This study will determine the importance and the level of physical activity among women with anorexia nervosa, both during inpatient treatment and 1 year after hospital discharge.

Anorexia nervosa is a disorder that causes people to maintain an unhealthily low body weight, often through eating too little or exercising too much. Treatment for anorexia nervosa often begins with a supervised program for raising a person's weight to a healthy level. This study will monitor activity levels during inpatient treatment and for 1 year after hospital discharge in order to determine the impact of physical activity on weight gain during anorexia treatment.

Participation in this study will last until 1 year after participants are discharged from inpatient treatment for anorexia nervosa. Discharge is based on each person's progression in treatment and may vary among participants. During the study, participants will have their activity monitored two or three times-at low weight, at 90% of ideal body weight (IBW), and, if the participant is living near the study clinic, within 6 weeks after discharge from the hospital. Two monitoring devices will be attached to participants continuously for 48 hours for the first two assessments and for 72 hours for the third. The first device is a SenseWear armband, which is a wireless monitor strapped to the back of the upper arm that measures body movement and body temperature. The second is an Intelligent Device for Energy Expenditure and Activity (IDEEA) monitor, which consists of five sensors that will be taped to each participant's feet, thighs, and chest. The device measures activity levels and energy expenditure. Participants will complete a blood draw within 1 week of completing activity monitoring assessments. Participants will also complete a computer "work" task at two time points-at 75% of IBW and at 90% of IBW. This task will last 40 minutes and will involve tapping a keyboard in order to earn rewards. Adult participants will also complete a dual X-ray absorptiometry (DXA) test to assess body composition when 90% IBW is reached.

Follow-up assessments will occur 1, 2, 4, and 8 months after discharge. These will involve a phone call or in-person visit in which health, body weight, and eating disorder symptoms are discussed. One year after discharge, participants will attend an in-person assessment that will involve completing questionnaires and an interview. Healthy participants will be recruited as a control group, and these participants will complete one session of activity monitoring, one blood draw, and self-rating forms without follow-up measurements.

Inclusion Criteria:

• Anorexia nervosa (except amenorrhea), as defined by DSM-IV
• Medically and psychiatrically stable

Exclusion Criteria:

• Significant current or past medical illness, including diabetes mellitus and heart disease
• Current or lifetime history of schizophrenia, bipolar disorder, or other psychotic disorder, as defined by DSM-IV-TR
• Suicidal ideation or suicidal behavior within the past 3 months
• Drug or alcohol abuse in last 6 months
• Taking psychotropic medication
• Pregnant

Patients with anorexia nervosa participating in an inpatient treatment program