['Little is known about how visceral adipose tissue (VAT) influences circulating apolipoprotein B (apoB) levels, which reflect atherogenic risk. We have examined the effects of a 1-year lifestyle modification program on plasma apoB levels in viscerally obese men and compared post-intervention levels to those of a reference group of lean healthy men.', 'Fasting plasma apoB levels were measured in 107 non-diabetic, viscerally obese men, before and after a 1-year lifestyle intervention program aiming at improving nutritional and physical activity/exercise habits.', 'After the intervention, subjects significantly decreased their volume of VAT (Δ = -26 ± 18%, p < 0.0001) measured by computed tomography and significantly, but modestly reduced their fasting apoB levels (Δ = -3 ± 14%, p = 0.04). When compared to the reference group, men in the intervention group still had higher apoB levels suggesting that they did not "normalize" their apoB concentrations to the level of the healthy non-obese reference men. To further explore the relationship between VAT and apoB, men in the intervention group were stratified according to quartiles of VAT achieved after the intervention. Only men of the lowest quartile of VAT (corresponding to 844 ± 42 cm(3), similar to the value of the reference group; 809 ± 52 cm(3) of VAT) showed plasma apoB levels which were similar to those of the reference group (0.98 ± 0.21 vs. 0.99 ± 0.24 g/L, NS, for lowest VAT quartile and reference group, respectively).'] Is normalization of visceral adiposity required to normalize plasma apolipoprotein B levels in response to a healthy eating/physical activity lifestyle modification program in viscerally obese men?