Potato Diet Experiment

If you are from the low carb camp, your brow just went up. Yes, you read that right – potato diet. What on green Earth is that, you ask? Well, you probably heard of egg fast, fat fast or bacon fast – days or weeks of eating just one foodstuff. This is it – potato diet is like potato fast. My eternal curiosity got me to try this weirdest diet of all, for the whole of 3 days. I was interested to find out about it for a while, ever since I’ve read the theory behind it, many personal accounts of success, and even a lukewarm endorsement from the #1 low-carb website in the world, believe it or not.

The idea is as controversial as it sounds. Eat nothing but plain boiled potatoes. If you think it’s crazy, well, you are not alone. And yet… the thing is, you can’t really eat too much of that. We have this interesting mechanism called sensory-specific satiety. These big words mean quite simple thing, actually: it’s difficult to eat too much of a single foodstuff, be it meat, egg or potato. We feel full for this particular taste rather quickly, although we can eat something else with no problem. “Second stomach for dessert” – sounds familiar? Now imagine that this single taste is one of a plain boiled potato. No butter, no sour cream, no bacon – just potato. Think you can eat much of that? I dare you to try.

Most people feel pretty full for the day eating about 2-3 pounds. Calories wise, it’s not much; a pound of boiled potato with skin is 354 calories, so 3 pounds give you under 1200 – way below our daily energy requirements. Nutritional profile is not bad at all, with 45g of fiber and 40g of protein. Protein is on a lowish side, but we are talking just 3 days here, so it’s fine. For longer potato fasts, adding some fats is recommended; we will return to it later. What about all that starch, you ask? Well, two things about it. First, it’s quite possible that severe caloric deficit keeps your blood sugar and insulin down – that’s exactly what article at Diet Doctor (that low carb website I mentioned earlier) suggests. Second, the way I decided to cook those potatoes increases the amount of resistant starch in it (you are familiar with this highly beneficial kind of starch from The Time Machine Diet or other sources, I assume). Recently, a study appeared claiming that cooking potato in a pressure-cooker before cooling it off increases the share of resistant starch comparing to traditional methods, so I decided to deploy my Instant Pot for that purpose.

I picked specific timing for this experiment. Having guests over for a few days, we partied with few, if any, limitations. Grilled meat, some potato (generously sprinkled by bacon grease, mind you), cheese salad, beer, wine, watermelon, etc. – you got the idea. Having gained a few pounds (most from water weight of course), and having satisfied our palates in the extreme, it was a good time to switch to a bland food for a few days and see how this approach remediates the consequences of feast. So, both I and my wife set on this course.

With this, let’s go into how these 3 days went, what I found out and what conclusions I came to.

General recommendation that I gathered from various sources is to limit the potato-only fast to 3 days, and add some butter, sour cream or milk if go for a week, with further increase of fat/protein content if interested in longer periods. I don’t know how accurate or science-based these suggestions are since I was interested in a shortest variation only. Thus my cooking method came to the following:

  • cook mid-sized red potatoes with skin in a pressure-cooker (7 minutes high-pressure with natural pressure release) on a previous day;
  • put them in the fridge overnight;
  • cut to about 1-inch cubes;
  • sprinkle with spices and bake in oven at 375 F, skin on, for 10 minutes and finish under broil for 8 minutes. No fat of any kind.

Next decision is whether to add any spices. One idea is to make potato as plain as possible, to decrease the palatability and discourage eating more of it. I tried my very first portion with as little salt as possible on it, and immediately came to a conclusion that I won’t be able to make it unless I add some spices. It’s incredible how fast that sensory-specific satiety kicks in when there is nothing to make your food interesting. If you aim for as few calories as possible while feeling relatively full, by all means go for plain non-spiced potatoes. Being just a tad above my ideal weight, I didn’t strive to lose much, so we added seasoning salt, garlic powder, some rosemary and oregano. I also had freshly cut garlic scapes from my backyard, so we chewed on some of them as well. If you have a sauerkraut going, add a forkful to your meal; there are few diets this powerhouse of fermented foods wouldn’t fit into, what with low energy density and enormous health benefits. Lastly, we tried to dunk a potato in apple cider vinegar; I didn’t care much for the taste but my wife liked it.

pressure cooker potatoes roasted and easy

(Image courtesy of Hip Pressure Cooking – site full of great Instant Pot recipes)

After adding all these taste-improving ingredients, potato became bearable. It has this interesting effect that lasted all three days: you feel satiated quickly, stuff yourself with a few more pieces, then feel full for hours and hours. Low palatability has another interesting and somewhat contradictory effect, which is a bit difficult to describe, so bear with me as I try. Unlike with most other foods, you are not excited much by expectation of your next meal – when you feel hungry, you just accept the necessity to eat another portion of it and do it rather out of that necessity, without element of a pleasure. If it sounds bad to you, it shouldn’t, and this is intriguing side to it which I can’t quite explain. See, while there is no excitement or much pleasure to it, and it comes to merely satisfying your energy needs, at the same time there is some kind of a comfort side. You don’t feel deprived of something valuable – your attention simply switches from food to something else. There, I tried to put this feeling in words – not sure how well it explains this sense of “my food is unexciting but I don’t care much about that.” It’s possible that with longer variation of this diet it becomes less comfortable, but for these three days it remained so (with possible exception of the end of the last day when I really looked forward to the next day meal, different from potato). It’s equally possible that with time it becomes your routine state of mind, making this diet easier to handle.

We ate 2-3 times a day, keeping 16:8 regimen and having our meals between noon and 8 pm. We drunk a lot of water, black coffee, tea and hot water with lemon, just as we do during any other kind of fast. I didn’t test my blood sugar reaction – many others did and posted surprising results of a very low glycemic response. How does this reconcile with starches promoting blood sugar spike? I am not sure, and I doubt anyone does – or at least I haven’t been able to find definitive explanation to this phenomenon. My working hypothesis is, plain potato in relatively small quantities provokes different glycemic response than potato combined with fats and being a part of much larger meal. Hopefully someone designs a study on this some day and finds out what really happens behind the scenes. Subjectively, being fairly sensitive to the signs of heightened blood sugar since my diabetic days, I can confidently say that I detected none of those signs – no sleepiness, no heavy feeling in limbs, no lack of energy. Just the opposite in fact – water ejection was at par with usual fasting days which indicated glycogen burn.

Finally, the morning after the third day was over showed 4 1/2 pounds weight loss for both of us(!) That’s quite remarkable, and matches observations of many others who tried this diet. I have to admit, this experiment hasn’t been staged perfectly – timing the diet after several days of excess makes me question whether we would have lost similar weight by any other fast and how much we would have lost by simply returning to our usual eating pattern. My sense is, any fast, water, fat, or egg would show similar results, while returning to normal eating over the same 3 days would have us losing about half of what we gained during feast. However, combined with experience described by many others, I’d have to consider this diet an effective weight loss weapon, with obvious limitations. Let’s get to the conclusions as they stand at this point:

  • it works; if you need to lose a few pounds quickly, it’ll do;
  • unlike low carb approach which still gives you a lot of variety in your menu, for most of us this can’t be a sustainable way of eating; it’s rather a short-term dietary intervention;
  • as such it may have its place – for instance, to break through a plateau when you exhausted all other ways;
  • it’s not my number one choice by any means; I will fully concur with Diet Doctor article linked earlier when it states: “it’s probably not very enjoyable for most people long term to eat only one single thing ever, for the rest of their life. So I believe there are better ways to lose weight.”
  • it’s a nice way to save a few bucks – I mean, two of us survived for three days on $5 worth bag of potato! OK, that’s a joke, don’t economize on good nutrition please;
  • if you find yourself isolated on a small island with tubers as the only food, you will be able to survive, providing you have means of cooking them. Make sure to have your pressure-cooker with you at the time of being expelled from a pirate ship to that uninhabited island, and ask for an island with energy supply;
  • there is certainly something to the notion that I encounter in a few good books I’ve read recently – notion of our modern food being hyperpalatable, causing us to pay too much attention to it and overeat on it. It reinforces the idea to eat real food instead of engineered creations with flavor molecules added in combinations and concentrations not found in nature, thus overriding our natural defense mechanisms.

Overall though, this experiment left me with more questions than answers. It shows just how little we know about all the mechanics of our nutrition and makes me even more skeptical about keyboard warriors who fight all over the internet thinking that they know everything there is to know about best dietary practices. Some findings are counter-intuitive, specifically for those who settled on this or that rigid paradigm. They might explain how whole nations living on rice-rich diets didn’t have our plethora of diseases; is it possible that rice alone is as harmless as potato alone, and creates different effect when combined with fats, particularly inflammatory vegetable oils? Much like deep-fried french fries? It might be the case. We do know that oxidation of carbohydrates suppresses release of fat, thus fat eaten together with carbs is likely to be stored. I also found this article, stating that “There is a considerable amount of evidence to suggest that consuming starchy carbohydrates in combination with excessive dietary fat, especially saturated fat, causes an acute state of insulin resistance that may last for hours after the meal.” There is a lot of interesting science in that write-up, and even you don’t whack your way through it all, I’d encourage you to read the conclusion in the last two paragraphs.

Am I going to deploy this method in the future? As it stands now, I have had all the potato I could possibly want for the next decade. Egg fast looks much more attractive to me right now, as does bacon fast. I might change my opinion later on, and for now I am glad to state that I have another weapon in my arsenal. Also, fair warning: I don’t think I would try this while having my blood sugar in diabetic range; at the very least I would test it frequently to make sure I am not putting it in stratosphere. Individual reactions can vary, so experience of those who didn’t find much glucose spiking needs to be applied with care and not taken on blind faith.

Last thought on this that I want to share. There is such thing as metabolic flexibility. It’s our body ability to switch from one energy source to another depending on availability, seasonal and otherwise. From evolutionary point of view, such flexibility worked as a survival mechanism for us. If you don’t have any mammoth in vicinity to hunt, you should be able to survive on tubers until another herd comes around. Obviously, supermarkets and fast food establishment at every corner eliminated the need to wait for the wildlife migration, while refrigerators made seasonality non-existent. Is it possible that purposeful training metabolic flexibility benefits our health in ways we don’t fully understand yet? Intuitively, the answer is, it’s quite possible. If that’s the case, then periodic potato fast can be beneficial in more ways than just weight loss. Metabolic muscle exercise, so to speak.

P.S. After several days of normal eating, I am going to do an egg fast, mostly to get back to familiar territory. Going to cook them in bacon grease, too.

7/16/2018 update: Please read the post on updated Maintenance Mode where I describe my current regimen with all the changes and tweaks, including some thoughts on pulsatile nature of a healthy lifestyle.

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