Anorexia nervosa is a psychological eating disorder characterized by an intense fear of weight gain and a preoccupation with being thin. People with anorexia nervosa starve themselves and excessively exercise in an attempt to lose weight. Symptoms include significant weight loss, yellow skin, low blood pressure, and depression. Treatment involves antidepressant medication, behavioral therapy, psychotherapy, and supportive care. The exact causes are unknown but genetics and social attitudes may play a role.