['The relative contributions of the different classes of antiretroviral therapy (ART), HIV infection per se, and aging to body shape changes in HIV-infected patients have not been clearly defined in longitudinal studies.', 'Since September 1999, men enrolled in the Multicenter AIDS Cohort Study have undergone measurements of body mass index (BMI) and body circumferences at each semi-annual visit. The effect of HIV-serostatus and cumulative exposure to the three major ART classes on changes in anthropomorphic measurements occurring between 1999 and 2004 among HIV-infected and HIV-uninfected men were determined using linear mixed effects regression models.', 'At baseline, average BMI and circumference measurements were greater in HIV-uninfected men (n = 392) than HIV-infected men (n = 661) (BMI, 27.3 versus 25.3 kg/m; waist, 96.4 versus 90.2 cm; hip 101.3 versus 95 cm, thigh 54.1 versus 50.8 cm; arm 33.3 versus 31.7 cm, P < 0.001 for each comparison). Cumulative nucleoside reverse transcriptase inhibitor (NRTI) exposure, but not protease inhibitor or non-nucleoside reverse transcriptase inhibitor exposure, was associated with statistically significant changes in BMI (-0.11 +/- 0.04 kg/m per year) and in circumferences of waist (-0.27 +/- 0.07 cm/year), hip (-0.24 +/- 0.05 cm/year), and thigh (-0.16 +/- 0.03 cm/year) over the 5 years of follow-up. Independent of ART exposure, HIV-infected men had a more rapid increase in waist circumference over the study interval than did the HIV-uninfected men (difference 0.33 +/- 0.15 cm/year, P = 0.02).'] Are longitudinal increases in waist circumference associated with HIV-serostatus , independent of antiretroviral therapy?