RESTING ENERGY-EXPENDITURE, WEIGHT-LOSS, AND ALTERED BODY-COMPOSITIONIN HIV-INFECTION

Failure to downregulate resting energy expenditure (REE) as an adaptio n to anorexia or malabsorption is often stated as the major cause of w eight loss in individuals with AIDS. In a prospective study, REE was c ompared with weight changes in HIV-infected patients. The impact of al tered body composition on REE was reassessed by critical review of the literature. Patients were 65 male HIV-infected patients, 28 with rece nt weight loss (WL), and 37 who were weight stable (WS); 50/65 patient s had AIDS, and 29/65 had acute infections; 29 male healthy persons se rved as controls. Indirect calorimetry, prospective intake protocol, a nd bioelectrical impedance analysis were performed. Absolute REE was l ower in WL patients than in controls (1459 +/- 309 versus 1711 +/- 151 kcal/d, p < 0.001) and in WS patients (1625 +/- 402 kcal/d, p < 0.05) . REE/kg body cell mass (BCM) was higher in WL and WS than in controls (both p <0.01) due to lower BCM in both patient groups (p < 0.001). R EE (%Harris-Benedict) was not different among the three groups. Weight changes around the measurement were not correlated to REE (r(2) = 0.0 008, p = 0.82). REE was independent of diarrhea, acute infection, feve r, or caloric intake. REE had a stronger correlation to body weight an d to Harris-Benedict's prediction than to fat-free mass or BCM. REE ex plains <1% of weight changes. Many patients can downregulate REE as an adaption to anorexia and/or malabsorption. Higher REE/kg BCM does not signify hypermetabolism at the cellular level but can be explained by the maintenance of energy-consuming visceral tissue within the BCM du ring BCM loss.