Abnormal caloric requirements for weight maintenance in patients with anorexia and bulimia nervosa

This study tested previous findings that patients with eating disorders who attain normal weight have abnormal caloric requirements for maintaining weight.

Fifty-three female patients meeting the DSM-III-R criteria for anorexia nervosa and/or bulimia nervosa were divided into four subgroups, and their daily caloric intake was measured over a weight-stable period. Patients with anorexia nervosa (restricting and bulimic subtypes) were studied 4 weeks after refeeding and weight gain, when they had attained 95% of average body weight. Patients with normal-weight bulimia (previously anorexic or never previously anorexic) were studied 1-4 weeks after admission to an inpatient unit.

After weight restoration, restricting anorexic patients required significantly more calories per day to maintain weight than did bulimic anorexic patients, as measured with corrections for weight, body surface area, and fat-free mass. Previously anorexic normal-weight bulimic patients required significantly more calories per day to maintain weight than never-anorexic normal-weight bulimic patients, as measured with correction for weight but not with the other factors used to correct caloric intake.

To maintain stable weight after weight restoration, restricting anorexic patients require a significantly higher caloric intake than do bulimic anorexic patients. Differences in caloric needs between normal-weight bulimic patients with and without histories of anorexia may depend on the methods used to correct caloric requirements. Body surface area may be the most precise correction factor across different subgroups of eating disorder patients. Elevated caloric requirements, when coupled with reduced food intake, may particularly contribute to relapse in anorexic patients.