A mental disorder manifested by extreme fear of becoming obese and an aversion to food, usually occurring in young women and often resulting in life-threatening weight loss, accompanied by a disturbance in body image, hyperactivity, and amenorrhea.
Anorexia nervosa (AN) has been defined as a compulsive pursuit of thinness at the expense of health. It is characterized by steady weight loss, to and below 85% of normal weight for height, achieved by rigorous dieting, often supplemented by strenuous exercise and sometimes by self-induced vomiting or the use of diuretics or laxatives. Onset is typically during adolescence; 90% of patients are women. Estimates of prevalence range from 0.3–3% of girls and women between the ages of 10 and 25. Risk factors include white race, upper-class background, and a compulsive, perfectionistic personality. Body image is grossly distorted, with perception of a normal habitus, and even an emaciated one, as obese. Despite limited insight, patients are often highly manipulative, denying their dietary practices, shunning encounters with health care professionals, and choosing clothing that conceals their thinness. Physical consequences of AN, in addition to wasting of muscle and loss of subcutaneous fat, include anemia, electrolyte imbalance, bradycardia, hypotension, asthenia, exaggerated sensitivity to cold, constipation, and dryness and scaliness of skin with increased pigmentation and growth of lanugo. Women become amenorrheic and are at risk of osteoporosis and stress fractures or irreversible bone deformation, The female athletic triad (disordered eating, amenorrhea, and osteoporosis) is associated particularly with sports that emphasize low body weight, such as running, swimming, gymnastics, and figure skating. Cognitive-behavioral therapy and treatment with antidepressants, lithium, or other agents lead to remission in many patients, but the relapse rate is high. Severe cachexia or extreme dietary deviance may require hospitalization and intravenous correction of acute nutritional and electrolyte deficiencies. At least 50% of patients have persistent psychiatric problems throughout life, particularly with eating and sexuality. The mortality rate of AN is about 5%.
Reference: Stedman's Medical Dictionary