Several studies in the past suggest that individuals who have or had anorexia nervosa may have alterations in brain serotonin. Serotonin seems to play an important role in regulating anxiety, mood, and other symptoms found in anorexia nervosa. We will be using a technology called Positron Emission Tomography (PET), which is a method used to take pictures of the body, in this case, the brain. Study participants will undergo two baseline PET scans on the first day of the study. They will then be given a medication called fluoxetine (also know as Prozac) to take for 8 weeks. At the end of the 8th week, they will return for a third PET scan. By comparing the brain scans, before and after fluoxetine treatment, we can understand more about how treatment with fluoxetine affects the serotonin receptors in the brain. We will be comparing brain serotonin system in women who have recovered from anorexia with healthy control women who have never had an eating disorder in order to gain a better understanding of changes in the serotonin system associated with eating disorders. This study may help shed light on how to make fluoxetine a more effective treatment for anorexia nervosa.