INCREASE IN DIET-INDUCED THERMOGENESIS AT THE START OF REFEEDING IN SEVERELY MALNOURISHED ANOREXIA-NERVOSA PATIENTS

Many reports describe the difficulty for anorexia nervosa patients to gain weight during refeeding. To assess whether an increase in diet-in duced thermogenesis (DIT) participates to this resistance, we studied DIT by indirect calorimetry in 11 severely malnourished anorexia nervo sa patients [body mass index (BMT; in kg/m(2)) = 13] to accomplish two purposes: 1) to compare DIT in a strict semistarvation state with tha t obtained after 1 wk refeeding, when metabolism is shifted to a dynam ic trend toward regaining weight, without significant change in body c omposition; 2) to study the effect on DIT of two energetic loads repre senting each one-third of the energy intake during semistarvation and refeeding, respectively: 1.25 and 2.92 MJ. To avoid bias, the two liqu id loads were infused intragastrically in a random double-blind fashio n. A significant increase in DIT during refeeding was observed for the two loads (204 +/- 23 kJ for the 1.25-MJ liquid meal and 482 +/- 78 k J for the 2.92-MJ one, P < 0.02). The higher the load, the larger the increase with refeeding (P < 0.001). This increment in DIT exceeded th e increase in active lean body mass and was poorly correlated with lea n body mass. These results provide clear evidence of a strong cellular ''waste'' mechanism in anorexia nervosa patients during the early pha se of refeeding, which enhances the adaptative resistance to overfeedi ng that we have already shown for resting energy expenditure.