Background: The refeeding process is a particularly dangerous time for some anorexia nervosa (AN) patients. Great physiologicatress can occur from imposing a large caloric intake on a body dealing with the effects of long-term starvation. Accurate predictive equations of basal metabolic rate (BMR) are needed to ensure AN patients gain weight at a safe rate.
Methods: Patients with AN undergoing strictly controlled nutritional rehabilitation on an inpatient unit were examined for changes in BMR via indirect calorimetry. Seven female patients were assessed shortly after inpatient admission. Follow-up measures of weight and BMR were obtained after three weeks of refeeding treatment comprised of approximately 3500 kcal/day.
Results: Body mass index (BMI) increased in all subjects from a median 13.7 kg/m2 at baseline to 15.2 kg/m2. BMR also increased from a median of 1000 kcal/day to 1220 kcal/day. The Owens and Mifflin equations were moderately accurate (within 10%) of predicted BMR at baseline and 3-week follow-up, and the Harris-Benedict equation was very accurate (within 2%) at 3-week follow-up only.
Conclusions: These results may guide nutritional therapies for AN by demonstrating the suppression of metabolism induced by calorie restriction as well as its relatively prompt rebound to expected values with weight gain. Derivation of accurate predictive equations for use during the early refeeding period is needed.