Usefulness of visceral obesity (waist/hip ratio) in predicting vascular endothelial function in healthy overweight adults

Abstract

Vascular endothelial dysfunction (VED) is associated with obesity; however, its etiology remains controversial. By determining the predictors of fasting and postprandial endothelial function in overweight adults without other cardiovascular risk factors, we were able to investigate novel mechanisms directly linking obesity to VED. Thirty-two healthy adults (body mass index [BMI] ≥27 kg/m2) underwent determination of fasting low-density lipoprotein (LDL) particle size, high sensitivity C-reactive protein levels, anthropometric measurements, and endothelial function by flow-mediated dilation (FMD) of the brachial artery. Postprandial lipemia and FMD were measured 4 hours after ingestion of a high-fat meal. Blood pressures and fasting levels of lipoproteins, glucose, insulin, and fatty acids were within normal limits in all subjects. An abdominal fat pattern, as determined by an increased waist/hip ratio (WHR), was the sole significant predictor of FMD (r = −0.58, p = 0.001), despite no significant correlation between whole body obesity (BMI) and FMD. At comparable levels of BMI, obese subjects with a WHR ≥0.85 had a significantly blunted FMD compared with those with a WHR <0.85 (3.93 ± 2.85% vs 8.34 ± 5.47%, p = 0.016). Traditional coronary risk factors, C-reactive protein, postprandial lipemia, and LDL particle size did not predict FMD. We found no appreciable alteration in the postprandial state from fasting FMD (6.31 ± 4.62% vs 6.25 ± 5.47%, p = 0.95). The same results were found when women were analyzed alone. Increased abdominal adiposity determined by a simple WHR is a strong independent predictor of VED even in healthy overweight adults; this is a finding unexplained by alterations in conventional risk factors, systemic inflammation, or the atherogenic lipoprotein pattern.