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Vegetables on a plant based diet: what the doctors say
Vegetables and leafy greens on a plant based diet: what McDougall, Esselstyn, Barnard, Goldhamer and other doctors say, where they agree and differ.
Updated . For education only, not medical advice.
Our view
No doctor on this site argues against vegetables; the questions are how much of the plate they should take, whether to cook them and whether a salad needs added fat123. Greens matter most to Caldwell Esselstyn, who has asked his heart patients to chew a small portion of cooked leafy greens six times a day4, and Peter Rogers eats some every day and explains the same nitrate pathway Esselstyn teaches56.
We give most weight to the low-fat clinicians who have fed thousands of patients for decades, and on the size of the vegetable share they line up: non-starchy vegetables hold so few calories that they cannot carry a diet, so starches do the feeding and vegetables fill the plate around them789. Where an added fat for salads is debated, we follow the doctors who use no oil, since Jeff Nelson points out that years of very low-fat diets heavy in colorful vegetables produced no known wave of vitamin A shortage1011.
Where they agree
They agree that vegetables are the least calorie-dense food a person can eat: Novick put them at about 150 calories a pound in 1999, Goldhamer gave salad about 100 in 2025, and Rogers said greens carry roughly a tenth of the calories of starches12813. Doug Lisle drew the practical lesson in 2019: a pound of lettuce stretches the stomach while supplying only about 100 calories, so it cannot by itself keep someone full for long14.
From that follows a second point of agreement, that vegetables work as company for starches rather than as the base: McDougall in 2011 said that living on them would take bushels of broccoli daily, and Goldhamer in 2026 said it would take some 20 pounds of raw vegetables115. Lisle, looking at human history in 2021, found no people anywhere whose main calories come from raw fruit and vegetables16.
Esselstyn and Rogers describe the same mechanism for leafy greens: mouth bacteria turn their nitrate into a compound that the stomach converts to nitric oxide, which relaxes the arteries46. Both caution that fluoride mouthwash and antacid drugs can interrupt it1117. T. Colin Campbell adds a case for whole vegetables over isolated nutrients: he recalled that smokers given beta-carotene pills in large trials ended up with more lung cancer, not less18.
Where they differ
The differences are about proportions and preparation: how large a share of the diet vegetables should be, raw or cooked, and whether a salad needs fat to be absorbed19203.
How much of the plate
McDougall in 2022 put non-starchy vegetables at about a tenth of a usual diet, said people seeking faster weight loss could raise them to a quarter, and set half as the ceiling, past which he said hunger comes back19. Novick’s 2012 advice for a stalled weight loss was similar, with vegetables filling a third to a half of what the eye sees on each plate21. Chef AJ in 2021 asked her clients for at least a pound of vegetables at every meal, breakfast included, before starch22. Goldhamer in 2026 went further, saying raw fruit and vegetables can be most of the volume and perhaps 40 to 50 percent of the calories2, while Rogers said greens give him only about 5 percent of his calories5.
Raw or cooked
Esselstyn’s greens are cooked by steaming or boiling for around six minutes until tender4, and Barnard said in 2020 that people whose digestion objects to raw cabbage-family vegetables can cook them a bit longer23. Campbell said in 2023 that salads are very good but that he knows of no evidence an all-raw diet is better, and that cooking does no real harm20. Goldhamer added in 2026 that raw food diets tend to drift toward fruit, nuts and avocado because vegetables alone supply too few calories, and that some of his raw food patients developed depletion24.
Fat on the salad
Rip Esselstyn in 2022 allowed a quarter to half an avocado on a salad as a condiment25, while Lisle said in 2026 he would not pour olive oil on his own salad because it is pure fat26. Nelson in 2026 challenged the idea, which he said Michael Greger among others repeats, that a salad needs fat for its carotenoids27. He granted that adding fat lifts carotenoid levels in the blood for a few hours, but noted that one early study was paid for by Procter and Gamble to test a full-fat dressing and that the avocado industry funded later work3.
Which vegetables
Esselstyn names the leafy greens, from kale and collards to chard and bok choy28, while Barnard stresses the cabbage family, citing sulforaphane, which he said pushes the liver to produce extra detox enzymes29. Asked to pick one favorite in 2021, Barnard declined and said he rotates spinach, broccoli, Brussels sprouts and kale30. Rip Esselstyn’s PLANTSTRONG site argues for variety by color, since different colors bring different vitamins and plant compounds31.
What each expert says
JMJohn McDougall
McDougall warned in 2011 that a diet of green and yellow vegetables alone is too bulky and too low in calories, and that people who try it often get cramps and tire easily1. He wanted starches at the center and vegetables beside them for color, interest and vitamins such as A and C7. In 2022 he allowed a larger vegetable share for faster weight loss, but never more than half19.
Leafy greens are a signature of Esselstyn’s heart program, and his 2014 paper on 198 patients describes generous daily servings of them32. In a 2014 lecture he asked for a fist-sized cooked portion with balsamic vinegar six times a day, and by 2023 the portion he named had shrunk to about a quarter of a fist, still six times daily334. A talk posted in 2011 has him describing an Okinawan trial where women given extra local greens showed more of the cells that mend the artery lining34.
Campbell uses vegetables to make his case against single-nutrient pills: when beta-carotene was taken out of vegetables and given to heavy smokers, their lung cancer risk rose18. In 2023 he said salads at lunch had become his favorite meal35, while doubting that an entirely raw diet has any advantage20.
In his 2024 Power Foods talk Barnard ranked cabbage-family vegetables second and other greens third in the Harvard weight data he cited36. He said a serving of broccoli brings about 5 grams of fiber for some 55 calories, along with sulforaphane29. For sensitive stomachs he suggested cooking those vegetables a little longer23.
In a 1999 radio interview Ornish grouped vegetables with fruit, grains and beans as complex carbohydrates whose fiber slows absorption and keeps blood sugar from spiking37. Eating out in 2019, he said he asks the kitchen for its freshest vegetables cooked without oil, butter or salt38.
Goldhamer often uses salad to explain calorie density: at about 100 calories a pound, he said in 2025, living on it would take some 20 pounds a day8. In 2026 he still wanted raw fruit and vegetables to make up most of the volume on the plate, with potatoes, rice and beans supplying much of the rest2. He finds vegetables easier to eat in quantity once cooked15.
In a 2026 video Rogers told people trying to lose weight to eat their greens first, since their low calorie density fills the stomach early13. He explained the nitrate route to nitric oxide and warned that fluoride mouthwash and acid blockers interfere with it617. He eats greens daily, though they supply only a small share of his calories5.
Novick wrote in 2010 that many people who call their diet vegetable based actually get most calories from nuts, fruit or starches, because non-starchy vegetables average about 100 calories a pound9. He liked to note that a tablespoon of olive oil holds nearly the calories of a whole pound of broccoli39. In 1999 he reported a Harvard study of more than 114,000 adults, observational and without a comparison diet, in which five or six daily servings of fruit and vegetables went with a 31 percent lower risk of ischemic stroke than fewer than three40.
Nelson argued in 2026 that people eating low-fat plant diets full of carrots, sweet potatoes, squash and greens are anything but short of carotenoids27. He asked where the patients are who lost vitamin A or their sight by skipping oil on their vegetables, and said he had never seen one10.
In a 2018 talk Rip Esselstyn said the calcium the body absorbs best comes from leafy greens and beans rather than dairy41. He treats avocado on a salad as a condiment, a quarter to half at most25, and his PLANTSTRONG site encourages eating many colors of vegetables31.
Chef AJ places non-starchy vegetables at the bottom of the calorie density scale, about 100 calories a pound, as she said on a 2022 podcast42. In 2021 she replaced the half-and-half plate with a simpler rule for her clients: a pound of vegetables at each meal, then as much starch as they can manage22.
After his heart disease diagnosis, Pritikin told McDougall in 1982, he switched to whole grains, beans, peas, potatoes, fruit and vegetables43. In the same conversation he agreed that starches, vegetables and fruit make the diet that best supports health44.
Lisle explains that romaine lettuce does not excite us because it holds hardly any calories, unlike a candy bar45. In his account of human evolution, cooked starches and some animal food supplied most calories, with raw fruit and vegetables as a garnish46. He said in 2026 he would not dress his own salad with olive oil if weight loss is a goal26.
We eat vegetables and leafy greens every day, alongside the starches that carry most of the calories, as McDougall, Goldhamer and Novick describe7221. How large the vegetable share should be, raw or cooked, and whether to add fat are the points where these doctors differ, so questions about your own health belong with your own doctor. 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.