Are vegetarians less likely to be overweight or obese? Observational studies suggest that a plant-based diet rich in high-fiber foods such as vegetables, fruits, cereals, whole grains, and legumes is inversely related to body mass index (BMI). Other studies highlight the benefits of dairy products, but it is not yet clear whether animal products are beneficial in controlling weight.
A team of researchers from Tufts University has examined the connection between excess weight and a vegetarian diet. They concluded that vegetarian diets are linked to lower rates of obesity and being overweight. Taking data from healthy women in the Swedish Mammography Cohort, they compared 960 semivegetarians, 159 lactovegetarians, and 83 vegans against 54,257 omnivores. Just over two per cent of women fell into one of the vegetarian categories. All participants provided their height and weight, and completed a food questionnaire. For the study, vegan was defined as no meat, poultry, fish, eggs, or dairy products, lactovegetarian as the same but with dairy products, and semivegetarian as the same but with dairy products, fish and eggs. The results showed that average weight, BMI, and rate of overweight and obesity were highest among omnivores. In each of the vegetarian groups, average BMI was approximately one point lower than in omnivores. Forty per cent of omnivores were overweight or obese compared with 29 per cent of semivegetarians and vegans, and 25 per cent of lactovegetarians. Further analysis showed that lactovegetarians and semivegetarians had half the risk of being overweight or obesity as omnivores, and vegans had a third of the risk. The vegetarian groups had a lower energy intake and ate less protein, more carbohydrate and more fiber than omnivores.
The researchers conclude that women who are semivegetarian, lactovegetarian, or vegan are less likely to
be obese or overweight than women who are omnivores, even if they eat some animal products. They
suggest that it would help individuals control their weight if they were given advice to consume more plant
foods and fewer animal foods, and add that future studies should examine the effects of single nutrients and
different types of vegetarian diet.