Modest visceral fat gain causes endothelial dysfunction in healthy humans

Objectives: The aim of this study was to determine the impact of fat gain and its distribution on endothelial function in lean healthy humans. Background: Endothelial dysfunction has been identified as an independent predictor of cardiovascular events. Whether fat gain impairs endothelial function is unknown. Methods: A randomized controlled study was conducted to assess the effects of fat gain on endothelial function. Forty-three normal-weight healthy volunteers were recruited (mean age 29 years; 18 women). Subjects were assigned to gain weight (approximately 4 kg) (n = 35) or to maintain weight (n = 8). Endothelial function (brachial artery flow-mediated dilation [FMD]) was measured at baseline, after fat gain (8 weeks), and after weight loss (16 weeks) for fat gainers and at baseline and follow-up (8 weeks) for weight maintainers. Body composition was measured by dual-energy X-ray absorptiometry and abdominal computed tomographic scans. Results: After an average weight gain of 4.1 kg, fat gainers significantly increased their total, visceral, and subcutaneous fat. Blood pressure and overnight polysomnography did not change after fat gain or loss. FMD remained unchanged in weight maintainers. FMD decreased in fat gainers (9.1 ± 3% vs. 7.8 ± 3.2%, p = 0.003) but recovered to baseline when subjects shed the gained weight. There was a significant correlation between the decrease in FMD and the increase in visceral fat gain (rho = -0.42, p = 0.004), but not with subcutaneous fat gain (rho = -0.22, p = 0.15). Conclusions: In normal-weight healthy young subjects, modest fat gain results in impaired endothelial function, even in the absence of changes in blood pressure. Endothelial function recovers after weight loss. Increased visceral rather than subcutaneous fat predicts endothelial dysfunction. (Fat Gain and Cardiovascular Disease Mechanisms; NCT00589498)