Eating disorders are much more common among women than men. Now, a new study may have uncovered a neurological explanation for this disparity. Researchers find that women are more likely than men to experience brain activity relating to negative body perception.
Lead author Dr. Catherine Preston, of the Department of Psychology at York University in the United Kingdom, and colleagues publish their findings in the journal Cerebral Cortex.
According to the National Eating Disorders Association (NEDA), around 30 million people in the United States have some form of eating disorder, and around 20 million of these are women.
Popular notion has long held that women are more concerned with body image than men, and previous studies have shown that women are more likely than men to have body dissatisfaction.
"Thus, this susceptibility to body dissatisfaction may be an important factor underlying the higher rates of eating disorders in women," say the authors.
When it comes to negative perceptions of physical appearance, social pressures are believed to play a key role. Since women tend to be more susceptible to such pressures, this may explain in part why eating disorders affect women more than men.
However, previous studies have shown that in some eating disorders, particularly anorexia, patients overestimate their body size - that is, they perceive themselves to be larger in size than they actually are.
"In today's Western society, concerns regarding body size and negative feelings towards one's body are all too common," says Dr. Preston. "However, little is known about the neural mechanisms underlying negative feelings towards the body and how they relate to body perception and eating-disorder pathology."
For their study, Dr. Preston and team aimed to pinpoint the brain activity that might underlie negative body perceptions.
Using virtual reality to assess the brain's response to body appearance
The team enrolled 32 healthy individuals - 16 men and 16 women - to the study. None of the participants had a history of eating disorders, and their height and weight were measured upon enrollment.
Each participant was required to wear a virtual reality headset that, when they looked down, showed them a first-person video of a "slim" or "obese" body. In other words, it looked like the body belonged to them.
In order to enhance this illusion, the researchers poked the subjects' torso with a stick, in synchronization with the video.
During this experiment, each participant had their brain activity monitored through magnetic resonance imaging (MRI).
When participants looked at their "obese" bodies, the team identified a direct link between activity in the area of the brain associated with body perception - the parietal lobe - and activity in the anterior cingulate cortex, the brain region related to the processing of subjective emotions, such as fear and anger.
What is more, the researchers found that such brain activity was more prominent in women than men, suggesting that "owning" an obese body is likely to lead to higher body dissatisfaction in women.
The researchers say their findings may help shed light on why women are more affected by eating disorders than men.
"This research is vital in revealing the link between body perception and our emotional responses regarding body satisfaction, and may help explain the neurobiological underpinnings of eating-disorder vulnerability in women."
Dr. Catherine Preston
In future research, the team plans to further investigate how emotions influence body perceptions.