Anorexia Nervosa (AN) is a psychiatric illness that is characterized by extreme weight loss and severe body image distortions. In this study, we are examining changes in body composition, metabolic rate, and reproductive function before and after treatment for AN. More specifically, we are testing the hypotheses that 1)Weight-restored patients with AN have elevated resting energy expenditure (REE) compared to controls, 2) Weight-restored patients with AN have a central disposition of body fat compared to controls, 3) Weight-restored patients with AN who gain the most fat centrally will have the least improvement on psychological measures, 4) Weight-restored patients with AN will have leptin levels out of proportion to body fat mass. It will also investigate the relationship between REE and leptin with respect to the return of menses.