Eating disorders are serious illnesses affecting 1–2% of young women. Patients may present to any doctor, sometimes atypically (e.g. unexplained weight loss, food allergy, infertility, diarrhoea), delaying diagnosis and leading to needless investigation. The cardinal signs are weight loss, amenorrhoea, bingeing with vomiting and other compensatory behaviours, and disturbances in body image with an exaggeration of the importance of slimness. When other causes have been excluded, useful investigations are serum potassium, bone mineral density scanning and pelvic ultrasound. In emaciated patients multiple systems may fail with pancytopaenia, neuromyopathy and heart failure. Clinical assessment of muscle power is used to monitor physical risk.

Treatment may involve individual, group or family sessions, using cognitive-behavioural, psychodynamic and family approaches. More severe or intractable illness is treated with day care, with in-patient care in a medical or specialist psychiatric unit reserved for the most severely ill patients. Antidepressants have a place in the treatment of bulimia nervosa unresponsive to psychological approaches, and when severe depressive symptoms develop. The children of people with eating disorders may have an increased risk of difficulties. Support for the patient and family, and effective liaison between professionals, are essential in the treatment of severe eating disorders.