People suffering from the eating disorder anorexia nervosa have larger-than-normal brain size, according to a new study.

The increase in brain size was especially seen in a part of the brain called insula, which increases activity when humans taste food and also in orbitofrontal cortex- a brain region that tells humans when to stop eating.

People with anorexia nervosa have a fear of gaining weight, even when they are actually underweight. These people diet, exercise and use other means to stay thin. There is no known cause for this disorder. Experts believe genes and hormones play a vital role in the onset of this disorder. Social attitudes promoting very thin bodies are known to push people into this condition, according to Medline Plus.

According to the study, larger brain regions might be associated with the affected person's ability to starve themselves. 

Researchers from University of Colorado's School of Medicine conducted the present study and the data was obtained from 19 teenage girls who were diagnosed with anorexia nervosa and 22 girls who had no such disorders.

"While eating disorders are often triggered by the environment, there are most likely biological mechanisms that have to come together for an individual to develop an eating disorder such as anorexia nervosa," said Guido Frank, MD, assistant professor of psychiatry and neuroscience at CU School of Medicine, according to a news release. 

The brain scans of participants showed that girls with Anorexia nervosa had more matter in the left orbitofrontal, right insular, and bilateral temporal cortex  compared to girls who didn't have such disorder.

The medial orbitofrontal cortex tells us when we need to stop eating.The right insula is associated with taste and even perception, which may be the reason why anorexic people feel that they are fat.

The study is published in the American Journal of Psychiatry, 2013.

A related study from University of Cambridge had recently found that people with anorexia nervosa have high risk of having autism-like behavior.