Bulimia nervosa, as described in ICD-10, is an eating disorder which shares many psychological features with anorexia nervosa, including an excessive preoccupation with body shape and weight. Bulimia nervosa is characterized by repeated bouts of overeating, which are followed by unhealthy methods of attempting to prevent weight gain. These include vomiting, strict dieting, excessive exercise and using laxatives or diuretics, which can cause disturbances of body electrolytes and physical complications. A history of an earlier episode of anorexia nervosa is often present.