Energy cost of physical activity in patients with anorexia nervosa

To assess the amount of energy cost for a standardized physical activity, a ctivity-induced thermogenesis (AIT) was measured in eight hyperactive and e ight sedentary patients with anorexia nervosa as well as in 14 sport studen ts and 14 sedentary controls. Resting metabolic rate (RMR) and AIT were mea sured by indirect calorimetry. RMR was measured after an overnight fast and began 20 min after the placement of the hood and lasted for 20 min; For th e next 10 min subjects had to ride a recumbent bicycle ergometer (25 W) and AIT was measured. Absolute RMR in both anorectic groups was significantly lower than in both normal weight groups, but after adjusting for lean body mass (LBM) RMR did not differ among the groups. Absolute AIT was significan tly lower in hyperactive anorectic patients and in sport students compared to the controls. After adjusting for LBM AIT was still significantly lower in the hyperactive anorectic group and in the group of sport students compa red to the control group. These results indicate that despite severe underw eight and biological changes in muscles anorectic patients still have an en ergy sparing metabolism during moderate physical activity. Copyright (C) 20 00 John Wiley & Sons, Ltd and Eating Disorders Association.