Women may be biologically wired to be more vulnerable to eating disorders, according to new research.
Experiments on female rats found they were more likely to gorge than their male counterparts - suggesting it is not just cultural pressures that are to blame.
The study is the first to establish sex differences in rates of binge eating in animals, and the researchers say it has implications for humans.
People with binge eating disorder often eat an unusually large amount of food and feel out of control during the binges.
Women are up to 10 times more likely than men to have an eating disorder.
Elton John and Princess Diana are among celebrities who suffered bulimia, while Oprah Winfrey and Janet Jackson have spoken about their battles with binge eating.
Psychologist Professor Kelly Klump, of Michigan State University, said: "Most theories of why eating disorders are so much more prevalent in females than males focus on the increased cultural and psychological pressure that girls and women face.
"But this study suggests biological factors likely contribute as well, since female rats do not experience the psychosocial pressures that humans do, such as pressures to be thin."
The research provides some of the strongest evidence yet that biology plays a role in eating disorders.
Professor Klump and colleagues ran a feeding experiment with 60 rats, half of them female, for two weeks by replacing food pellets periodically with vanilla frosting.
They found the rate of binge eating "proneness" - the tendency to consume the highest amount of frosting across all feeding tests - was up to six times higher in female as compared to male rats.
Professor Klump said the tendency to binge eat may be related to the brain's natural reward system, or the extent to which someone likes and seeks reward.
The researchers are now testing the rats to see if female brains are more sensitive and responsive to rewarding stimuli such as food high in fat and sugar, and the chemicals that trigger reward behaviour.
The answers could ultimately help improve therapy, both counselling and medications, for those with eating disorders.
"This research suggests there is probably a biological difference between males and females that we need to explore to understand risk factors and mechanisms," Professor Klump said.
- DAILY MAIL