Anorexia nervosa is a challenging disorder to treat, both from a medical and a psychiatric standpoint. Part of the clinical difficulty is based on the patients ardent desire to resist meaningful weight restoration, and the debilitating fear of food which defines this disorder. However, there are also a litany of medical complications which can interfere with the refeeding process and which affect many different body systems. One particularly concerning sequela of this refeeding is known as the refeeding syndrome. This potentially fatal syndrome most commonly occurs with aggressive refeeding programs that do not incorporate close surveillance for the signs and symptoms of the newly acquired anabolic condition. Without early detection and intervention, progressive cardiopulmonary failure can occur. Cautious and restrained provision of calories together with vigilant oversight and checking of electrolytes on a frequent basis will prevent this sobering syndrome. The biochemical, cardiac, and gastrointestinal systems are most prominently affected during early periods of weight restoration. However, weight restoration remains the key to a successful treatment outcome in patients with anorexia nervosa, and thus, familiarity with these issues is imperative for the caregivers of anorectic patients.