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: 


  • 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.

74 thoughts on “Potato Diet Community Trial: Sign up Now, lol

  1. Will says:

    Regarding Vitamin A, have you looked into Grant Genereux’s theory, which basically boils down to “Vitamin A Bad”? (For instance: https://ggenereux.blog/2018/10/08/obesity-causation/)

    While he presents it a bit crankishly, it seems like his basic argument (Vitamin A accumulates in the body, excesses have a multitude of side effects, and the modern/western diet plausibly contains enough Vitamin A to become a problem if you consume it for years) seems…not trivially dismissed?


  2. I’m the guy you linked to at the end. I now use an Instant Pot to cook the potatoes. I lost 30 pounds using some variation of the potato hack and have kept the weight off for years now. Best of luck with your study. I informed The Potato Hack Hacker’s Hangout Facebook group to recruit a few volunteers.


  3. Sarah says:

    I hope some post menopausal women sign up for a try. It’s very hard to move the weight that appears after the change…
    I also have to say, that I was vegetarian for a year. Quite quickly the meat was replaced mostly by potatoes. I hated it. Didn’t lose an ounce. To this day if we eat potatoes more than three times a week I feel sick. I live in Britain now, and that is sometimes a problem. They love potatoes here. Crazy love.

    I have managed long fasts. Personally, I would think fasting would be easier than eating nothing but potatoes. I’m interested in the results of this, but even just the idea of it puts me off. Sorry.
    Good luck!


  4. Aaron Kent says:

    So does the protocol include any upper limit on added oil? It’s unclear to me how much oil Chris Voigt ended up consuming over those 20 daily potato?



  5. If the goal is fat loss, don’t use oil at all. Boil, steam, or pressure cook are the 3 best options. Air frier with a small amount of oil might work, but not as well.

    The Potato Hack works on 2 levels. First by “volumetrics”. Filling the stomach with a low-calorie food that shuts down hunger better than any other food. The second level is by resetting the brain’s connection between hunger, flavor, and calories. You teach your brain that high flavor foods are no longer required to fill full. It is the opposite of what the processed food industry does.

    I believe it is important when potato hacking to always end a meal feeling full. This leads to a decreased appetite quickly.


  6. Dan CaJacob says:

    Do you know of any populations that just happen to eat only potatoes? I know that is unlikely, but would be an interesting group to look at.


    1. Loquat says:

      Literally nothing but potatoes? You won’t find that in the wild, since as mentioned in the post there are some essential nutrients they lack. It’s one thing for a man to eat only potatoes short-term, quite another for a pregnant woman or growing child to do so long-term.

      But there certainly have been groups that relied heavily on the potato – it was a key part of the Peruvian diet ever since they domesticated it, and of course 19th-century Irish peasants were infamously dependent on it.


  7. Robert says:

    It’s too bad Lent has just ended. If this ends up working, it seems like the length of Lent is about the right span for this diet to have significant effects – actually, that would be a good way to get a lot more volunteers.


  8. Michael Eaton says:

    I think this is a worthy effort. I don’t want to say anything to discourage the research effort, but I do feel I should offer some potential context around which the results of this research should be considered:

    When we discuss obesity as a health concern, I think most of us understand that higher weight does not correlate to poorer health outcomes in a direct or linear fashion. Tall vs. short, athlete vs. sedentary, child vs. adult, there are all kinds of factors that contribute to numbers on a scale that have no bearing on the health of the person who is standing on that scale. Poorer health outcomes are largely a function of bodyfat % because excess adipose tissue has a variety of problematic effects. That could be impact on blood lipids, hormonal changes, liver disease, or simple mechanical stress on the back and lower extremities, just to name a few.

    And yet when we discuss diets with the implied purpose of improving health outcomes, suddenly all context is thrown out the window and we become narrowly focused on weight. I totally understand that weight is maybe the ONLY thing that you can hope to get reliable reporting on with a crowdsourced study of this sort. However there is a substantial difference between loss of weight and a reduction in bodyfat.

    Consider the protein content of the potato. Per the USDA link above, 100g of Russet potato has 79 calories and 2.14g of protein. Someone who consumes precisely 2000 calories of potatoes would consequently be getting 54.18 grams of protein. That’s protein RDA for adults is 0.8g per kg of body mass. So this amount of protein consumption would meet the RDA for someone who only weighs 149lbs. Likewise, potatoes are not complete sources of protein, and are considered deficient in several essential amino acids.

    The upshot is, even if the effect size is real and reproducible, it doesn’t help us to understand the degree to which the loss is targeted at adipose tissue. Optimally you’d want the diet to predominantly or even exclusively reduce bodyfat, and not lead to a loss of lean body mass especially things like cardiac muscle, bone density, etc.

    Those concerns are not hypothetical. There is evidence that the “yo-yo effect” of weight loss and weight rebound from cyclical dieting has long-lasting impacts on health and metabolism. One suspected mechanism for this is the reduction in Resting Metabolic Rate that comes from a reduction in lean body mass. As noted towards the end of A Chemical Hunger, one thing that does appear to be reliable in the long-term is the change in body composition that comes from working to add muscle rather than looking to lose weight. Those body composition changes are most effective when protein consumption is elevated as a share of total macronutrients, often substantially above RDA.

    All that said, I greatly value all the time and effort that has gone into that series and the follow-up work you’ve done.


    1. dancajacob says:

      I would suggest adding a fat (%) or fat (lbs) field to the spreadsheet. Smart scales are pretty common, especially for overweight folks like myself who are trying to lose weight. The body comp features will vary, but even a single data point at the beginning and end would give some idea if composition changes are happening and ideally significant.


      1. I like to use a tape measure. Measure the spot where you are first likely to see weight gains and losses. For me, it is the widest spot on the waist. Take 5-7 measurements a week. Throw out the high and low numbers and average the rest.

        This allows one to gain muscle and not be penalized for not losing weight.

        Scales can be fudged and even those bodyfat scales can vary based on the room temperature and how much water you’ve consumed. But the tape measure is honest. Take the measurement at the same time, such as before showering.


      2. Michael Eaton says:

        Everything I’ve read up to this point suggests that event the best consumer-grade smart scales ($200-300) are still fairly unreliable. It does make me wonder though if they are “good enough” for the aggregated data you’d use in a study? Up the sample size and maybe the noise doesn’t matter.

        For those with access to the resources, the two best ways to get your real Lean Body Mass numbers (not just bodyfat% but bone density, muscle mass, etc.) is the DEXXA scan. Outside of a medical setting, there are niche providers who cater to the athlete/bodybuilding community but even if you know where to go it’s not cheap. Some gyms/fitness clubs have medical grade versions of the smart scales you’re talking about. That’s probably the most accessible route for really accurate individual data.


    2. I already measure my blood pressure daily so I was planning to add it to the sheet, and I can add the (probably inaccurate) body fat % my scale gives me too.

      I probably should measure my waist size but for some reason doing that annoys me so I probably won’t do it consistently. Maybe I’ll try a before-and-after measurement at least.


  9. Yev says:

    I don’t see where you preregister how you are going to analyze the data.

    What are your primary and secondary outcomes? Will you look at average weight loss or median? Absolute or relative? What will you do about people who stopped early? What about those who kept going more than 4 weeks? How will you decide if the results are significant?

    Liked by 1 person

      1. Zach G says:

        I second Yev’s point. I don’t have any major takes on how the data should be analyzed, but without pre-registration it gives you guys a lot of room to come up with good-looking results and might lead to people distrusting them (ex: this is extreme, but Alexey Guzey basically dismisses all non pre-registered findings). I assume you will be sharing your data, so it might be less of an issue than it would be in a “normal paper” where readers can’t test other hypotheses.

        Like Yev says, just on the outcomes there are a bunch of things you could look at: Avg Loss, Median Loss, Avg % Loss, Median % Loss, Avg % Above “Normal weight” Lost, Median % Above “Normal weight” Lost.

        And for all of those outcomes, you could look at a specific time-point (ex. 4 weeks) or take the final time-point for each person, or something else. Also, it’s not mentioned in your piece, but I hope you plan to followup with people months later!

        And then there are a ton of potential exclusions/interactions you can look into: Only look at people with a starting BMI above X, only look at people who do it for X amount of time, exclude people who also eat food X (oil, occasional non-potato meal, etc.) or drink food X, remove people whose data look suspect (trolls or data entry error).

        It might be hard to know ahead of time what makes the most sense to look at, so another option besides pre-registration is to report EVERYTHING you tried in the end. The nice thing about pre-registration though is that it depend on the reader trusting the author to honestly report their results. Again, open data (and code) gets around this problem to some extent as well (assuming it’s easy enough to work with).

        Lastly, pre-registration doesn’t limit the things you can look at in the data analysis. It just means you have to note any non pre-registered findings you come up with. So there’s really no downside to it aside from a little extra work


  10. Ppau says:

    I don’t really have weight to lose so I’m not really motivated enough to sign up, but I’ll certainly try making regular potatomeals!

    By the way I can’t wait to find out that Soylent is actually just mashed potatoes with a few crushed B12 tablets
    It certainly should be


  11. pie_flavor says:

    I started the moment I saw the original article, and cut it two weeks later. And for the next three months, despite eating like complete shit, I passively lost weight. I don’t have a scale – I dislike knowing the numbers – but I measured it by needing to buy a belt and eventually perfectly fitting into jeans I used to not be able to close. That petered out, so I did it for another week, and immediately started seeing effects again.

    It’s incredible. Not only am I losing weight more noticeably than intermittent fasting granted, but I’m doing it with almost zero effort. No change to *normal* eating habits is required and the flavor isn’t monotonous enough for two weeks to be a significant burden.

    I should also note that one indication of the practical effects is that a few days in you start to experience a curious effect where your stomach is physically rumbling as though you haven’t eaten in a day, but you also feel full and feel sick at the thought of eating more. I suspect the latter is purely mental as the ACH series implies – your brain re-regulating when you are supposed to feel full, before your stomach has physically shrunk enough to catch up.

    A hearty PSA for those making the attempt: *come down slowly*. If you break the fast with your favorite fast food restaurant, that is coming right back up again, and with very very little nausea as warning. I suggest salads and fish for the first few days.

    (Aside: WordPress keeps eating my post.)


    1. There is quite a bit of research pointing towards the role of gut bacteria in controlling hunger and weight loss. Candidates include a handful of bacteria like Akkermansia Muciniphila, which contains proteins that reduce satiety and have a major impact on obesity and related markers (in mice and more limited studies in humans.)

      I mention this because potato starches are one of the prebiotics that are cited as possibly increasing populations of Akkermansia Muciniphila. It’s really hard to understand why the “potato hack” would have such a lasting effect after the diet is over, but a major change to gut microbiome is one explanation that would definitely fit the bill.

      Liked by 1 person

  12. Christopher says:

    I don’t have any weight to loose either currently – but I will be watching this from afar, hope you guys get some good results! I wouldn’t actually mind even living off sweet potatoes, they are delicious!


  13. Outlook says:

    I’ve read all the posts and I can’t remember if you addressed it – is it possible that instead of a contamination, we are seeing a nutrient deficiency? Maybe even a nutrient we are unaware of? If the human body is deficient in a mineral would it keep on eating regardless of calories until it hit the mineral threshold?

    That’s my theory on why a potato diet might work so well. Potatoes are dirt fruit – no matter how much someone washes them they are probably eating more minerals than usual.


      1. Outlook says:

        Thanks! Regarding it not showing up in explorer types – my imagination is that Mineral X would accumulate in the body and it would need to be out of the diet for maybe a year before effects. Explorer types also tend to starve to death, so maybe there just isn’t a potential for obesity. Lastly, astronauts probably select for people not genetically predisposed to obesity.

        Regarding elevation – is there any substance that is more common in ground water the higher in elevation you go? There could be two sources of Mineral X – drinking water and consumed vegetables. People at higher elevations get the mineral through drinking water, no one gets it through vegetables anymore.

        Not sure how to get around the occupational correlation though.


  14. I’m kind of interested in this, but I’d prefer to do a diet of potatoes with some added steamed veggies. Just seems healthier to me 🙂

    Should I still sign up, or is that too different from the suggested diet?


  15. Anonymous says:

    I like potatoes but I often want to buy in bulk and store them in a dark, room temperature pantry. But I’ve noticed they often sprout or have parts go green after just a few days.

    Of course I could peel them to get rid of sprouts and cut away the green, but this means I can’t make the easiest and most delicious type of potato, the baked potato. And due to living in suburbia it’s kind of a pain in the ass to stop by the supermarket every single day.

    Any advice on picking out potatoes at the store that are further away from going bad? Or should I just accept this and start cooking them differently?


    1. I am a fan of buying potatoes in 10-15 pound bags at restaurant supply stores. For reasons I don’t understand, they last longer than the potatoes I buy at regular grocery stores. Red and yellow will keep longer than Russett.


    2. beleester says:

      Do you store them together with onions? That can apparently speed up sprouting in potatoes. I’ve also read that storing them with apples can slow down ripening, but haven’t tried it.


  16. Going to try this. I lost 100 lbs. 10 years ago and have counted calories for 4000 days straight, even binge days, but am stuck at what feels like a set point with half regained. RMR in the toilet, but I have an indirect calorimeter to see if this has any effect.


  17. Hey, cool idea! I’m currently recovering from omicron, but give me a few days — when I’m fully recovered I’m definitely up to try this.


  18. andriajob says:

    I can totally do this for a month. Or more if I am also allowed to fast. Is this diet going to tell us something about why obesity has risen? I fell behind on your theories sometime last year. Is there a theory that ties all this together? I agree with Sarah that fasting is likely an easier strategy for women, but I’m game to try this. Before Covid, I was fasting in the first half of my monthly cycle to lose weight. In second half, carbs help to support progesterone levels for premenopausal women.
    So, can I mix this with fasting? What are you doing for omega-3s? I usually eat sardines.


  19. Anonymous says:

    Question: could some of the effects of the all-potato diet be related to the presence of solanine? Solanine is a toxin found in potato skins that can be dangerous in large doses; the symptoms of solanine poisoning include nausea and loss of appetite. I wonder if small levels of this effect could be produced by lower doses of solanine, as would be found in an all-potato diet.


    1. Anonymous says:

      (High solanine levels are mostly found in potatoes that have been stored improperly and are associated with a green color and bitter taste. But even “normal” potatoes will contain lower levels of solanine. I’m not sure if it’s enough to have any health effects, but it’s concentrated in the skin of the potato. FWIW it actually appears to have neurological effects, since it is believed to act as an acetylcholinesterase inhibitor.)


  20. Is there a time range you want people to do this study?

    I did a week long potato hack a month ago, happy to do four weeks of it with data. I’m travelling the next two weeks for time off and would be able to start in mid may.


  21. Sam says:

    I’d be interested to see if similar “low variety” diets with a slightly “better” macro balance (e.g. more protein) have a similar effect. What about a trial of “potatoes, peas, broad beans and kale”? Or a “Scottish Highlands”-style diet of “oats, kale, milk and eggs, with salmon once a week”.


    1. One of the reasons for a mono-diet such as the Potato Hack is the reduced flavor signal. Getting full on a diet low in flavor reduces our hunger levels over time. Adding foods – while increasing nutrition – will increase the flavor signal. The caloric deficit will likely be lower.

      When you exit a Potato Hack, foods that normally would have tased OK will taste much better. Listen to Penn Jillette explain his experience at minute 12 here:

      Penn went on to lose 100 pounds in 90 days and has kept it all off. I believe getting full on low flavor resets the bodyfat setpoint much better than reducing calories with more flavorful foods. I lost 30 pounds on the Potato Hack and have kept it over for 4+ years now effortlessly.


        1. It hasn’t for me. When I added regular food back, I enjoyed the flavors of whole unprocessed foods more than I did prior to the Potato Hack. I suppose if I started eating fast food, I would undo the benefits of the potatoes, but those unprocessed foods seem far less appealing to me today.


      1. It’s interesting that Penn makes the connection to fasting. The experience of getting “over the hump” does indeed sound very similar to fasting, since you stop feeling hungry at all after about 3 days of water fasting. But it’s weird that the pure potato diet would become easier after that, since you’re still consuming calories. Generally speaking, low-calorie diets are notoriously hard to stick with because there’s no “over the hump” point where you stop feeling hungry. Why would that be the case with potatoes?


        1. The specific thing I find puzzling is: why do you feel bad on days 3-4 of the potato diet, and why does that feeling go away on day 5? (Are these generally true of people on the potato diet, or is this just something Penn experienced that is peculiar to him?) The conventional explanation for this during an extended water fast is that your body transitions to ketosis, and the “feels bad” period is “keto flu”. But you’re obviously not in ketosis on the potato diet, since you’re eating a ton of carbs. So what gives?


          1. Penn’s experience was not mine. It has been years since I read his book Presto so, I don’t recall if he physically or psychologically felt awful (or both).

            I can speculate on a few reasons he felt awful.

            1- Penn was eating out all the time at the best restaurants in Vegas. Going from that lifestyle to plain potatoes was a great leap for him. I was already preparing healthy meals at home and only eating lunch at restaurants a few times a week.

            2- Penn was on multiple prescription meds and was 100+ pounds overweight. It is possible that he had an interaction on days 3 and 4. I only needs to lose 30 pounds and was on zero meds. He is also a generation older than me.

            3- If the Slime Mold theory of environmental toxins is correct, then our fat stores wouldn’t be much different than the animals we eat. Penn would have a lifetime of environmental toxins and some of those would be liberated during a potato hack. Perhaps this could have resulted in flu-like symptoms? I never felt those symptoms, but ate mostly clean my adult life.

            If I were a Boomer, on multiple meds, with 100+ pounds to lose, I’d probably just potato hack before dinner to start. Then proceed to multiple days. Penn had a medical team working with him directly before, during, and after his weight loss. Most people will be doing this on their own.

            Liked by 1 person

        2. Unlike other low-calorie diets, you eat potatoes until you feel full. You do this enough times and the brain starts reducing hunger signals. This is part of the magic of potato hacking. The brain is getting a signal of abundance (albeit with less flavor), whereas in classic dieting the brain gets signals of restriction.


          1. Right, I get that — it’s basically the proposed mechanism of the “Shangri-La diet”. What doesn’t make sense to me is the feeling especially bad on days 3 and 4 thing that Penn talked about. Have you generally observed that to be a characteristic of the potato hack (and if so, what are the specific symptoms of it?)? Or, is it something peculiar to Penn’s experience?


  22. Well I’m on my third day and it seems to be working for me. In two days I’ve lost six pounds (2.7kg) and my sleep tracker is showing my resting heart rate going down from an average of 51 to 45, the lowest I’ve ever measured. I did have a bit of nausea on the first day but that’s gone away.

    I’m making sure to add lots of salt, as potatoes are very high in potassium so I want to keep my electrolytes balanced. Mainly I’m eating a pseudo-potato salad of boiled and refrigerated white potatoes, vinegar, salt and olive oil.

    This seems like something that would be quite easy to do for 3-5 days once a month or so. And it’s certainly easier and more effective than keto, as well as long or intermittent fasting, all of which I’ve tried before.


    1. As an update, I ended up dropping the diet at the end of the day I wrote this. I was just feeling too weak and hungry by the end. Maybe I wasn’t eating enough.

      However, I am continuing with the diet in an abbreviated form. I’m eating potatoes 1-2 non-consecutive days per week, with normal eating the rest of the time. Will continue to record my results in the spreadsheet.


  23. Note to the unwary: while hot sauce, spices, and oils seem to be okay, it’s possible that ketchup derails this diet. (No idea if this is due to the tomatoes, the small amount of sugar in the ketchup, or just the fact that it’s something with a bit of bulk that isn’t potato.) I’m on day 6. I lost a little over a pound per day on days 1-4. Introduced ketchup on the evening of day 4, lost 0.8 pounds morning of day 5. Ate ketchup with meals throughout day 5, gained 1.2 pounds morning of day 6. Anecdotally, I’ve noticed that the ketchup does seem to be a bit of an appetite stimulant (possibly just because I like ketchup? lol). I’ve decided to cut out the ketchup going forward and will see if that changes anything!


  24. DogInTheVineyard says:

    Is high potassium/low sodium being considered as a possible mechanism? If I understand correctly, the huge amount of potassium is going to lead to more urine and more sodium in that urine. Certainly this is what’s responsible for the early rapid weight loss, but could it be responsible for the altered hunger as well?

    Speaking of salt… iodine? At first my worry was that people wouldn’t be getting enough iodine, but apparently potatoes are actually quite high in iodine. 20 potatoes is 1.2 mg of iodine, which is a whole lot to eat in a day. The American Thyroid Association says that 1.1 is the “daily tolerable upper limit”, and in Japan it is apparently typical to eat 1-3mg a day. Make of that what you will.


    1. I wouldn’t worry about iodine deficiency, or really any mineral deficiency. The body doesn’t need 100% rda of every mineral every day. Our iodine stores can supply the body’s needs for three months, while B12 stores can last for 2-5 years. Deficiencies occur due to long-term dietary imbalances (e.g. B12 deficiency in vegans) and not over a few days or weeks.


      1. DogInTheVineyard says:

        Yeah, at this point I’m more curious if high iodine levels are somehow related to the diet’s success. Roughly speaking

        1: potato eaters will consume a whole lot of iodine

        2: without really understanding the biology, iodine is related to the thyroid, and the thyroid is related to body weight regulation

        3: Japanese people, who are relatively resistant to obesity, also eat a whole lot of iodine

        I can’t suggest how or why eating a lot of iodine would help people lose weight, all I can do is note the smell of a possible mechanism.


  25. CptDrMoreno says:

    I would love to join up, but I don’t think I could make it work, I’m currently trying to bulk up and a potato diet, being criminally low on protein, would probably put a hard stop to that (not to mention people like Penn Jillette look like they lost a lot of muscle mass) and doing stuff like supplementing creatine and protein will probably also mess with the diet, right?


    1. Patrick Stevens says:

      I for one would be very glad for you to follow some kind of “only potatoes and fish” diet, For Science! (I likewise want a lot more protein than there is on this diet.)


  26. Taj says:

    “…people almost never spontaneously drop 20 pounds, so we don’t need a control group.”

    I’m really interested in this project, but I raised an eyebrow here. You’ve selected for diet enthusiasts, and I’d expect a big, far-from-spontaneous, “being in a trial” effect, regardless of the effectiveness of this particular diet.

    But I guess your point is that 20 lbs is way beyond the weight loss you’d expect just from doing an arbitrary fad diet for a month. Have I understood you right? Do you have a sense of what scale of effect would count as a noteworthy result?


  27. joy_void_joy says:

    “…people almost never spontaneously drop 20 pounds, so we don’t need a control group.”

    I have actually lost > 20 pounds in two different mixed episodes (I am bipolar). I linked this to something akin to anorexia (eating way less meals than usual, but not controlling what I eat. Just going on some 1-2 days without food, my appetite adjusted rapidly without much effort besides that)
    Does this fact mean I should not enrol in the study as a potential confounder? I do not expect this study to trigger any anorexia-like or bipolar-like symptoms if that’s a concern (I am vigilant on this)


    1. joy_void_joy says:

      Actually, by anorexia, I meant triggered anorexia: I forced myself not to eat and then the appetite adjusted. Not that my appetite dropped on its own.


    2. Yeah, we would actually recommend people with bipolar disorder not enroll, both because there might be interactions with medication (especially if we’re right about the lithium thing) and because the potato diet seems to sometimes trigger hypomania even in people without bipolar


      1. joy_void_joy says:

        Thanks for the answer. I was more asking under the perspective of “will this taint the data?”. I am not under medication, and I’m type 2 bipolar, so hypomania has not been a danger to me.


  28. Dear Reader says:

    I’ll probably end my trial soon. It’s been a little over 2 weeks and I haven’t seen any weight loss. Plus I got a weird rash. Could of course be coincidence, but..


  29. Hey, potato lovers! The Kindle/e-book version of my book, The Potato Hack, will be free on Amazon all next week if anybody wants to grab one. (Feel free to mention using your affiliate links!)

    Liked by 1 person

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