Lifelong vegetarians are not different in height or weight from people who became vegetarian later in life.

A large study in the United Kingdom investigated whether people who are lifelong vegetarians are more likely to be shorter or lighter in weight than people who become vegetarians as adults. More than 350 lifelong vegetarians, 11,000 people who became vegetarian at age 20 years or older, and 29,000 non-vegetarians were surveyed. There were only two lifelong vegans, and they were included with the vegetarian group. Average height, weight, and Body Mass Index (BMI) were not significantly different between lifelong vegetarians and those who became vegetarian as adults. Results were similar for men and women. There was also no significant difference in age at menarche among the groups. Non-vegetarians were heavier than vegetarians and had higher BMIs. This study suggests that the growth of lifelong vegetarians is similar to the growth of those who were not vegetarians as children and that maturation, as indicated by age at menarche, is not affected by a vegetarian diet. It also supports the findings of other studies that show that, on average, vegetarians are slimmer than non-vegetarians.

Rosell MS, Appleby PN, Key T. 2005. Height, age at menarche, body weight and body mass index in lifelong vegetarians. Public Health Nutr 8:870-75.