Can You Lose 5kg in Three Days With This One Weird Trick?

So many of my article ideas come from social media. “You Can Lose Up To 5 Kg in 3 Days With Potatoes & Yogurt!” the headline on the shared post declared. Well, naturally that got my attention. I write a lot about my own efforts to lose weight, so both food science and food woo are a topic of interest for me. So, gritting my teeth, I clicked the link. The new page informed me that:

The main ingredient of the potato diet, as you can conclude is the potato. This diet also includes low-fat yogurt.

Potatoes will keep you full for a longer period of time and that way you will consume less calories. While you are on this diet you will need to eat only cooked potatoes and to drink yogurt but only the one with low fat.

Varieties of potatoes. From Wikimedia

Well, bonus points for being exactly what it says on the label, I guess. Let’s go right ahead and jump right into the claims of the… article? Can I dignify it with a word like “article”? The parasitic text attached to the clickbait. How’s that?

Claims One and Two

The parasitic text continues:

The feeling of satiety is achieved when the potato starch starts swelling in our stomach Remember that you need to eat only baked potatoes and not French fries. In potatoes there is a high content of fiber which will also speed up the metabolism and that will help to lose weight fast.

I may have mentioned this before, but I’m not an organic chemist or a doctor (medical or other). I’m a stockbroker. Still, this sounded… wrong. So, I spent a whole lot of time trying to figure out a good web search that would shed some light on this. And I’ll be honest: I couldn’t find anything supporting the idea that potato starch “swells” in the stomach. I did learn quite a bit about starch, though, and one of the first things I learned is that starch comes in three distinct “flavors”:

  1. Rapidly digestible starch, which “is found in high amounts in starchy foods cooked by moist heat, such as bread and potatoes.It is measured chemically as the starch, which is converted to the constituent glucose molecules in 20 min of enzyme digestion.”
  2. Slowly digestible starch, which is expected to be completely digested in the small intestine. This includes starches found in cereals, and the starches found in potatoes either before they are cooked or after they are cooled.
  3. Resistant starch, which is starch that escapes digestion in the small intestine, and which is partially digested in the large intestine before being expelled from the body.

I also learned that there is at least one study reporting cooked potatoes average between 2.5% and 4% resistant starch, and over 90% rapidly digestible starch—although this falls to around 60% rapidly digestible and 40% slowly digestible starch if you allow it to cool. Which means that, far from reducing feelings of hunger, potato starch—the bulk of the potato—will be fully digested between 20 minutes and two hours after consumption.

As far as the claim that dietary fiber will “also speed up the metabolism and that will help to lose weight fast,” I couldn’t find any actual evidence that it “speeds up the metabolism” (if there is any, please let me know). There is some evidence, though, that increasing your dietary fiber intake will help reduce weight. According to the abstract for “Increasing total fiber intake reduces risk of weight and fat gains in women,” the authors write that “[f]or each 1 g increase in total fiber consumed [over a 20 month period], weight decreased by 0.25 kg (P = 0.0061) and fat decreased by 0.25 percentage point (P = 0.0052).” So, yes, the fiber in potato would theoretically help reduce weight.

Of course, so would the dietary fiber in anything else. Potato isn’t a magic superfood fat-destroying bullet.

Claims Three and Four

100 g potato contains only 75 calories, which is less than a glass of orange juice. On the other hand, yogurt regulates the digestive system, which removes excess fluids, toxins and other harmful substances from your body.

Claim number three is easily checked. According to the USDA, the “average” potato contains 77 calories (dietary calories or kcal, to be technical) per 100 grams. I won’t quibble with their “75 calories” statement, because they can range from 69 calories per 100 grams for white potatoes to 79 calories per 100 grams for russet potatoes and because I’m not interested in picking nits. Instead, let’s give them this one and move on to claim four:

Yogurt regulates the digestive system, which removes excess fluids, toxins and other harmful substances from your body.

That, I believe, is the longest collection of non-specific woo words strung together in a sentence that I’ve personally had to type out. I mean, where do you start? The digestive system is regulated by, broadly speaking, the autonomic nervous system through a number of receptors that detect the presence of different chemicals and pressures within the alimentary canal. Nowhere could I find any description of the impact yogurt might have on that portion of the nervous system, beyond the effect that any food would have.

Oh, and then there’s the magic word “toxins.” And by “magic” I mean “gibberish.” But, to sum up, the digestive system doesn’t do much to remove toxic substances from the body. It’s actually a primary vector for toxic substances to enter the body, and then the liver and kidneys has to do the heavy lifting removing the toxic substances. Some may be excreted as solid waste through the colon, but that’s not a primary function of the digestive system.

All right, so the claims are questionable. Does it work?

I’m glad you asked. Here, I’ll sum up the diet for you:

  • On day one, you eat a boiled potato for breakfast and drink a glass of lowfat yogurt. Lunch is two boiled potatoes and one glass of yogurt, and then dinner is two glasses of yogurt.
  • On day two, you drink a glass of yogurt for breakfast. Lunch is two boiled potatoes and one glass of yogurt, and then you skip dinner.
  • On day three, you eat a boiled potato for breakfast. Lunch is one boiled potato and one glass of yogurt. Dinner is one glass of yogurt.
  • Note: If you are exercising regularly or you have some kind of health problems then this diet is not recommended for you. Remember that this diet is only three days, so do not use it for a longer period of time.

That’s it?

Yep. But, since you asked, let’s do some analysis. We’ll be generous, and assume that each potato is a large russet potato. That gives us 292 calories per potato. The size of a “glass” of yogurt is never defined in the “article,” so let’s assume we’re talking about eight ounces of low-fat plain yogurt per glass, for 143 calories. That means that you’re consuming the following:

  • Day One: 1,448 calories
  • Day Two: 870 calories
  • Day Three: 870 calories

Yeah. No kidding. There’s a thing called Basal Metabolic Rate, which is calculated in several different ways, but is the energy required to maintain your weight if all you are doing is staying alive and maintaining your weight. Here’s a link to a calculator so you can see what your BMR is. Mine, according to that calculator, is 2,656.74 calories—a figure that matches up, more or less, with what my FitBit provides. The calculator states that to maintain your weight you should then adjust your BMR based on your activity level:

  • If you are sedentary (little or no exercise): Calorie-Calculation = BMR x 1.2
  • If you are lightly active (light exercise/sports 1-3 days/week): Calorie-Calculation = BMR x 1.375
  •  If you are moderately active (moderate exercise/sports 3-5 days/week): Calorie-Calculation = BMR x 1.55
  • If you are very active (hard exercise/sports 6-7 days a week): Calorie-Calculation = BMR x 1.725
  • If you are extra active (very hard exercise/sports & physical job or 2x training): Calorie-Calculation = BMR x 1.9

The warning I quoted above states that I shouldn’t use this diet if I’m exercising, so let’s assume I will be sedentary for three days. So, to maintain my weight as I work at my desk and walk from home to car to desk and back, I should consume 3,188 calories. Over the course of three hungry days, I’ll have burned 6,376 calories. Now, a common (but possibly incorrect) rule of thumb is that you have to burn 3,500 calories more than you take in to shed a pound of fat. So I’ll be almost a full order of magnitude short of the 5 kg this diet promises that I’ll burn. (I’d have lost 1.8 pounds, and 5 kg is 11 pounds.

In other words, the diet is not only scientifically illiterate, but it also doesn’t even work as promised.

I think we knew that.

I’m sure you did. I pretty well knew it, going into this article. But that’s not the point. This is the point:

The “potato and yogurt” diet is just one example of a general class of “miracle diets” that ask you to do “one simple thing” and promise you the moon. This particular diet has the virtue of not actually trying to sell you anything—the article doesn’t even have links to online stores selling you superfood potatoes or superfood yogurt or any nonsense like that. But so many of these miracle diets will also try to hook you into purchasing pills and powders and tinctures of serpens oleum, sometimes for more than a $100 a crack, on a repeating automatic purchase. They prey on frustration and appeal to the urge to get something for nothing, and they give you only rubbish and an empty checkbook. If you’re lucky. If you’re unlucky, they give you debt and serious health issues.

If you want to lose weight, don’t fall for mass marketing schemes through direct mail or internet clickbait. The only “one simple trick” you need, unless you have genuine medical issues, is this: talk to your doctor, eat a variety of foods in moderation, and exercise.

Further Reading on Starch:

About Richard Gant

Richard Gant is a husband, a father, and a huge nerd with a deep love of science, science fiction, and fantasy. He works for a brokerage firm he won't name here in order to keep his Compliance department happy, and frequently talks to inanimate objects as if they can understand him. He also has a difficult time writing seriously about himself in the third person.
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23 Responses to Can You Lose 5kg in Three Days With This One Weird Trick?

  1. Maria says:

    I’ll stick to old fashion way clean eating , water no soda, gold old fashion exercise. Everything in moderation , but was an interesting article. Thanks for posting.

  2. 1-Ton says:

    “This particular diet has the virtue of not actually trying to sell you anything”. That is really the most surprising thing about this. No accompanying pill, or workout video? There must have been a nice big banner ad at the top of that page, I’m guessing.

  3. The Church Lady says:

    I believe in moderation ….. as long as there is enough of it.

  4. SharonH says:

    I would never be able to look at a potato again.

    Remember the cabbage soup diet? Eating only the soup, the weight would drop off. That was an easy one to see through. The soup was mainly water and cabbage with maybe some carrots thrown in. Water has no calories and cabbage is a relatively high fiber low cal food. It wasn’t the soup per se, it was not consuming anything else. It was touted as a magic diet. Of course when normal eating was resumed things returned to their pre-soup state. Then there was grapefruit…and on and on.

  5. Paul Carter Block says:

    So I took my boiled potatoes and yoghurt, added chopped leek or green onion, with fennel leaves or grated ginger root, according to caprice, et voila.
    Revolutionary diet? Not really – it’s a salad.

  6. Danny Keith James says:

    How does one ‘drink’ yoghurt? It isn’t a liquid.

  7. Lulu3601 says:

    Years ago I read that a person could starve to death eating only raw potatoes because the body cannot digest the cellulose in raw potatoes. I have no idea if this is true or not. If true, though, one could lose weight by eating raw potatoes to reduce cravings. This sounds crazy, of course and it would be no better than any fad diet, but I am curious as to whether raw potatoes are indeed indigestible and that no calories get through. (For the revord, I’m a strong skeptic and never use fad diets.)

    • SharonH says:

      No one should eat raw potatoes. They contain toxins that are destroyed by cooking.

      “Eating the potato raw may cause abdominal cramps, diarrhea, fever and an upset stomach. Two toxic chemicals (steroidal glycoalkaloids) solanine and chaconine are naturally present in potatoes and are important components of their resistance against pests and pathogens.” Nutrition Myths

    • WorkingInACopShop says:

      You can starve to death eating absolutely nothing but lean beefsteak. Eat as much as you want: eventually you die of starvation.

      True. Look it up.

      (Save yourself time: look up “protein starvation”)

  8. Maarten says:

    Hi Brian,

    I think you’re calculations are not entirely accurate. You don’t take into account the fact that you will deplete your glycogen storage, when on this diet. Every gram of glycogen binds 3 grams of water, so that will have you lose weight fast!

    Secondly, your sodium intake will drop to almost zero. This also will make you lose weight (water). For a heavy guy (and why would anyone starting a diet like this not be heavy) I really don’t think that 5kg is outside the realm of possibility.

    You’ll regain most of it just as fast as you lost it, because it’s water. But the promise was up to 5kg weight loss, not ‘FAT’.

    P.S. From 1.8 lb to 11 lb is closer to half an order of magnitude than a full order of magnitude. I think that order of magnitude is somewhat of a hyperbole in this context.

    P.P.S. Weight calculations can be made more accurately with this tool:

    • Bill says:

      It’s still a dumb idea, though.

    • Paul Carter Block says:

      Hello Maarten
      If you hope to claim the high ground over at Camp Picky, it’s best to know the name of the person you are accusing of inaccuracy.
      Richard wrote this piece – not Brian.
      Here to help.

  9. Glenn Sherman says:

    I have dieted off and on my entire adult life, all the way from 200 lbs up to 280 lbs. Every time I diet, no matter which diet I am on (soup, calorie, atkins, shakes, etc etc) I lose about 10 lbs in the first 2 days, then plateau for a few days before any more progress shows. I’m sure the 3 day potato diet would be the same. All water of course. And sure enough, once I go off the diet, I gain back that 10 lbs immediately, and get back to the original weight in a short time, and the steady weight gain proceeds from there (about 1 1/2 pounds a year for the past 50 years). Bad genes and a love of wine!

  10. Stephen says:

    Okay, I’m still poor but not as poor as I used to be. I used to only really be able to afford potatoes because they were like 2 dollars for a 10 pound bag. I’ve never been massively unhealthy levels of fat but I’ve always had a gut. When I was eating literally potatoes every day (in every way I could think to cook them) I never lost weight. But when I was 16 and went to job corps and had no choice but to eat three healthy meals a day with no snacks at all, guess what happened! Yep, I lost weight. It isn’t about finding a diet that works. Eat whatever the fuck you want, just quit shoveling ice cream down your throat every night. Oh and getting hungry during the day is fine. It doesn’t mean go buy a Snickers bar (as an example due to their ads), it means wait for your meal time. You will NOT die from being a little bit hungry. If you would then I would be dead right this minute, or I at least would surely be dead by 6 when I will eat dinner. Losing weight takes time, you don’t GET fat in three days, don’t expect to get thin in three days either. Unless you’re already thin and have some reason to get a little thinner. Then maybe 3 days might make a difference.

    I will say as a little side note that if you are hungry and don’t have money for food but can afford one of those stupidly cheap fountain drinks at the gas station or McDonalds (but if you can afford a drink at McD, you can get a cheeseburger instead which is FAR healthier and actually what your body is saying it needs) you can use soda to help you not feel so painfully hungry for a while. It’s incredibly unhealthy but I’ve had to do it before and it does help with the pain of being hungry.

    Any strange words in this comment are thanks to my phone’s Swype thing that I didn’t notice and fix.

  11. Narendra Nayak says:

    My formula is simple more exercise for your skeletal muscle and less for your jaw muscles! Works pretty well my BMI is around 21 since decades as I follow that!

  12. richard1941 says:

    Your calculations did not take into account the vibrational energy frequencies that are developed on the potato diet.

    • Narendra Nayak says:

      We Indians know the powers of vibrational frequencies very well! Mantras pronounced by Brahmins can do anything from curing psoriasis to getting you a male baby(with proper ones uttered by a sufficiently qualified Brahmin) even w virgin can conceive. I would like to remind you that the last well known case of virgin birth was due an Indian who had helped in the process.
      But remember that if the mantras are pronounced wrongly or by a lower caste person they may have the opposite effect! You may gain weight than lose!

    • LULU3601 says:

      Of course! I just KNEW they left something out!

      • Narendra Nayak says:

        It is not a special trait of Hinduism! The Koran must be recited only in Arabic! If you chant its contents in any other language the effects will be lost. Again, that should be done only by men. If women do it the vibrations may upset their reproductive system. I do not know about the bible but perhaps the Pope when he gets time off from pardoning paedophile priests could explain!

    • 1-Ton says:

      (pulls the handle on the BS alarm)

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