Symptoms of the upper and lower gastrointestinal (gastrointestinal) tract have been described in anorexia nervosa and bulimia nervosa. Studies focusing on general outcome and medical comorbidity describe a worse outcome in the binge eating/purging subtype of anorexia nervosa compared to the restricting subtype. Both anorexia nervosa subtypes experience substantial delays in gastric emptying as well as constipation. These gastrointestinal disturbances may play a role in anorexia nervosa patients' difficulties with refeeding and weight restoration. Bulimia nervosa patients showed increased gastric emptying capacity, with delayed gastric emptying and diminished gastric relaxation. In addition, diminished release of cholecystokinin and abnormalities in enteric autonomic function were found in bulimia nervosa patients. These factors may play a role in the perpetuation of the disease. Gastrointestinal disturbances develop secondary to the disordered eating behaviour and the concomitant malnutrition and subside mostly with the resumption of normal food intake and body weight. Knowledge of these changes may be of critical importance in avoiding misdiagnosis and successful therapy.