Vegetarian? You’re likely lean… and shy
A large-scale German study at the Max Planck Institute for Human Cognitive and Brain Sciences in cooperation with the University Hospital Leipzig has examined almost 9000 people to see how a vegetarian lifestyle is related to body weight and personality.
It was found that the lower the proportion of animal food in a person’s diet, the lower their body mass index (BMI) and body weight. One reason for this could be the lack of heavily processed foods in most plant-based diets.
“Products that are excessively rich in fat and sugar are particularly fattening,” says Evelyn Medawar, first author of the study. “They stimulate the appetite and delay the feeling of satiety [fullness]. If you avoid animal foods, you consume fewer such products.”
In addition, vegetarian food tends to be higher in dietary fibre. This is more filling and has a positive effect on the microbiome, or the bacteria that live in your gut. People who predominantly eat a vegetarian diet may therefore absorb less energy.
Primary or secondary?
When it comes to body weight, it also seems to make a difference what type of animal products someone eats. If someone predominantly eats so-called primary animal products (eg, meat, poultry and fish), they usually have a higher BMI than someone who mostly eats secondary animal products (eggs, milk, dairy products, cheese and butter).
Medawar uses an example to illustrate what this could mean. “A person with a 1.2 point lower BMI on average either completely avoids certain animal products, such as the primary ones, and is on a vegetarian diet. Or they continue to eat meat and fish, but less often.
“Whether nutrition is ultimately the cause of lower body weight or whether other factors are responsible for it? There is no way to determine this from the data.”
Plants and personality
The researchers also discovered that a vegetarian or vegan lifestyle is also related to personality. This is especially so with one of the five major personality factors: extroversion. The study found that people with predominantly plant-based foods in their diet tend to be more introverted than those who mainly feed on animal products.
“It’s difficult to say what the reason for this is,” says Veronica Witte, who led the study. “It could be because more introverted people tend to have more restrictive eating habits. Or because their eating habits make them more socially segregated.”
Several previous studies have found a link between a predominantly plant-based diet and depression. However, this study could not find a correlation between the two.