What vegan and vegetarian diets can and can’t tell us about eating disorders
"No thanks, I don’t eat meat.” This simple sentence can prompt very different reactions, but the question that often follows is: “Why?”
The answer may reflect concern for animals, the environment, religion or personal health. Families and healthcare professionals may also wonder whether giving up meat offers a socially acceptable way to restrict food.
Yet our new systematic review and meta-analysis found no clear overall difference in eating disorder symptoms between people following strict vegetarian or vegan diets and people who ate meat.
A systematic review uses a structured process to identify and assess the available evidence. A meta-analysis combines the numerical results of comparable studies to estimate the overall pattern.
Eating disorders can involve distressing thoughts and behaviour around food, weight or body shape. These may include severe restriction, binge eating, vomiting or excessive exercise. Removing categories of food can therefore cause concern. However, people adopt vegetarian and vegan diets for varied reasons, including animal welfare, religion, health and environmental concerns. The meaning of the restriction is important.
Our review combined 24 studies involving 25,223 people. The studies used established questionnaires to assess experiences such as restricting food, losing control while eating and distress about weight or body shape. These questionnaires measured symptoms reported by participants. They did not establish whether each person had a diagnosed eating disorder.
We applied strict definitions to the diets being compared. Vegetarians excluded meat, poultry, fish and seafood. Vegans excluded all animal-derived foods. We excluded flexitarian, pescatarian, and semi-vegetarian diets because they allow some meat or fish and may be followed for different reasons.
The individual findings were mixed. Some studies reported more symptoms among vegetarians or vegans, some reported fewer, and others found no clear difference. When we combined the results, there was no meaningful overall difference between the dietary groups.
This finding does not mean that vegetarianism or veganism can never coexist with an eating disorder. It means that the dietary label alone tells us little about a person’s psychological health.
Motivation matters
Consider two people who stop eating meat. One acts on long-held concerns about animal welfare and remains relaxed and flexible about food. The other begins cutting out an increasing number of foods because of an intense fear of gaining weight. What they eat may look similar, although their reasons and experiences differ sharply.
Only a few studies in our review examined motivation. One study of university students found that people who adopted vegetarian diets partly for weight control reported more eating disorder symptoms. However, most studies did not record why participants followed their diets, so motivation cannot yet be used as a reliable test of risk.
It can still guide a useful conversation. Qualitative research involving people with experience of eating disorders suggests asking when the dietary change began, whether it was driven by fear, whether further food rules appeared and how much flexibility the person retained.
A sudden change accompanied by weight loss, distress, secrecy or increasing restriction may deserve closer attention. A longstanding diet that reflects someone’s values, meets their nutritional needs and causes no distress presents a different picture.
The evidence has several limitations. All 24 studies were cross-sectional, meaning that they collected information at one point in time. They cannot show whether dietary change came before eating disorder symptoms or whether people who already had symptoms were more likely to become vegetarian or vegan.
The studies also provided limited information about diet quality, duration or motivation. Most were conducted in western countries, and relatively few included adolescents or older adults. Nearly seven in ten participants were women, so the findings are less certain for men and for other groups poorly represented in the research.
Measurement may also affect the results. Standard eating disorder questionnaires were developed for the wider population. Some questions may interpret deliberate food exclusion as unhealthy restraint even when it reflects ethical or religious commitments. Researchers have therefore begun developing screening questionnaires designed specifically for vegetarians and vegans. Screening tools identify people who may benefit from fuller assessment – they do not provide a diagnosis.
Concerns about disordered eating should be taken seriously, but vegetarianism or veganism should not be treated as a warning sign on its own. A more useful assessment asks why the diet was adopted, whether it has become increasingly restrictive, whether food causes fear or distress, and whether the person is receiving adequate nourishment.
Those features reveal more about possible difficulty than the absence of meat or animal products.