Cross-sectional and longitudinal evaluation of body composition in men with HIV infection.

Body wasting is an increasingly prevalent AIDS-defining condition and an independent risk factor for mortality in patients infected with HIV. Largely on the basis of studies conducted early in the epidemic, HIV-associated wasting has been assumed to feature a disproportionate loss of lean tissue. We report the results obtained from cross-sectional and longitudinal studies that differ from these earlier observations. In a cross-sectional analysis, weight and body composition determined by dual-energy x-ray absorptiometry and bioelectrical impedance analysis in 32 HIV-infected men with documented weight loss of > or = 10% were compared to those in 46 HIV-positive men without significant weight loss and 32 HIV-negative controls. Fat, lean body mass (LBM), and body cell mass (BCM) were significantly lower in men with weight loss relative to controls (p < 0.001 for fat and BCM; p = 0.01 for LBM). Two thirds of the difference in weight was fat. For the longitudinal analysis, the composition of weight lost over time was evaluated in paired measurements in men grouped by body fat content (<15% or >15%, n = 10 per group). Weight loss in patients with baseline fat of more than 15% was only 16% LBM, but the composition of weight lost in men with baseline fat of less than 15% was 70% LBM. We conclude that progressive decreases in fat and lean tissue occur in men with HIV infection, with the composition of weight lost depending on baseline fat content. These results argue against the widely held notion that HIV-associated wasting is characterized by preservation of fat at the expense of lean tissue.