Gastrointestinal and nutritional aspects of eating disorders

Anorexia nervosa (AN) and bulimia nervosa (BN) are potentially fatal eating disorders which primarily affect adolescent females. Differentiating eating disorders from primary gastrointestinal (GI) disease may be difficult. GI disorders are common in eating disorder patients, symptomatic complaints being seen in over half. Moreover, many GI diseases sometimes resemble eating disorders. Inflammatory bowel disease, acid peptic diseases, and intestinal motility disorders such as achalasia may mimic eating disorders. However, it is usually possible to distinguish these by applying the diagnostic criteria for eating disorders and by obtaining common biochemical tests. The primary features of AN are profound weight loss due to self starvation and body image distortion; BN is characterized by binge eating and self purging of ingested food by vomiting or laxative abuse. GI complications in eating disorders are common. Recurrent emesis in BN is associated with dental abnormalities, parotid enlargement, and electrolyte disturbances including metabolic alkalosis. Hyperamylasemia of salivary origin is regularly seen, but may lead do an erroneous diagnosis of pancreatitis. Despite the weight loss often seen in eating disorders, serum albumin, cholesterol, and carotene are usually normal. However, serum levels of trace metals such as zinc and copper often are depressed, and hypophosphatemia can occur during refeeding. Patients with eating disorders frequently have gastric emptying abnormalities, causing bloating, postprandial fullness, and vomiting. This usually improves with refeeding, but sometimes treatment with pro-motility agents such as metoclopromide is necessary. Knowledge of the GI manifestations of eating disorders, and a high index of suspicion for one condition masquerading as the other, are required for the correct diagnosis and management of these patients.