The results of the study, which were published in the journal American Journal of Psychiatry, point to a region of the brain linked to anxiety and perfectionism.
University of Pittsburgh researchers said the finding may help the development of new treatments.
The study may also explain why people with anorexia nervosa are able to refuse food.
It is estimated one in 100 women between 15 and 30 years has anorexia.
The main symptom is the relentless search for thinning by rigid diets.
Anorexia is an eating disorder that can become life-threatening.
Dr. Kaye and his team analyzed the cases of 13 women who were recovering from anorexia and 13 healthy women.
All were asked to participate in a computer game, in which correct answers were rewarded financially.
At the same time, the researchers observed what was happening in the minds of women using a brain scanner called functional magnetic resonance imaging.
Concerned and perfectionists
During the game, the regions of the brain of each group lit up in different ways.
While the area of the brain devoted to emotional responses showed significant differences by winning and losing the game in healthy women with a history of anorexia patients expressed a small difference between victory and defeat.
Dr. Kaye said that, when you suffer from anorexia, this minimum difference could have an impact on the enjoyment of the food.
“For anorexic people, it is perhaps difficult to appreciate pleasure immediately, if does not feel much different from a negative experience”, said the specialist.
Another part of the brain called the caudate nucleus, which is involved in linking actions to outcome and planning, proved to be more active in women with a past with anorexia than members of the control group.
The Group of women who had suffered from the eating disorder tended to present obsessive and exaggerated concerns, they looked for rules where there were none and they were too tense by making mistakes, said Kaye.
“There are positive aspects of this type of temperament.” “Pay attention to the details and make sure things are done correctly as possible are constructive traits in careers such as medicine and engineering.”
However, develop extremely obsessive thoughts can be painful.
Doctor Ian Frampton of Exeter University, who has been conducting studies in patients with anorexia said: “These shows how important could be the brain for eating disorders”.
“There are many interconnections in the brain that makes someone vulnerable to develop eating disorders.”
Establish a cause neurobiological could help remove the stigma that surrounds the anorexia.
A spokeswoman for the Association of eating disorders, BEAT, said: “This shows how complex are eating disorders and stresses that they should be treated as a serious mental illness and not as a stupid diet that goes wrong”.