The binge-eating disorder bulimia may, in some cases, be linked to a sex hormone imbalance, research suggests.
Bulimia is usually treated with psychological techniques
Bulimia is normally viewed as a mental condition and treated with psychological therapies.
However, Dr Sabine Naessén, from the Karolinska Institutet suggests some women with the condition may have too much of the male hormone testosterone.
Half the bulimics treated for this imbalance reported less hunger, and fewer cravings for fatty, sugary food.
Dr Naessén claims that three out of 21 bulimics treated this way became completely free of the eating disorder.
Bulimia involves compulsive overeating, and is probably the most common form of eating disorder. It is approximately 10 times more common in women as men.
Normal treatments involve cognitive behavioural therapy, psychological counselling which looks to uncover deep-rooted causes for problems.
Antidepressants are often prescribed for the illness.
However, some outward signs of hormonal imbalance were apparent in a group of 77 bulimics examined by Dr Naessén.
The bulimics were more likely to report menstrual problems, excess body hair, and polycystic ovarian syndrome than women without the eating disorder.
The theory was tested in 21 women who had outward signs of hormone imbalance, and were given the a version of the contraceptive pill containing the female sex hormone oestrogen.
The effect of this would be to reduce levels of testosterone in the body. The study found that taking the hormone was linked to a reduction in bulimic 'symptoms' over a three month period in approximately half the women involved.
Dr Naessén said: "We have shown that one third of female bulimics have metabolic disorders that may explain the occurrence of the eating disorder.
"These disorders may in certain cases express the hormonal constitution of the patient, rather than any mental illness.
"Hormone treatment may very well be an alternative to cognitive behavioural treatment."
Steve Bloomfield, from the Eating Disorders Association, said that it was likely that only relatively few women would benefit from hormone treatment.
But he said: "We welcome this kind of research because it helps us to understand the issues behind bulimia nervosa, which is still very poorly understood.
"It's something that needs to be investigated in more detail."