off any gross spots on the outside of the potatoes.
  5. Cut the potatoes into any of the following: large fries, slices about a quarter inch thick, or chunks a little bigger than a grape. Do the whole batch with the same method.
  6. If you find any other bad spots while you’re cutting up the potatoes, cut them off and throw them away.
  7. Put the cut potatoes in a large bowl and dress them with olive oil, salt, and whatever seasonings you want (salt, pepper, garlic powder, rosemary, etc.). Mix them so the oil and seasoning is all over the potatoes.
  8. Put the potatoes on the cookie sheet and make sure they are all well seasoned / well oiled.
  9. Put them in the oven for 20 minutes, then take them out and stir them with a wooden spoon or spatula. They will probably stick to the cookie sheet a bit, this is normal.
  10. Put them back in for another 20 minutes and then take them out again. Let one cool and try it, making sure not to burn your mouth. If it seems done and edible, turn off the oven, your potatoes are done. If it still seems a little raw, put them back in for another 10 minutes.
  11. When done, eat with your favorite no-calorie sauces and vinegars.

Here’s how to boil any kind of potato:

  1. Fill a pot with enough water to cover however many potatoes you’re making. Salt the water and set it on the stove on high to boil.
  2. Wash potatoes and make sure they do not have any dirt or anything gross on them.
  3. Cut off any gross spots on the outside of the potatoes.
  4. Cut the potatoes into small chunks. Any size is fine, but smaller chunks will cook faster.
  5. If you find any other bad spots while you’re cutting up the potatoes, cut them off and throw them away.
  6. When the water boils, put the potatoes in and turn the heat to medium.
  7. Every five minutes, pull out a potato chunk, let it cool, and taste it to see if it’s ready. 
  8. When they are done, turn off the heat and pour the potatoes out into a colander. 
  9. Dress the potatoes with spices and olive oil (you probably want to add salt) and eat with your favorite no-calorie sauces and vinegars.

Appendix B: Chris Voigt

The earliest example of an all-potato diet we’re aware of is a guy named Chris Voigt

Chris was the Executive Director of the Washington State Potatoes Commission, and he was tired of hearing all the myths about potatoes being unhealthy. He wanted to remind people about the amazing nutrients contained in this everyday vegetable. So as a demonstration of the power of potato, he decided to eat nothing but 20 potatoes a day, for 60 days straight:

Chris started his diet on October 1, 2010, and didn’t use any milk, butter or cheese toppings for mashing his potatoes. The only way he had them were fried, boiled, mashed, steamed, chipped or baked. His diet continued for 60 straight days and ended on November 29, 2010.

Also here’s an incredibly corny video if you prefer that format.

Chris wasn’t trying to lose weight. In an interview conducted years later, he said, “I was kind of hoping to be alive at the end of the 60 days… I wasn’t trying to lose weight.” He was 197 pounds at the start of his diet and he describes himself as “six foot one and a half”, so his starting BMI was about 26, just slightly overweight. He seems to have been eating a pretty healthy diet beforehand and he wasn’t seriously overweight, which is why he didn’t think he would lose weight. In fact, he based his daily potato consumption off of a calculation of how much he would need to eat to maintain his starting weight. In response to an early comment on his blog, he said, “I’m eating 20 potatoes a day because that’s how many I’ll have to eat to maintain my current weight.”

But despite his best efforts, by the end of the 60 days, he weighed 176 lbs, a loss of 21 lbs to a BMI of 23.2. His cholesterol also went from 214 to 147, and his glucose went from 104 to 94. In fact, seems like almost everything that could be measured improved: “My cholesterol went down 67 points, my blood sugar came down and all the other blood chemistry — the iron, the calcium, the protein — all of those either stayed the same or got better.” (Here’s a page where someone has compiled a bunch of these numbers.)

Chris did all this in consultation with his doctor, and he does suggest that you have to have a baseline level of health for this to be safe: 

Chris Voigt didn’t go on 20 potatoes and a diet blindly. He first carried out thorough consultations with his dietician and doctor to be sure that he could actually live on potatoes for 60 days straight. After all, you need hale and hearty kidneys for processing the excessive potassium provided by 20 potatoes every day. In addition, you should have also stored ample amounts of necessary nutrients that are lacking in potatoes, for instance vitamin A, for avoiding any harmful side effects.

Those were his results. What was the diet like? 

In the abstract, Chris describes his diet like this

Literally, I just ate potatoes and nothing else. There were a few seasonings, but no gravy, no butter, no sour cream, and just a little bit of oil for cooking. That was it.

That isn’t quite enough detail for our purposes. But older archives of Chris’s site have the blog, which gets a lot more specific. Read it for yourself for the full story, but here are some highlights, focusing on what kinds of potatoes he ate and how he prepared them:

Day 1 – So I had 5 baked red potatoes for breakfast, mashed potatoes with a little garlic seasoning for lunch, and while my family had all the fixing at the steakhouse celebrating my wife’s birthday, I had garlic mashed potatoes and an order of steak fries. The all potato diet wasn’t too bad today, but I did cringe a little when everyone had ice cream for dessert.

Day 2 –  I’m really struggling to eat enough calories. I had two baked potatoes this morning with a couple shots of Tabasco sauce, a serving of mashed potatoes sprinkled with a few BBQ potato chips for a change in texture, and another serving of mashed potatoes and 5 roasted small red potatoes. I didn’t hit the 2200 calories I was hoping for today. I didn’t realize how filling the potatoes would make me feel.

Day 4 – My wife made me 3 pounds of roasted red potatoes that were lightly coated in olive oil with some of her special seasonings. While I made two containers of russet mashed potatoes, one with chives fresh out of our garden and one with a Thai herb/pepper paste I’ve never had before. My wife tells me the paste goes a long way and be careful not to use too much.

Day 6 – I was in potato Nirvana tonight. My wife boiled a bouillon cube with potato starch to make me “psuedo gravy”. It was awesome! She smothered Yukon Gold and Purple potato slices in this gravy and baked it in the oven for an hour. Then cooked homemade yellow and purple chips with artifical sweetner and cinnamon for dessert. It was heaven for a flavor deprived husband. I would marry her all over again because of this!

Day 11 – So one thing people keep asking about is, “What about my weight?” I’ve been hesitant to talk about this because I don’t want people to think of this as a weight loss diet. It is not, and it’s not something I want people to replicate. … So let me step down from my nutrition soap box and talk about weight. I started this diet at 197 pounds. I’m six foot one and a half so according to my BMI, I was a little over weight. I should be in the 175-185 range. Right now, I’m at 189 pounds. Most of that weigh loss happened early, only because I was struggling to eat enough potatoes. I seemed full the whole time so it was hard to keep eating. But now, my weight loss has become more stable.

Day 15 – I feel good. Lot’s of energy, I’m dropping a few pounds which I needed to, and no weird side effects. And mentally, I think I’ve found my groove. Weekdays are pretty easy but weekends are a little tougher, still have desires for other foods but I think those a waning a bit as I get further into this diet.

Day 19 – So my family had potstickers last night while I had roasted red potatoes. For the potstickers, my wife made a dipping sauce that I tried on my red potato wedges. It was pretty good. The sauce was soy sauce, ginger, and some off the shelf dry asian seasoning. It was a nice change of pace. It added a flavor I haven’t had in a long time.

Day 22 – I had about a pound of hash browns this morning for breakfast, two pounds of mashed potatoes with black pepper for lunch, which means I have to eat close to 4 more pounds before bed. I’m leaning towards baked potatoes with balsamic vinegar for dinner but I’m not sure I’m ready for 4 pounds of it.

Day 24 – So here is a new one for you that my wife made up. Fake ice cream made from potatoes. She took 1/2 cup cocoa powder, 1/2 cup artificial sweetner, and a little water to make a chocolate sauce. Then mixed it with about 2 cups of “riced” potatoes and ice. Blended it and put in freezer. It was actually really good, ju…st a strange texture though. I love my wife! What a treat!

Day 26 – I brought my food for the day and stuffed it in the office fridge. Two pounds of purple mashed potatoes topped with garlic salt, 6 smalled baked red potatoes that I’ll probably put balsamic vinegar on, and about 10 oz of gnocchi made with riced potatoes and potato flour, then lightly fried. Can’t boil them because they fall apart since they don’t have the egg in them that you would normally use.

…  I drove to Spokane Sunday night and caught an early flight to Boise the next day. Must remember to prepare better! Nearly starved! I broke into a small emergency stash of instant potatoes I had with me for breakfast, had 3 small bags of …chips and 1 baked potato for lunch, and an order of fries at McD’s for dinner.

Day 28 – So here is what I had yesterday to eat. About 2 pounds of roasted red potatoes lightly seasoned and with a little olive oil, 3 pounds of purple mashed potatoes sprinkled with garlic salt, and about a pound and a half of “riced” potatoes that were fried up lightly. It was kind of like light fluffy hash browns. And a few handfuls of potato chips for a change in texture.

… think about how weird and unusual this diet is. Health professionals actually suggested I include some fries and chips prepared in healthy oils as part of my diet to make me more healthy during this diet. Doesn’t that sound so weird out loud or written in this blog? You have to remember that there is absolutely no fat in a potato, no fat in any of the seasonings or herbs I’m eating. But there are 2 fatty acids that are essential to bodily functions and are needed by your body. The healthy oils from the fries and chips are supplying me those fatty acids. Without them, I would not look or feel very good at the end of these 60 days. The take home message, you need those fatty acids to live but the reality for most people is that we eat too many of them. Live in moderation!

Day 33 – Got out of the house this morning without any seasonings for my spuds. So far, I’ve eaten 6 boiled, yellow flesh, plain potatoes. You know…I really think this is getting easier. I’m not having the intense cravings for other foods that I use to have. Maybe I’ve found my groove.

…  I thought I’d take a moment to answer a couple questions I always get from folks about the diet. One is, “Are you taking any supplements?” No. This diet is about nutrition, there are so many nutrients in potatoes that you could literally live off them for an extended period of time without any major impacts to your health. If I could take supplements, I think you could probably do this diet for a really long time! Also, I get asked about beverages. I drink mostly water, but can have things that don’t add calories or any major nutrients. I do drink some black coffee, plain black tea, or an occasional diet soda.

Day 45 – I just ate about a kilo of purple mashed potatoes for dinner tonight. But I think I added too much garlic salt. Probably shouldn’t do any major kissing tonight. 🙂

Day 50 – Just in case I’m subjected to a lie detector test at some point, I have to come clean on 3 incidents. There were 3 separate times in the previous 50 days where I was making my kids lunch, peanut butter and jelly sandwiches, and without thinking, it was more of a reflex move, I licked clean the peanut or jelly that had gotten on my fingers. Its been bugging me so I needed to share.

Day 60 – So here are most of the stats from my latest medical exam and how it compares to where I was prior to the start of the diet. Weight, started at 197, finished at 176. Cholesterol, started at borderline high of 214, finished at 147. Glucose, started at 104, dropped to 94. So improvements in each of those catagories. I don’t have a hard copy yet, will try to get that tomorrow and will post online. Me Happy!!

Day 61 – (Diet officially over) Its funny because I still have yet to eat something else besides potatoes. I’ve been a little busy this morning so I wasn’t able to pack a lunch or breakfast. But the fridge in our office still had a couple of my potato only dishes. So guess what I had for my first meal at the end of the diet. Potatoes! Hopefully that will change later today. And I bet there will still be potatoes tonight, but with something on them or with them!

… One more thing, a few new folks have joined our little community and have sent me questions about the diet. First, I took no other supplements. It literally was just potatoes, seasonings, and oil for cooking. Now there were a few things we did classify as seasonings since they didn’t really add any significant nutrients, such as Tabasco Sauce which is really just dried peppers and vinegar. Had balsalmic vinegar a few times, and an occasional bouillon cube that was used in mashed potatoes or mixed with potato starch to form something like gravy. THe cubes were 5 calories and really only added sodium to the diet, which we consider a seasoning. 

Day 63 – A big thank you to the Washington Beef, Dairy, and Apple producers. They, along with the Washington Potato Commission, hosted a dinner at the Moses Lake Head Start facility for all the kids and their parents. We did crafts and a short nutrition workshop on the importance of eating healthy, well balanced meals. Not just 20 potatoes a day 🙂 And a big thank you to the staff for all of their work on this and the wonderful Mr. Potato Head they gave me. We had lean beef strips for our tortillas, along with roasted onions, peppers, and potatoes, and apple slices and low fat milk. I sampled everything and wanted to chow down but my doctor has advised me to ease back slowly into other foods. So I’m still eating a lot of potatoes!

On the one hand, Chris took the potato diet very seriously. He really did get almost all his calories from potatoes for about 60 days. He stuck to the plan.

On the other hand, he didn’t take it too seriously. He used cooking oil, spices, and a bunch of different seasonings. He still had coffee, tea, and the “occasional diet soda”. But this didn’t ruin the diet — he still lost weight and gained energy.

The results do seem astounding. More energy, better sleep, lower cholesterol, etc. etc. And how was it subjectively? “I’m really struggling to eat enough calories. … I didn’t realize how filling the potatoes would make me feel. … I feel good.” 

The weight loss results aren’t that extreme, but Chris wasn’t very overweight to begin with. He went from a BMI of 26 to an “ideal” BMI of 23. He didn’t really have many more excess pounds to lose. So let’s take a look at a more extreme example. 

Appendix C: Andrew Taylor

Andrew Taylor is an Australian man who did an all-potato diet for a full year. He started at 334 pounds and he lost 117 pounds over the course of what he called his “Spud Fit Challenge.”

Here’s a video of Andrew before the diet, describing what he is about to attempt. Here’s a video of him 11 months in. And here are some descriptions of how it went

The physical benefits of Taylor’s Spud Fit Challenge remain, he says. “I’ve maintained the weight loss and I’m still free of the daily grind of battling with food addiction. I had a check up a few weeks ago and my doctor was very happy with the state of my health.”

Taylor says that he was clinically depressed and anxious before undertaking his all-potato diet, “which is no longer an issue for me,” he says. “My mental health is much better these days.”

During his challenge, Taylor ate all kinds of potatoes, including sweet potatoes. To add flavor to his meals, he used a sprinkle of dried herbs or fat-free sweet chili or barbecue sauce. If he made mashed potatoes, he only added oil-free soy milk.

He drank mostly water, with the occasional beer thrown in (proof that no man can resist a great brew). Because his diet completely lacked meat, he supplemented with a B12 vitamin.

He also didn’t restrict the amount he consumed. Instead, Taylor ate as many potatoes as he needed to satisfy his hunger. For the first month, he didn’t work out at all and still dropped 22 pounds, but then he added 90 minutes of exercise to his routine every day.

 “I feel amazing and incredible! I’m sleeping better, I no longer have joint pain from old football injuries, I’m full of energy, I have better mental clarity and focus,” he writes on his site.

Like Chris Voigt, Andrew made sure to get regular checkups

Taylor said has had medical supervision, including regular blood tests, throughout the year. His cholesterol has improved and his blood-sugar levels, blood pressure and other health indicators are good, he explained. He feels “totally amazing,” noting he no longer has problems with clinical depression and anxiety, sleeps better, feels more energetic and is physically stronger.

Andrew is now running spudfit.com. For the specifics of Andrew’s diet, the FAQ is pretty detailed: 

A combination of all kinds of potatoes, including sweet potatoes. I used minimal dried and fresh herbs, spices and fat-free sauces (such as sweet chilli, tomato sauce or barbecue sauce) for a bit of flavour. I also use some soy milk (no added oil) when I make mashed potatoes.

I drank only water and the occasional beer. I didn’t drink any tea or coffee but I’ve never liked them anyway. If you want to drink tea or coffee I think that would be fine as long as you use a low fat (no added oil) plant based milk.

For the first month I did no exercise and still lost 10kgs. After that I tried to do around 90 minutes of training every day. I DID NOT exercise for weight loss, I did it because for the first time in years I had excess energy to burn, enjoyed it and it made me feel good. I think that whatever the amount of exercise I did, my body adjusted my hunger levels to make sure I take in enough food. If I didn’t let myself go hungry then I was fine.

Rule 1: Do your own research and make educated decisions – don’t just do things because you saw some weird bloke on the internet doing it! Also get medical supervision to make sure everything is going well for you, especially if you are taking any medications.

Rule 2: Eat a combination of all kinds of potatoes, including sweet potatoes. I have minimal herbs, spices and fat-free sauces for a bit of flavour. I also use some soy (or other plant-based with no added oil) milk when I make mashed potatoes. Also take a B12 supplement if you plan on doing this for longer than a few months. Definitely no oil – of any kind – or anything fatty such as meats, cheeses, eggs or dairy products (even lean or low-fat versions).

Rule 3: DO NOT RESTRICT OR COUNT CALORIES. I eat as much as I like, as often as I like, I do not allow myself to go hungry if I can help it.

I used a non-stick granite pan and fry in water or salt reduced vegetable stock. When I used the oven I just put the potatoes straight on the tray. I also liked to cook potatoes in my pressure cooker and my air fryer.

I felt amazing and incredible and I still do! My sleep improved, joint pain from old football injuries went away, I gained energy and improved mental clarity and focus. Also I lost 52.3 kilograms (117 pounds) over the course of the year. By far the best part is that I no longer suffer with clinical depression and anxiety.

I tried to keep it as simple as possible. I didn’t own an air fryer or a pressure cooker or any other special gadgets. Most of what I ate was either boiled, baked or mashed potatoes. I would make a really big batch of one type and then eat it for a day or two until it was gone and then repeat.

(did you eat the skins?) I did but if you don’t want to that’s ok too.

This is the most surprising thing of all, I can’t explain why but I’m not at all bored of my potato meals.

Over the month of January, following the completion of my Spud Fit Challenge, I lost another 2kg (4lbs). This took my total weight loss to 55kg (121lbs) and meant I weighed the same as I did when I was 15 years old – 96kg (211lbs)! Since then I’ve stopped weighing myself so I can’t be sure of what I actually weigh, my new clothes still all fit though and I still feel good so I guess my weight is around the same (nearly 15 months later at the time of writing this).

This diet looks pretty similar to what Chris did. All potatoes but not wildly strict — he would have seasonings and sauces and even an occasional beer. The big difference is that Andrew studiously avoided added oils, and took a B12 supplement. 

The B12 seems like a good addition to us, especially since Andrew was doing this for a full year, because potatoes contain almost no B12. Hard to say if avoiding oil was important but using oil didn’t keep Chris Voigt from seeing a lot of benefits from potatoes. On the other hand, Andrew didn’t seem to miss it. 

Appendix D: Penn Jillette 

Penn Jillette, of the famous magician duo Penn & Teller, lost over 100 lbs, down from “probably over 340”, on a diet that started with a 2-week period of nothing but potatoes.

You can hear him describe his process in this video, but here are a few choice details: 

I didn’t mind not being energetic and stuff. But I started having blood pressure that was stupid high like, you know, like English voltage, like 220 even on blood pressure medicine.

If you take medical advice from a Las Vegas magician you are an idiot who deserves to die. You have to do this for yourself and with your proper medical professionals.

And one of the really good ways to do that that worked tremendously for me is what’s called the mono diet which is just what you think from the root, eating the exact same thing.

And I could have chosen anything. I could have chosen corn or beans or whatever. Not hot fudge but anything. And I chose potatoes because it’s a funny thing and a funny word.

For two weeks I ate potatoes, complete potatoes – skin and everything and nothing added, nothing subtracted. When I say nothing subtracted I mean no skin taken off but also no water. You can’t cut it up and make it chips in a microwave. Don’t take water out of it. 

Leave the potato completely – so that means baked or boiled and not at any mealtime. You don’t get up in the morning, eat a potato. You don’t eat it at lunch or dinner. Mealtimes are obliterated. When you really need to eat, eat a potato. And over that first two weeks I lost I believe 14 pounds. So already I’m a different person.

Then after that two weeks I went to, you know, bean stew and tomatoes and salads. But still no fruit and no nuts. Certainly no animal products. And I lost an average – these words are careful – an average of 0.9 pounds a day.  So I took off pretty much all the weight in three or four months, in a season, in a winter.

And that was 17 months ago. So I’ve kept the weight off for 17 months. Now two years is magic. Very few people keep it off for two years. I’ve got seven more months to go. I think I have a shot at it.

I feel better. I’m happier. I’m off most of my blood pressure meds. Not all of them, it takes a while for the vascular system to catch up with the weight loss. I have more fun. I believe I’m kinder.

All of that having been said now that I’m at target weight I also – this is important – I also didn’t exercise while I was losing the weight. Exercising is body building. It’s a different thing. Wait until you hit the target weight, then you exercise. Then it’s easy. Then it really does good. But while you’re losing weight make it winter. Sleep a little more. Get sluggish. Let your body just eat the fat that you’ve stored up just the way you should. Hibernate a little bit. Let it eat the fat. Be a little bit like a bear.

Again, a pretty impressive story. And, as of 2019, he seems to be keeping it off.  

Appendix E: Brian & Jessica Krock

Penn’s example inspired a similar attempt from the Krocks, a couple who have jointly lost over 220 lbs starting with two weeks of an all-potato diet

He was 35 when we started this journey and tipped the scales at 514 pounds. My own weight was approaching 300 pounds and my health was starting to suffer. High blood pressure, anxiety and acne were just the start of my issues. 

We picked a start date on the calendar (June 22, 2018 – which also happened to be the 11th anniversary of when we first started dating) and started doing research. The first book I read was Penn Jillette’s Presto!: How I Made Over 100 Pounds Disappear and Other Magical Tales. It was exactly what I needed to get into the right frame of mind for starting this journey. It wasn’t a book from a doctor or a nutritionist or someone telling me why eating the way I did was going to kill me. It was a book from someone who KNEW the real struggle we have dealt with for years. Someone who spend years overweight, LOVED food, and didn’t buy into the whole “eat in moderation” philosophy a lot of our past failed diets relied on.

The first day of potatoes sucked. I seriously contemplated quitting during the FIRST day. After eating my first round of potatoes, I literally walked from our apartment to a grocery store to look at the extra cheesy hot-and-ready pizza I thought I needed. I gazed at the pizza and walked around the store looking for something to eat. Luckily, I was able to keep it together and walk out of the store and back home to my pantry full of potatoes.

I’m not trying to be dramatic, but it was seriously one of the hardest things I’ve done in my life. It took more will power than I thought either of us had.

Even when we started the two weeks of potatoes, we still weren’t sure what the heck we were supposed to do after that. We knew it was vegan. We knew we wouldn’t be able to use added salt, sugar, oil, etc. But that was about it. So we did a lot of research during those two weeks of eating nothing but potatoes. From what I could tell, after the two weeks of potatoes, Penn Jillette followed a whole food, plant-based diet for the most part, so we decided to stick with that.

 We will never go back to eating the way we used to eat. As hokey as it might sound: This is not a diet – it is a lifestyle. We know if we go back to our old ways, we’ll gain the weight back again. The best part is… we don’t want to go back to how we ate before! We actually enjoy food more now than we did before. We have a better relationship with food. We feel like we eat MORE variety now. Eating a whole food, plant-based diet has opened our minds and palates to a new world of food that we would not have given a second thought to before.

They seem to have had a harder time than the other examples we looked at. But we also notice they are the heaviest people we’ve looked at so far, so it’s not hard to imagine that it might have been roughest for them. But even so, it seems to have worked. 

As far as we can tell, they are following Penn’s approach over what Chris and Andrew did — no oil or nothin’, just potatoes. Our sense is that this is probably more hardcore than what is necessary but like, more power to them. On the other hand, this may be part of what made it so difficult. Even Andrew used seasonings! Detailed instructions for how they prepare Taters appear in their videos.

The Krocks are still making videos, and if you look at their channel, they seem to have kept a lot of weight off.

Appendix F: Potato Hack

We are also going to talk about potato hack. This is not a case study per se but it is another all-potato approach, and one that has lots of very positive reviews on Amazon, for whatever that’s worth.

Per the website, “The Potato Hack (aka The Potato Diet) is an extremely effective method for losing weight without experiencing hunger.”

The Potato Hack Overview has this to say about the details: 

Red and yellow potatoes work the best, because after they are boiled they keep longer than Russet potatoes, which tend to get mushy quicker. However, Russet potatoes do work. Try all potato types.

Sweet potatoes are not potatoes. They can work for some people, but not nearly as well. If you can not handle nightshades, purple yams with white flesh can be a substitute. Weight loss is likely to be slower when you don’t use regular potatoes.

The only way to make the potato fattening is to process it and cook it in oil. So avoid fries and chips. For the potato hack to work the potatoes need to be cooked only in water. Boil, steam, or pressure cook.

When cooked potatoes are cooled overnight in the refrigerator they develop something called resistant starch. Resistant starch is beneficial to our gut flora, balances blood sugar, and other additional health benefits. These resistant starches are not digested in the same manner as regular calories, so they have the effect of reducing the calories of potatoes.

Refrigerating cooked potatoes overnight will reduce the calories by about 17%. The potatoes can be reheated before eating without losing any of the resistant starch.

The potato hack will still work if you don’t refrigerate the potatoes, so although this step is encouraged, it is optional.

Eat the potatoes plain. Salt if you must. You can add a splash of malt or red wine vinegar if a blood sugar spike is a concern, although cooling the potatoes will reduce the glycemic response.

To get the full benefit of the potato hack, it is strongly advised to eat the potatoes plain. You are teaching your brain how to get full without flavor. This is the opposite approach taken in dieting where one continues to get flavorful food but in a restrictive manner.

With the potato diet, do not walk away from the table hungry. Eat until full.

This is a little more finicky (what potatoes to use, how to store them, etc.) but overall looks a lot like the other examples we’ve considered. 

The hack also links to some testimonies, including this one guy’s particular approach. We’ll include it here because it gives an unusual amount of detail about purchasing and preparation:  

If your time is valuable to purchase organic, because you will not need to peel the potatoes, plus they have more nutrition. If you want to save money, purchase non-organic. I cycle between both options.

The three most common options for potatoes are going to be red, yellow, and russet. 98% of the time I will purchase red or yellow. They hold up much better structurally when you take them in and out of the refrigerator over a day or two.

Russet potatoes get mushy quickly. The only time I get Russet is if I get a really good price and I know I’m doing a strict potato hack, so I’m not using those potatoes two days later.

I’ve boiled so many potatoes in the last two years, my hands have developed muscle memory as if I were driving a manual car. Here is how I’ve optimized my potato preparation.

1. Peel directly into colander if the potatoes are not organic.

2. Place the potato directly into the cleaned and dried storage container.

3. Fill the storage container. When I first started hacking, I would weigh the potatoes. Once I figured out my container could hold 5.5 pounds, then I put my scale away.

4. Remove each potato. If it is small, place it in a stockpot, otherwise chop it into parts. For me, a medium potato is 2 or 3 parts. A large potato will be more. My goal is to have approximately equal size potato parts. I want them to boil at the same rate.

5. Once that is complete, I rinse the potatoes in the stockpot.

6. Refill stockpot with clean water and boil.

7. While the potatoes are boiling, empty peels in a compost bin.

8. Boil until done to your liking. I tend to cook mine a little longer than Tim Steele describes in his book The Potato Hack, but whatever you like is the right answer. Experiment.

9. Drain and let potatoes cool. The reason I want the potatoes to cool is that if I don’t, the steam will collect on the roof of the storage container and drain down onto the potatoes, making them mushy more quickly. If I want the potatoes to cool fast, I will spread them on a cookie sheet and place them outside (provided outside is cooler than inside).

10 Put the cooled potatoes in the storage bin and refrigerate.

That is my optimized path. I’m sure you’ll find your own.