Energy intake and body composition in anorexia and bulimia nervosa.

Energy intake during the weight gain phase and the weight maintenance phase was examined in three groups of inpatients: 64 anorectic restrictors (AN-R), 37 anorectic bulimics (AN-B), and 74 normal-weight bulimics (BN). The influence of body composition and other variables such as weight, exercise, and bingeing and purging frequencies on energy intake was analyzed. Eating disorder subgroups were found to differ in energy intakes to gain weight and to maintain weight within a target weight range. Anorectic restrictors consumed significantly more energy to gain weight than did the anorectic bulimics (a mean of 3055 kcals per day vs. a mean of 2788 kcal per day). Energy intake for weight gain was inversely related to admission body mass index (BMI) and to admission fat-free mass. Bingeing and purging frequencies did not predict caloric intake for either weight gain or maintenance for anorectics. Energy intake of the anorectic patients when they were maintaining weight within a target weight range did not differ between restrictors and anorectic bulimics (means of 2204 and 2134 kcal/day, respectively). Energy needed to maintain weight within a target weight range was predicted by the amount of fat-free mass at target weight and by the mean number of calories ingested per week during weight gain. Bulimics consumed fewer calories than either of the two anorectic groups during the weight maintenance phase (1538 kcal/day). Other than BMI at hospital admission, bulimics' energy intakes were unrelated to all demographic and eating disorder-related variables, including body composition.