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Potatoes on a plant based diet: what the doctors say
Potatoes and sweet potatoes on a plant based diet: what McDougall, Esselstyn, Barnard and Novick say, where they agree and differ, with sources.
Updated . For education only, not medical advice.
Our view
The potato is the food John McDougall would keep if he could keep only one, and he says he began writing in its defense in 200212. Almost every doctor on this site treats plain white and sweet potatoes as a staple, from Caldwell Esselstyn’s heart patients to Neal Barnard, T. Colin Campbell and Peter Rogers3456.
The bad name potatoes carry comes mostly from how people eat them: as fries, chips, or buried under butter, sour cream, cheese and bacon789. Both studies that made headlines against potatoes, one on diabetes in 2006 and one on weight gain in 2011, came from questionnaires in which fries and loaded potatoes were counted along with plain ones, as Jeff Novick showed, and Hana Kahleova makes the same point about observational studies of potatoes in general101112.
We give most weight to the low-fat clinicians who have fed patients this way for decades, and on potatoes they agree: eaten plain, they are filling, low in fat and rich in nutrients131415. The real debates are narrower, about living on potatoes alone, white against sweet, the glycemic index and how to cook them, and we cover each below16171819.
Where they agree
The doctors agree that a plain potato is hard to overeat: McDougall noted in 2011 that a large one has about 150 calories, Chef AJ puts potatoes and sweet potatoes near 365 calories per pound, and Doug Lisle says a potato is roughly three quarters water132021. Alan Goldhamer reckons whole potatoes at about 500 calories a pound against some five times that for chips, and Novick reported that potatoes topped a ranking of foods by how full they make people1511.
They also agree that the toppings, not the tuber, do the damage: Barnard says the potato itself is free of cholesterol and nearly free of saturated fat until people add butter, bacon bits or cheese, and called fries and chips grease sponges in 2022822. Goldhamer uses the same image for frying, and McDougall said in a talk posted in 2024 that the fat piled on top is what makes potatoes fattening237. Denis Burkitt went further and called potatoes slimming as long as no fat is used to cook or serve them24.
On nutrients they agree the potato carries more than its reputation: Barnard says a large one beats a large egg on protein, Campbell says even a potato-only diet would meet protein needs, and McDougall calls potatoes rich enough in vitamin C to have been known as the anti-scurvy vegetable252627. Novick listed a small potato at about twice the potassium of a banana, and Burkitt praised potatoes for their potassium in a Western diet heavy in sodium2824.
They point to whole peoples who lived on these tubers: Esselstyn described Papua New Guinea highlanders thriving on 19 kinds of sweet potato, McDougall said 92 percent of their food came from sweet potato roots and leaves when he studied them, and Barnard noted that sweet potatoes were the staple of long-lived Okinawa142930. McDougall adds that the population of Ireland doubled within 40 years of the potato’s arrival31. In the modern American diet, by contrast, Rip Esselstyn and Goldhamer both say a large share of the plant calories comes as French fries or chips3233.
Where they differ
The doctors split on whether anyone should live on potatoes alone, on white against sweet potatoes, on what the glycemic index means for potatoes, and on how far cooking method and peeling matter1641819.
Potatoes alone
McDougall cited a study published in 1928 in which two young adults, a man and a woman, lived for about six months mostly on potatoes and water and thrived34. In 2021 he answered a webinar by Michael Greger that had called a potato-only diet deficient, saying he had proposed an all white or all sweet potato diet to show how complete a single food is, not as the ideal way to eat16. He argues that underground tubers supply all nutrients but B12, while grains and beans need a little fruit or vegetable for vitamin C35, and his and Mary McDougall’s Mary’s Mini diet, one starch plus a few vegetables, is meant only for a short stretch36. Chef AJ said in 2021 that eating only starch can work well for men but can be a disaster for women trying to lose weight, who in her view need vegetables with it17. Lisle warned in 2026 that a strict diet of potatoes, vegetables and fruit near 300 calories per pound can leave people hungry much of the time, though he has no objection when someone can eat enough potatoes and corn to feel satisfied3738.
White or sweet
McDougall rates sweet potatoes perhaps a little ahead of white ones, yet calls the difference theoretical, since the root vegetables are so alike3940. Barnard says white potatoes are fine for blood sugar and sweet potatoes better4, and Rogers called the sweet potato the healthiest food in the world in 202541. Kahleova notes that the observational studies class only white potatoes, not sweet ones, among unhealthy plant foods42. On the claim that white potatoes alone would lead to vitamin A shortage, McDougall said in 2021 that he searched the National Library of Medicine and found no cases tying the two43.
Blood sugar and the glycemic index
In 2010 Novick reviewed the 2006 study of 84,555 nurses that linked potatoes to type 2 diabetes, and pointed out that its questionnaire offered only baked or mashed potatoes and fries as choices10. Since most mashed and baked potatoes in America come with butter, sour cream or cheese, he argued, the risk belongs to the way they were eaten9. McDougall called the glycemic index a poor guide in 2021, noting that one table gives chocolate cake 38 and boiled potatoes 101, and cited a 2020 randomized crossover trial in healthy people in which daily non-fried potatoes did not worsen blood sugar markers1844. Barnard still prefers to soften the effect by eating potatoes with black beans4, and Kahleova makes the same pairing with bean chili12.
Cooking, skins and safety
Novick cited a table in which a boiled potato carries 17 units of the browning compounds called AGEs and a serving of fast food fries 1,522, so he favors boiling, steaming and other water-based cooking19. McDougall likewise said acrylamide cannot form when potatoes are boiled or steamed, since it needs heat above about 248 degrees Fahrenheit45. He sees no special value in eating the skins46, but advises cutting away green patches and sprouts, where the toxin solanine collects, and not eating spoiled potatoes47. The Ornish program site adds that potatoes cooked and then cooled, as in potato salad, hold more resistant starch than a hot baked potato48.
Pesticides and peeling
In 2021 McDougall guessed that peeling removes much of the pesticide on potatoes, since sprays land on the surface, and said the answer is to stop spraying them rather than to fear eating them49. Novick argued in 2010 that the Dirty Dozen ranking leaves out the amount of each food people actually eat, so someone eating far more potatoes than strawberries may take in more residue from the potatoes despite their lower rank50.
What each expert says
JMJohn McDougall
McDougall calls himself the potato doctor and says that if he could eat one food for the rest of his life it would be potatoes1. In 2011 he defended them against a New England Journal of Medicine paper that had blamed them for weight gain, and in 2021 he answered critics who doubted potato-only diets and potatoes’ effect on blood sugar131618. He judges white and sweet potatoes too similar to rank seriously40.
Esselstyn names white and sweet potatoes as part of what his heart patients eat3. He often cites the Papua New Guinea highlanders, heavy smokers with clean arteries who lived on sweet potatoes14, and Novick reported in 2013 that he keeps potatoes on the menu even for people trying to lose weight51.
Campbell uses the potato to show how easily plants meet protein needs, saying in 2017 and again in 2020 that even a potato-only diet would supply enough, though he was not proposing one2652. In 2014 he saw no problem with potatoes within his high-carbohydrate way of eating, and by 2023 he simply called them great535.
Barnard defends the potato as a lean, cholesterol-free food spoiled by fatty toppings and frying822. For blood sugar he ranks sweet potatoes above white and suggests eating potatoes with beans4, and he points out that a big potato outdoes a big egg on protein25.
The Ornish program site lists potatoes among the sources of resistant starch, which feeds gut bacteria48. It notes that cooling cooked potatoes raises the amount, as in potato salad compared with a baked potato48.
Goldhamer uses the potato to explain calorie density: plain, it fills the stomach at about 500 calories a pound, while chips pack around five times as much and, in his view, excite the brain far more15. He adds that salt makes people eat more potato before they feel full54, and that frying turns a healthy potato into a sponge for grease23.
Rogers counts potatoes among the best foods, calling them in 2024 about as nutritionally complete as any food, with only 1 percent of calories from fat6. In 2025 he ranked the sweet potato as the healthiest food on earth, adding that potatoes need nothing more than boiling41.
Novick has answered the main studies against potatoes, the 2006 diabetes study in 2010 and the 2011 Harvard weight analysis the same year, arguing that both mostly measured fries and fatty toppings1011. He favors gentle, water-based cooking to keep browning compounds low19, and in 2007 objected to blanket advice to avoid potatoes for potassium when meat and dairy carry as much28.
Rip Esselstyn said in 2022 that about half of the small share of American calories that comes from plants is French fries32. He uses that figure to explain why so few people get enough fiber from whole plant foods32.
Chef AJ ranks potatoes and sweet potatoes at about 365 calories per pound, among the least dense starches20. She says an all-potato diet is probably harmless with some vitamin C, but advises women who want to lose weight to eat a pound of vegetables at each meal rather than starch alone17. In 2017 she showed that five-pound bags of potatoes cost under two dollars55.
Pritikin told McDougall in a 1982 interview that potatoes were part of the simple diet he first adopted to lower his own cholesterol, along with whole grains, beans, peas, fruit and vegetables56.
Lisle explains the potato’s low calorie density by its water: at about 375 calories a pound it is mostly water with some carbohydrate and a little protein21. In 2026 he cautioned that a very low density diet of potatoes, vegetables and fruit can leave some people hungry, while accepting it for those who stay satisfied3738.
Kahleova explains that potatoes land among unhealthy plant foods in American observational studies because fries, usually eaten with burgers, are the most common form12. She sees no problem with potatoes eaten alongside beans, and notes that only white potatoes, not sweet ones, are classed that way1242.
Burkitt, interviewed by McDougall, wanted people to eat far more starch, potatoes included, and denied that starch is fattening57. He valued potatoes for their potassium and called them slimming when cooked and eaten without fat24.
Following these doctors, we eat potatoes and sweet potatoes plain or with low-fat toppings such as beans, salsa or vegetables, and boil, steam or bake them rather than fry them439197. We cut away green spots and sprouts as McDougall advises47. Anyone thinking of living on potatoes alone, or managing diabetes or kidney disease, should talk it over with their own doctor first. This page is education, not medical advice.
Each small number links to its reference below: the video at the exact second, or the page where it was said.