In an interview published Oct. 8 by The Washington Post, Walter Willett, 81, Harvard professor of epidemiology and nutrition, walked readers through a typical day of eating. Widely considered the most-cited nutrition scientist in the world, with thousands of published papers to his name, Willett leads the Nurses' Health Study and co-chairs the 2025 EAT-Lancet Commission on Healthy, Sustainable and Just Food Systems. His plate, in essence, is a live demonstration of four decades of his own research.
Willett, a professor at the Harvard T.H. Chan School of Public Health, grew up on a Midwest farm milking cows and eating a meat-heavy diet. He studied food science and physics in college before earning degrees in medicine, public health and epidemiology. His decades of research overturned the 1980s–90s orthodoxy of avoiding all fat in favor of carbohydrates: he showed trans fats were tied to heart disease and stroke, helping shift U.S. dietary guidance toward a Mediterranean-style emphasis on the quality — not the quantity — of fats and carbohydrates. Trans fats were subsequently driven out of the food supply.
His breakfast never changes: steel-cut oatmeal with Greek yogurt, nuts and blueberries, plus a small glass of orange juice. He concedes the juice counts as a sugary drink, but points to evidence that blueberries protect against neurodegenerative disease and that orange juice is linked to lower rates of cognitive decline.
Lunch leans plant-based: a big salad from the school's cafeteria bar with chickpeas and tofu, or a whole-wheat peanut-butter sandwich at home, sometimes with a little jam or honey and a carrot on the side. Simple, cheap, unpretentious.
Dinner is usually fish or chicken with his wife, alongside vegetables and whole grains. Snacks are apples and carrots, and he bikes to work — exercise folded into the commute.
His rule of thumb, in his own words: "eat a variety of healthy, mostly plant-based foods, and find a way to do it that's enjoyable." In practical terms: one serving of dairy a day, one serving of other animal protein (fish or chicken), red meat no more than once a week, with plenty of whole grains, fruits, vegetables, nuts and olive oil. He has long argued the "ultra-processed" label is a distraction — sugary drinks are the key item to avoid — and that moderate animal protein fits within a Mediterranean-style pattern.
Willett also co-chaired the EAT-Lancet Commission, whose 2025 report recommended averaging just 15 grams a day — about a pound a month — of beef, pork and lamb, claiming global adoption could prevent roughly 15 million premature deaths a year. Critics argue the report ties diet to a climate agenda. The distinction matters: the 15-gram figure is the commission's population-level recommendation, not Willett's personal menu — the interview gives only frequency-level numbers for his own meals, with no gram counts for beans or grains and no egg count.
Keywords: Walter Willett, nutrition science, Mediterranean diet, EAT-Lancet, Harvard