Anorexia nervosa and bulimia nervosa may be associated with serious medical complications (Pomeroy & Mitchell, 1989). The restoration of metabolic and physiological homeostasis is the first step in the treatment of a patient with an eating disorder. Until this is accomplished, the patient cannot benefit from nutritional and psychological interventions. In anorexia nervosa, medical consequences are primarily related to the effects of voluntary starvation. Immediate danger may derive from hypophosphatemia, bone marrow failure, cardiac decompensation, and shock. Patients with bulimia nervosa more often experience severe fluid and electrolyte abnormalities due to purging behavior, and emergency situations may include severe hypovolemia, depletion of total body potassium, and cardiac arrhythmias (Comerci, 1990). Fortunately, most of the medical disturbances are not severe, and most resolve quickly after symptom remission. Table 4.1 summarizes the causes of the major medical complications in eating disorders.