Abstract The eating disorders are a group of conditions, central to which is a disturbance of eating behaviour. The main diagnoses are anorexia nervosa and bulimia nervosa, in both of which there is an extreme concern with weight and shape. In anorexia nervosa, persistent dietary restriction leads to weight loss, which may be severe. In bulimia nervosa, the dietary restriction is interrupted by repeated episodes of binge eating (typically followed by self-induced vomiting) and weight is usually unremarkable. Both disorders may be accompanied by medical complications that present to physicians. Anorexia nervosa has the potential to be life-threatening because of the consequences of starvation. Patients may require medical attention for the correction of electrolyte disturbance and sometimes admission to a medical unit for refeeding. The main treatment of eating disorders is psychological. The prognosis of bulimia nervosa is generally good but is less positive for anorexia nervosa.