Doug Lisle

What Doug says, topic by topic

Vitamin B12

In a 2017 webinar with John McDougall, Lisle said B12 is the deficiency a strict vegan needs to watch, and that apart from it and vitamin D, deficiencies are rare next to the problems of excess¹. In another 2017 webinar he named B12 deficiency, and the anemia it can cause, as one possible reason a person on a plant based diet feels tired².

What all the experts say about vitamin B12

Vitamin D

In the same 2017 webinar Lisle said strict vegans should make sure they get enough sunshine or another source of vitamin D³. In a 2021 interview he described lighter skin in northern peoples as an adaptation that lets in more sun to make vitamin D and avoid rickets⁴.

What all the experts say about vitamin D

Oil

Asked in 2025 about the oil debate around Forks Over Knives, Lisle said he had not looked at the heart evidence himself⁵. He said that, looked at more broadly, oil is a heavily processed food with its calories concentrated as far as they go, about 4,000 per pound⁶. A trace of oil in a bought tomato sauce he called irrelevant, while oily dressing on a salad every night raises the calorie density of the diet a lot⁷.

In 2026 he said not all oil is alike: frying is a different matter from olive oil on a salad, which he said he would not use himself since it is pure fat and works against weight loss⁸.

What all the experts say about oil

Calorie density

In a 2019 talk Lisle described two fullness signals in the gut: stretch receptors that respond to volume and nutrient receptors that count fat, sugar and protein⁹. Stretch alone cannot be relied on, he said, because a pound of lettuce fills the stomach with only about 100 calories¹⁰. He put pure carbohydrate and protein at about 1,800 calories per pound and fat at about 4,000, and said whole foods sit far lower because they are mostly fiber and water¹¹.

By 2026 he was also stressing the low end of the range. He put the diet of human ancestors at roughly 600 to 700 calories per pound¹². A strict whole plant diet of about 300 calories per pound, with no nuts, seeds or avocado, would in his view leave many people hungry much of the time, though not overweight¹³.

In 2024 he said dried starches such as tortillas can be used wisely as a way to eat more of the wet starches, rice and beans, inside them¹⁴.

What all the experts say about calorie density

Nuts, seeds and avocado

In a 2017 webinar Lisle said worry about nuts and brain health was misplaced next to the oil and animal food most people eat¹⁵. In 2024 he said that if he were trying to lose weight he would avoid nuts and seeds entirely¹⁶. He added that richer foods such as corn tortillas are not supernormal stimuli and need not set off the pleasure trap¹⁷, but that a smooth nut butter spread on bread has no match in nature¹⁸.

In 2026 he said that vegans who drop both meat and honey, which in his account supplied about half of human calories in natural history, often end up reaching for rich vegan foods instead¹⁹. He put almond butter on sprouted grain toast at about 2,400 calories per pound, more than twice the density of steak²⁰.

What all the experts say about nuts, seeds and avocado

Salt

In a 2020 video Lisle described good cooking as blending sugar, fat and salt to push flavor past natural levels²¹. He named cheese, with its milk sugar, fat and added salt, as a strong example²².

In 2026 he said a salt free diet does no harm and makes sense for people with serious kidney disease, who should spare their kidneys any added sodium²³. Otherwise he openly differs from his friend Alan Goldhamer: a grain of salt on broccoli, he said, is easily handled by the kidneys, and harm depends on dose and duration²⁴²⁵.

What all the experts say about salt

Sugar

In the 2020 video Lisle said fat and sugar rarely meet in the same mouthful in nature, except in mother’s milk²⁶, while products like candy bars pile both together, with salt, into a supernormal stimulus²⁷. He said sugar on oatmeal did not worry him, and that barbecue sauce on fried chicken was the real problem²⁸.

In 2024 he said foragers living near the equator get about 10 to 20% of their calories from honey²⁹, roughly 300 calories a day for women and 400 for men³⁰. He said he expected no serious harm from table sugar, though honey is healthier³¹, and that while a whole natural vegan diet is probably best, adding sugar to a good diet costs little³².

Asked in 2026 about diets free of sugar, oil and salt, he said “It’s no religion to me”³³. Echoing John McDougall, he said a little sugar on oatmeal is fine, and that the real target is the main parts of the diet, such as eggs and bacon at breakfast³⁴.

What all the experts say about sugar

Starches

In a 2021 Chef AJ interview Lisle said raw potatoes, rice or beans are of little use to people, and that cooked starch has been a key part of human evolution for around a million years³⁵³⁶.

In a 2023 Q&A he put rice, beans and potatoes at roughly 400 calories per pound, below the 600 to 700 he believes the ancestral human diet averaged³⁷. For that reason, he said, there is no need to worry about how much starch is on the plate: an overweight person eating nothing but those starches would lose weight³⁸.

What all the experts say about starches

Fasting

In a 2023 Q&A on intermittent fasting, Lisle said nature does not care about meal timing, and that humans long ate their main meal in the evening after hunting and gathering³⁹. He called the evidence that skipping dinner or a longer fasting window extends life sketchy⁴⁰.

What all the experts say about fasting

Fiber

In the same 2023 Q&A Lisle said excess weight comes neither from too much fat, nor protein, nor carbohydrate, but from processing that removes fiber and water, the two parts of food that carry no calories⁴¹⁴². Oil and sugar, in his account, are what remains once corn has lost its fiber and water, and each raises the calorie density of whatever it is added to⁴³.

He does not treat fiber as a rule of its own, though. In 2026 he said blending fruit for a breakfast bowl did not bother him even if it breaks up some fiber, since he is not short of it⁴⁴.

What all the experts say about fiber

Fruit

In a 2021 Chef AJ interview on raw fruit diets versus cooked starches, Lisle said the view that humans are starch eaters and the view that they are fruit eaters are each partly right and partly wrong⁴⁵. He argued that people who have lived for tens of thousands of years in places like Norway could not have lived on fruit⁴⁶, and that humans are opportunistic omnivores rather than evolved fruit eaters⁴⁷. In his account cooked starches and animal food supplied most calories, with raw fruit and vegetables added on the side⁴⁸.

In 2026 he said he is not worried about the sugar in fruit, pointing to the fructose receptor on the tongue as a sign that humans were built to eat fruit⁴⁹.

What all the experts say about fruit

Vegetables and greens

In a 2026 Q&A Lisle called salad greens the least calorie dense food a person can eat⁵⁰. Someone at a healthy weight living on them, he said, would have to cram in 8 to 10 pounds a day and still get only about 1,000 calories; the full stomach would feel like satiety without really being it⁵¹⁵². He also said humans were not built to eat plates of steamed vegetables with cashews thrown on top to even out the calories⁵³.

What all the experts say about vegetables and greens

Potatoes

In a 2023 Q&A Lisle put potatoes at about 400 calories per pound and non-starchy vegetables at about 200, so a plate of half potatoes and half asparagus averages near 300, which he described as a rapid weight loss diet⁵⁴. A plate of potatoes alone he placed close to starvation level in calorie density, so in his view the idea of gaining weight by overeating potatoes is mistaken⁵⁵.

In another 2023 Q&A he said people who claim potatoes made them gain weight usually run tests of a few days, where the scale mostly reflects water stored with glycogen⁵⁶. Body fat, he said, changes by only about an ounce a day⁵⁷.

What all the experts say about potatoes

Meat

In a 2021 Chef AJ interview Lisle said humans did not evolve as vegans or vegetarians, and that their calories came largely from cooked starches and meat⁵⁸.

By 2026 he was putting this more strongly. He said meat and honey once made up about a third of the human diet by volume, so dropping both removes a large share of what people ate⁵⁹, and that humans were not designed for diets of only 300 to 400 calories per pound with no meat or honey⁶⁰. Personally, he said, he does not miss the taste or texture of meat when he eats a big burrito of rice and beans⁶¹.

What all the experts say about meat

Carbohydrates and low-carb diets

In a 2020 Chef AJ interview Lisle described ketogenic diets as a kind of magic trick⁶². Ketosis, he said, is a state human ancestors entered mostly when ill and not eating, and it brings a lower hunger drive, which is why such diets can produce weight loss⁶³⁶⁴. Part of the quick early loss, he added, is water held with glycogen, so weight jumps back as soon as carbohydrate returns and people then blame the carbs⁶⁵⁶⁶.

In 2023 he doubted claims that a ketogenic diet treats serious mental illness. Cutting refined carbohydrate may calm blood sugar swings, he said, but a baked potato would do the same, and he saw no reason to expect keto to beat a healthy starch based diet⁶⁷⁶⁸⁶⁹.

What all the experts say about carbohydrates and low-carb diets

Coffee, tea and caffeine

In a 2024 Q&A Lisle said even a single cup of coffee disturbs brain chemistry enough for the brain to build a tolerance⁷⁰. Treating it like any drug, he said people probably lose a little with coffee, far less than with hard drugs, and that life is slightly better without it, while granting that some may judge it worth the cost⁷¹⁷².

Asked in 2025 whether caffeinated or decaf coffee raises the risk of dementia, he said he did not think anyone knows⁷³. He suspected both are mild toxins, but called it very unlikely that coffee alone would bring on Alzheimer’s⁷⁴. In his view a fine enough study would probably show caffeine adds a small share to the wear on the brain, and he doubted one plant based doctor’s view that coffee is good for you⁷⁵⁷⁶.

What all the experts say about coffee, tea and caffeine

Alcohol

Lisle has said he does not drink. In a 2025 Q&A he said he would never consider alcohol because it kills brain cells, though he granted that an occasional beer is no big deal and that people weigh such small risks differently⁷⁷⁷⁸.

In 2026 he compared his friend Alan Goldhamer’s caution to that of someone who runs an inpatient center for alcoholics⁷⁹. He said he understood that caution, but set against it another view: that most people who drink wine show no health harm from it⁸⁰.

What all the experts say about alcohol

Chocolate

In a 2024 Q&A Lisle called chocolate chips a supernormal stimulus that people get used to, with mild withdrawal when they stop⁸¹.

In 2026 he said he has never treated chocolate as off limits, and joked that he never misses the chocolate pudding served at the McDougall program⁸²⁸³. Later that year he guessed that about 19 in 20 people eating plant based can enjoy a rich dessert a few times a week, but said one should know the difference between a burrito and a chocolate cake⁸⁴. His own sign, he said, is that he has had enough of a slice of vegan chocolate cake by the time he is halfway through it⁸⁵.

What all the experts say about chocolate

Juicing and smoothies

In his 2019 TEDx talk Lisle suggested a juice fast of two or three days, for example on carrot and apple juice, as one way to rest the fat and salt receptors and recover taste sensitivity after leaving rich foods⁸⁶.

In 2026 he described his usual breakfast bowl of acai blended with banana and said its processing did not concern him, since it is still a rich source of fruit antioxidants⁸⁷. He mocked the endless hair splitting over whether apple juice on oatmeal is one notch better than sugar⁸⁸.

What all the experts say about juicing and smoothies

Weight loss

In a 2023 interview with Rip Esselstyn, Lisle said obesity is neither a moral failing nor a disease but the natural result of a diet far richer in calories than humans were built for⁸⁹. Such a diet, he said, leads people to overeat by a few hundred calories a day until their weight settles at a higher level, and he said the average American woman gains about two pounds a year between 16 and 36⁹⁰⁹¹.

In the same interview he urged caution about new weight loss drugs such as Ozempic: their long term costs and benefits are unknown, and he expected anything that removes a tenth of body weight to strain many body systems⁹²⁹³. He also argued that excess weight is a marker rather than the cause of disease, since the rich diet behind it is what makes people ill⁹⁴.

What all the experts say about weight loss

Cravings and food addiction

In his 2019 TEDx talk Lisle described animals as driven by three motives: seeking pleasure, avoiding pain and saving energy⁹⁵. Processed foods stripped of fiber and water pack more calories per bite and give a lift to the dopamine system⁹⁶. The brain then adapts to that strong stimulus, he said, so people end up with no more pleasure than before while eating far richer food, along with obesity, diabetes and heart disease⁹⁷⁹⁸.

Going back to whole foods, he said, feels wrong at first because the motivational system now pulls the other way, and taste takes several weeks to recover, a journey few people complete⁹⁹¹⁰⁰.

In a 2024 Q&A he rejected doubts that food addiction is real. Addiction, he said, is a continuum rather than a yes or no category, and overeating rich food is in his view the most widespread addiction in the United States¹⁰¹¹⁰². He said John McDougall, who doubts the label, is mainly wary of drug companies moving into the field¹⁰³.

In 2026 he stressed individual differences: people with a strong food addict streak may need a tight diet¹⁰⁴, and, as with alcohol, where he said about 5% of people cannot drink moderately, people differ in how well they can moderate rich foods¹⁰⁵.

What all the experts say about cravings and food addiction

Exercise

In a 2024 Q&A Lisle drew on Herman Pontzer’s research to argue that exercise mostly shifts calories around within a fixed daily energy budget rather than adding to it¹⁰⁶. Only a few hundred calories a day are at stake, he said: once that budget is used up, extra running burns nothing more¹⁰⁷. Whether exercise then helps with weight depends on whether hunger rises to make up for it, which he said differs from person to person¹⁰⁸.

He told of a McDougall patient whose weight loss stalled until he began walking around the block each night, and suggested exercise may help some people by resetting appetite rather than by burning calories¹⁰⁹¹¹⁰. Quoting Rip Esselstyn, he ranked diet first and exercise second for weight¹¹¹. For general health he counted exercise among the big three with diet and sleep, citing stronger bones, heart function and blood flow to the brain¹¹²¹¹³.

What all the experts say about exercise

Heart disease

Asked in 2026 whether plant based diets truly reverse heart disease, Lisle said heart disease is among the best supported benefits of such diets, as long as they are built on whole or nearly whole foods with plenty of vegetables rather than processed vegan food¹¹⁴.

He said that even someone whose arteries are badly blocked can feel huge relief once the diet is corrected, comparing it to antibiotics turning around a near fatal infection¹¹⁵. A grim prognosis at 65, in his view, need not come true¹¹⁶.

What all the experts say about heart disease

High blood pressure

In a 2023 interview with Rip Esselstyn, Lisle argued that high blood pressure does not itself cause heart disease: the diet that damages the arteries also raises blood pressure, so the two travel together¹¹⁷. In his view, lowering the reading with drugs makes a person look healthier on paper without cutting heart attack risk¹¹⁸.

He said the one kind of stroke that blood pressure does drive, bleeding in the brain, makes up only about one in ten strokes and occurs mostly at very high readings¹¹⁹¹²⁰. He therefore saw little benefit in medicating people from around 140 down, and acknowledged that this runs against what most doctors believe¹²¹.

What all the experts say about high blood pressure

Longevity and aging

In a June 2026 Q&A Lisle said he wanted to bring some humility to the health focused vegan world. In his view a typical American on a poor diet still lives into the late 70s or early 80s, so the lifespan gap is a few years rather than decades¹²²¹²³. Where diet matters most, he said, is health span, the years lost to illness, mostly through heart disease and obesity¹²⁴.

He said his thinking had changed since about 20 years earlier: he now sees the main harm in combining poor quality modern animal food with refined plant food such as white flour and seed oils¹²⁵. He believes that a reasonable amount of animal food eaten with plenty of unprocessed plant food would remove much of that loss¹²⁶.

He added that these are averages. For many people a better diet changes nothing, he said, while for Michael Greger’s grandmother, whose heart disease was reversed by diet, it added about 30 years¹²⁷¹²⁸.

What all the experts say about longevity and aging

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