This study will evaluate the effects of a novel, non-pharmacologic intervention for the prevention of deleterious changes in bone density and strength in adolescents with anorexia nervosa (AN), a disease commonly treated with extended periods of bed rest and immobilization. The primary focus of the trial is to conduct a prospective short-term intervention to prevent an uncoupling of bone turnover in inpatients hospitalized for AN, and to determine the long-term effects of a biomechanical intervention on skeletal health in ambulatory adolescents with AN.