Gaining weight? Beware potatoes—baked, fried, or in chips


Former Executive Editor, Harvard Health

Without meaning to, you’ve gained a few pounds over the last few years. How did that happen? Certain foods, especially the humble potato, may be partly to blame.

In a fascinating study of 120,000 healthy, non-obese women and men taking part in long-term studies of diet and health, the participants gained an average of 3.3 pounds every four years over a 13-year period. When the researchers tallied up the foods that contributed most to this weight gain, potatoes topped the list—twice:

  • potato chips
  • potatoes
  • sugar-sweetened beverages
  • red meat
  • processed meats

Other contributors to weight gain included sleeping less than six hours a night or more than eight hours, drinking alcohol, and watching television. The results were just published in The New England Journal of Medicine.

The study offered some good news and tips for losing weight, too. Foods and lifestyle choices associated with losing weight included

  • yogurt
  • nuts
  • fruits
  • whole grains
  • vegetables
  • physical activity

Walter C. Willett, who chairs the Department of Nutrition at the Harvard School of Public Health, has been warning us about potatoes for years. Here’s what he says in his book, Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating. (Full disclosure: I co-authored this book.) “Nutritionists and diet books alike often call potatoes a “perfect food.” But while eating potatoes on a daily basis may be fine for lean people who exercise a lot or who do regular manual labor, for everyone else potatoes should be an occasional food consumed in modest amounts, not a daily vegetable. The venerable baked potato increases levels of blood sugar and insulin more quickly and to higher levels than an equal amount of calories from pure table sugar.” French fries do the same thing, but with an added blast of fat.

In the Healthy Eating Pyramid that Willett and his colleagues devised, they plucked potatoes from the fruits and vegetables category and put them in the “Use Sparingly” category at the very top of the pyramid.

The new study, which came from Willett’s group at the Harvard School of Public Health, corroborates the notion that we should view potatoes as a starch—and a fattening one at that—not as a vegetable.


  1. Anonymous

    Useful information. I agree that potatoes are one of the ingredients that cause weight gain and other fried foods. I suggest eating vegetables and fruits. Healthy in natural way.

  2. Ann Mitchell

    I agree with the whole fried potato issue. we have run food surveys which suggest that people would be less obese if the cut out fried foods specially french fries and potato chips.
    Thanks for the article, it’s very interesting reading and hopefully more people will start eating healthier.

  3. Anonymous

    This type of useful post is most wanted form such authentic site. Every body should take these words seriously. To be healthy and fit one must omit potato form diet. Diabetic persons should be more careful about it.

  4. Weight Loss

    Interesting post and I particularly liked the Healthy Eating Pyramid. I very rarely eat western style food now. I tend to eat mostly home cooked Chinese,Japanese and Thai dishes.. brown rice,white meats,fish and plenty of fruit and vegetables. I avoid bread, pasta and particularly potatoes, which interestingly enough don’t seem to feature much in the healthy diets of Asian countries! Perhaps that’s why we don’t see many overweight people in Asia compared to the US or Australia!

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  6. leas52

    How many pounds of potatoes are served every day in the Harvard University various cafeterias, dining halls, etc?

  7. Richard Moss

    A common perception is that the natural sugars in potatoes would prevent a sugar spike. Apparently that isn’t the case. Interesting information for those wanting to prevent hypoglycemic reactions.

    Richard Moss, PE

  8. Mark

    This is a good, common sense article. Very helpful to one who is just finding the resources about this part. It will certainly help educate me.
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  9. Keith Jones

    Although I agree with most of the dietary guidance, I just can’t understand why sleeping for less than 6 hour leads to obesity- unless th person has the fanily sized pack of potato chips open on their stomach at the time… moderation in all things is probably the solution

  10. Anonymous

    Nutrition studies such as this one, which bring fear and confusion to dieters craving to limit calories, produce just the opposite effect in one small group of non-dieters: those who suffer from inherited High Metabolism
    [URL removed by moderator]

  11. Will Kelly

    One of the problems that I find concerning potatoes is how they are usually prepared. So many people eat potato products in two specific forms, potato chips and french fries, both of which are terrible for you. Add on top of that the fact that there are so many carbs in potatoes and it doesn’t surprise me that they are a common link amongst individuals who gain weight.

    Will Kelly

  12. Riitta

    How about going to Finland to study why obesity is not an epidemic there yet their diet is pretty much built around potatoes? Boiled or baked, 5-6 times a week, in homes, schools and workplaces cafeterias. Lack of common sense seems to be running rampant along with the other epidemy, obesity. Now there’s a link for someone to study.

    • acollierdc

      I agree, the potato itself may not be the problem so much as how it is prepared and how much is eaten. Several countries built there society around the potatoe with no increase in obesity. It is a valuable vegetable when used properly. Heirloom potatoes especially contain vital nutrients and can be a great source of antioxidants.

  13. Beryl

    We all have different body types. Some people are carbohydrate sensitive, others are Protein sensitive. The idea is to find what body type you are then you will know what foods are best avoided.

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  14. WONDERFUL Post. thanks for share.. more wait..

  15. naya

    Thank you for the article. Even though I belong to the “underweight” people, I think I need to stop my bad habit. I love to eat potatoe chips. The salty and savory taste can’t stop me to take them into my mouth. I take your article as the bulb reading moment in my life.

  16. Miles Davis

    But what about us hardgainers? Most would consider a high metabolism a blessing, but for us, it’s a curse! Obviously eating chips and sugar-sweetened beverages won’t pack on muscle, but we’ve got to constantly eat the right things and maintain our hardgainer workouts if we want to put on the good, healthy pounds!

    • acollierdc

      Being a hard gainer does not mean you should eat unhealthy foods that spike insulin. Thin people can develop type 2 diabetes as well. It’s ok to be naturally thin and eat large quantities but the ratios should still be about the same as someone who is trying to lose weight, just larger portions. You still need to provide your body with nutrients not sugars.

  17. Roland Nemeth

    Thank you P.J. Skerrett for your article. We all have to keep in mind chips, potato chips are realy harmfull. I do agree that chips are one of the ingredients that cause a massive weight gain, which hard to beat later. I don`t let my 4 years old daughter to have any. I try to avoid chips. I`m from Hungary and chips is famous there too. I never realy favour chips.
    From my point of view is the best way to lose weight is with proper nutrition and exercise.There is no “magic pill” for weight loss I suppose.One of the most effective ways to pursue weight loss is to change your eating habits and lifestyle. To do this, a person should eat more fresh foods,and not chips, prepare meals from scratch instead of in a microwave or take away and exercise on a regular basis.By eating 5-6 small meals and healthy snacks a day, the body is forced to burn calories around the clock. This new eating regimen keeps your metabolism active and also prevents overeating in one sitting.The most crucial foods for weight loss are every day fruits and vegetables. Adding more of these into your meals and as snacks not only gives your body the nutrients it needs but contains natural properties that help with weight loss.

    Best Regards

    Roland Nemeth

  18. Raymond Veguilla

    Thank you for this amazing post on healthy living. (I am never eating a potato chip again) hahaha, but really thanks this is a great post thanks for sharing. I love harvard University and this is one awesome health blog!



  19. Anonymous

    Your article give more tips being healthy,thanks for sharing.

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  21. Gordon null Barnes

    Not sure that I agree on Potatoes being fattening!. On their own and baked will give you a “Resistant Starch Food ” So named as it “Resist Digestion” . Top of the list for this is the Humble Banana. Also Yams, pasta, pearl Barley, whole grain bread, navy beans, oatmeal, lentils and brown rice are some of the common resistant starch foods. eat these and You will lose weight with all that is said about diets,
    ” Your plate Size” is the important one.

  22. Allen

    I agree with T Bjorkman. However, most will not study a paper as carefully as he has. The fine points will be lost and the conclusion will be accepted. The problem is that it then becomes public policy, as it has in this case, with the restrictions on potatoes in public schools. Willett’s statement about blood sugar and insulin level is a misleading statement. The glycemic index for potatoes varies from 56 for a red potato boiled and served cold to 101 for a boiled Desiree potato. The reason for table sugar’s glycemic index of 68 is that it is half fructose, which has the problems that you properly pointed in a prior post.

  23. J. Duncan McNeill

    I agree that potatoes are one of the ingredients that cause weight gain. Isn’t it a shame they taste so nice? I have been studying weight loss for ten years and have made a remarkable discovery. Most people are aware that any food, drink or sauce that is made in a factory is loaded with additives but most people assume they are harmless. In fact, these additives are dangerous to your health and are seen as toxins by your body. This means they cause disease and also cause weight gain. My simple weight loss plan is based on superb nutrition and nothing else. When you have that, (with no toxins) your weight seemingly falls off by itself with no effort on your part. Never in the history of weight loss has there been such an easy and effortless way to shed weight that is absolutely safe. I invite you to my website for more information at htp:// Thank you for allowing me to post here.

  24. T Bjorkman

    Please look again at the data. Supplementary Table 5, in the footnotes. The gain for boiled, mashed and baked potatoes in a non-significant 0.24 lb/4 years. Even in that category, a big slab of butter or sour cream is often made part of the dish. Thus there is no evidence that potatoes are bad if you limit the amount of fat they are eaten with.

    Based on the data, your and Willet’s assertions about the dangers of potatoes cannot be substantiated. Furthermore, this misguided claim is hindering people from making simple and sensible diet changes focused on the high-impact easy-to-remember components, like fat.

    • laura loyd

      Thank you! It’s not the potato it’s what you put on it. I eat at least 5 spuds a week, baked with salsa and hummus or fried with olive oil. I am 5’8” 140 lbs size 6 at 61. Used weigh 190 when I believed that carbs were “bad”. Never ate potaoes in those days.

    • Ralph, Cleethorpes

      High blood sugar is proven to be detrimental to health, whereas high fat diets are not.

    • acollierdc

      Ralph, that is too simplistic, high refined carb diets are detrimental but complex carbohydrates are essential. Also high fat diets can cause significant harm if the fat choices are poor (omega 6 vs. omega 3).

  25. zain

    It s a useful topic for me. I have discovered that eating potatoes is one of the reasons that make me gain weight. Thanks a lot.

  26. Jude

    Since potatoes are one of the few vegetables I can eat without getting sick (radishes are another), this won’t make me change my mind about eating them. Anyway, I exercise a lot and I’m a vegetarian, so who cares?

  27. anna

    Great article and news,but I am thinking….

    This statistic survey result says NILL to me, because I have met:

    1. guy who eats chips, sweets, burgers,drinks A LOT OF ALCOHOL, and is very thin

    2. I lost weight when one period I had to eat less food because I was busy but all tht food was from vendor machines (chips and refreshsments that is), and I lost weight during that month :/

    I wonder if statistics are not that reliable?

  28. Mark Hunneyman

    This information is useful. Thank you.

  29. Nigelinspain

    The thing I found about dieting is it´s not so much that we don´t know what certain foods do to us, it´s more the fact we do know what they will do to us but we wan´t them all the same. In fact we actually crave them.

    In most cases eating a bad diet is not about lack of knowledge it´s more about lack of willpower. More of a mental thing.

    This is were I found affirmations really began to help me. Whenever I craved something is simply repeated an appropriate affirmation to drive the craving away.

    Yes, I know it sounds easy, which of course it isn´t. But it does get easier over time. I would recommend trying it.

    [URL removed by moderator]

  30. Mj

    Unlike ‘nutritionists’ and food scientists,dietitians have been advising their patients, clients, and the general public, for years, about the need to limit/account for portions of potatoes and have, in my experience, never classified them as ‘vegetables’, but, clearly, rather,as carbohydrates. It’s such a travesty that RDs had not been given (or, for that matter, taken on themselves — myself included!)a stronger voice at a time (70’s-90’s) when their expertise in translating the science of nutrition into the foods that people needed to choose in order to effect in nutritional optimum and truth for the population. Thankfully,dietitians are more assertive and influential today, but, perhaps, at the expense of the overweight/obese epidemic

  31. Marty Perlman

    A humor moment

    Nutrition studies such as this one, which bring fear and confusion to dieters craving to limit calories, produce just the opposite effect in one small group of non-dieters: those who suffer from inherited High Metabolism.

    Before the release of the potato study results, I dealt frankly with the plight of High Metabolism Individuals in a highly serious posting:

    Your High Metabolism Individual (HMI) has an internal thermostat set higher than normal. Consequently HMIers innocently burn off their calories rather than depositing them in the body’s food banks. To most people this sounds more like a blessing than a curse. “Gosh, you look healthy,” friends say to an HMIer. “You’ve got a good appetite. You don’t have to worry about gaining weight. So what’s the problem?”

    While an HMIer can eat and eat without giving second thought to a rising midriff bulge, keeping those strategic nutrient supply lines open can be a taxing full-time job. Eating is not fun; it’s a job. . .

    The definitive HMI account continues at Thinking Out Loud,

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