Anorexia nervosa is an eating disorder of unknown etiology. It is associated with multiple medical and psychosocial complications. Patients are unable to maintain a body weight of at least 85% of ideal weight due to restriction of food intake, exercising, binge eating, and/or purging. Prompt diagnosis and treatment are critical as anorexia nervosa has significant mortality and morbidity. Weight loss and malnutrition cause serious injuries to multiple organ systems. Ninety percent of cases are seen in females. Onset is most common between adolescence and young adulthood. In males, anorexia nervosa is most common in athletes and men who have sex with men. Look for a tendency to over-exercise. The preferred body image is muscularity.

Patients with this disorder may have an increased risk of various general medical conditions.