Do vegans get hungry more often? What feeding trials found about hunger

Not in the trials we found, though none here recruited people who were already vegan. Over two years, people assigned a vegan diet reported no bigger change in hunger than people on a low-fat omnivorous one. At NIH, adults ate 689 fewer calories a day on a plant-only diet than on keto, with no significant difference in hunger.

This page used to say the opposite. Its earlier version told readers that a high-fiber vegan diet doesn’t give the fullness people are used to, and that the body reads the difference as hunger. It cited nothing. Hunger does come up when people explain why they gave up, in the surveys behind our piece on why vegans quit, but the strongest feeding test available points the other way. Between April 2019 and March 2020, NIH admitted 20 adults to a metabolic ward for four weeks, two weeks on a minimally processed diet made only of plant foods and two weeks on an animal-based ketogenic one. Each day they were offered three meals and snacks at twice what they were estimated to need, and told to eat as much or as little as they liked. On the plant diet they ate 689 fewer calories a day. They ate more food by weight, about 2,140 g a day against 1,473 g, and what they ate held 0.96 calories per gram against 1.9. Their ratings showed no significant difference in hunger or fullness, and none in satisfaction or in how much more they thought they could eat. Every NIH figure on this page beyond the 689 calories and the release’s own lines comes from the version the authors posted before peer review. The published paper confirms the 689-calorie result, and NIH’s release reports the same lack of difference in hunger and fullness.

What happened over two years

The NIH diets lasted two weeks each, and the study’s lead author, Kevin Hall, said they don’t yet know whether the differences would last. The NEW Soul study ran for two years. It randomized 159 African American adults with overweight or obesity, 79% of them women, to a soul food diet that was either vegan or low-fat omnivorous, with classes and cooking demonstrations for both groups. Neither group had a calorie limit and both could eat until satisfied, though the omnivorous group was asked to keep to no more than 5 ounces of lean meat a day and two egg yolks a week. Hunger was scored with the Three-Factor Eating Questionnaire at the start and four more times up to 24 months, and at no point did the change in hunger differ between the groups. The changes on the other eating and food-acceptability questions didn’t differ either, apart from one item at 12 months, where the vegan group reported a bigger rise in satisfaction after a meal.

Read it with its limits. The analysis wasn’t powered to find differences on these questionnaires, and the authors say it may have been too small to detect them. By the trial’s diet recalls, only 41% of the vegan group were counted as following the diet at three months and 29% at two years, with many not assessed; adherence in the omnivorous group was similar, 24% at two years. The authors say the question matters partly because of a belief among consumers that plant-based diets are less satisfying. This page, until this rewrite, was part of that belief.

Meal by meal: beans, tofu and veal

Single-meal tests point the same way, each with a catch. In one, 43 young men ate three breakfasts of equal calories on separate days: veal and pork patties with mashed potato, fava bean patties with a split pea mash (high protein), or fava bean patties with a pea and potato mash (low protein). After the high-protein bean meal they were less hungry and fuller than after the meat meal, and at a meal three hours later, where they could eat as much as they liked, they ate 12% fewer calories. The authors add two caveats. The bean meal had far more fiber, which most likely played an important role, and it was rated less tasty, which they say partly affected the results. Both bean recipes also included butter, so neither was vegan, and the low-protein bean meal was as filling as the meat one.

In Prague, 60 men, two thirds of them with type 2 diabetes or obesity, ate a processed meat and cheese burger on one day and a vegan tofu burger on another, matched for calories and macronutrients. Satiety was higher after the tofu burger in every group, by 9% to 25%, though the authors note the burgers differed in saturated fat and fiber and the men knew which one they were eating. A pooled analysis of nine trials found that pulses, the family that takes in beans and lentils, gave satiety ratings after a meal that added up to 31% more over time than calorie-matched comparisons, with no significant effect on how much people ate at the next meal; its authors call their data limited by small samples.

Protein is often expected to fill people up, and the NIH authors note that the higher protein eaten on the animal diet would be expected to increase satiety. Both menus offered about the same share of protein, but people ate slightly less of it on the plant diet, 14.0% of calories against 15.5%, and the hunger ratings still didn’t differ. In a separate trial, 20 men with obesity spent two weeks each on high-protein weight-loss diets, one based on soy and one on meat, and their hunger and fullness ratings didn’t differ. Whether vegans get enough protein in the first place is its own question, and our piece on protein deficiency has the survey figures.

So why do some people say they’re hungry?

Some say so. Asked for the main reason they quit, people in Faunalytics’ survey who had given up a vegetarian or vegan diet, most of them vegetarians, mentioned hunger 18 times, next to 51 mentions of cravings and 228 of disliking or being bored with the food or wanting meat. Faunalytics’ 2023 re-analysis of that survey, which also coded answers to other questions, lists experiencing hunger among the common issues and quotes one respondent: “I was always hungry and craving for meat.”

The trials above don’t explain that person, and I’m not going to pretend they do. None of them set out to study people who were already vegan. NIH excluded volunteers who kept to particular diets, vegans among them, and the two meal tests and the two-week soy study enrolled only men. What the NIH figures do show is that people ate 550 to 700 fewer calories a day on the plant diet (NIH’s range for the two-week and final-week comparisons), on food with half the calories per gram, without reporting more hunger. Whether that holds for someone eating that way for years, the studies cited here can’t settle. NEW Soul ran for two years, but only 29% of its vegan group were counted as following the diet at the end.

What I’d do about it

If you’re hungry, eat more, and build the plate on the foods these trials used. In these tests, meals built on legumes or tofu were rated as filling as, or more filling than, the meat meals or calorie-matched foods they were compared with, though only the bean breakfast test found people ate less afterwards. A dinner on the NIH plant menu might be a baked sweet potato, chickpeas, broccoli and oranges, which is not a sad side salad. That’s the site’s advice, not a finding. No trial here told hungry vegans to do it and checked the result. The bean study’s authors note that gastrointestinal upset puts some people off legumes, and our piece on vegan gas and bloat deals with that. If the hunger comes with weight loss you didn’t intend, or with feeling unwell, take it to a doctor or a registered dietitian.

The part I’m least sure about is who stood behind those 18 mentions of hunger. A survey answer can’t say whether they were under-eating or whether something else was going on, and I’d rather leave that open than invent an explanation the way the old page did. For ideas on what goes where the meat used to be, our guide to what vegans eat instead of meat starts with the beans and the tofu.