In the past decade, patients with anorexia nervosa have been subdivided by the presence or absence of binging-and-purging behavior. Psychologic, physiologic, and premorbid weight differences have also been discovered between these subgroups. We now report that nonbulimic anorectics required 30-50% more caloric intake than bulimic anorectics to maintain a stable weight. This difference in caloric intake was independent of phase of illness; it was present at low weight and at intervals after weight restoration. Subjects were closely supervised on an inpatient hospital ward so that they could not binge or purge. Motor activity did not appear to explain these alterations in caloric requirements. Such differences in caloric intake could be trait related or a consequence of many years of starving or binging behavior. These findings are clinically relevant for advising eating disorder patients of caloric requirements necessary to maintain a normal weight.