Mice treated with the drug tended to maintain their weight when free to eat and exercise, a study indicated.
First author Stephanie Klenotich, graduate student at the University of Chicago Biological Sciences, said the findings were encouraging in the fight against anexoria nevosa, a common and occasionally fatal eating disorder.
"We found over and over again that olanzapine was effective in harsher conditions, less harsh conditions, adolescents, adults -- it consistently worked," Klenotich said in a statement.
The study published in Neuropsychopharmacology found a low dose of olanzapine did not decrease overall running activity in the mice, indicating that sedative effects of the drug were minimal.
In future experiments, the researchers said, they hope to use different drugs and genetic methods to determine exactly how olanzapine is effective against symptoms of anorexia nervosa, perhaps pointing toward a better drug without the negative image or side effects of an anti-psychotic.
"Anorexia nervosa is the most deadly psychiatric disorder, and yet no approved pharmacological treatments exist," said senior author Stephanie Dulawa, assistant professor at the University of Chicago Medicine.