Diet-induced weight loss improves not only cardiometabolic risk markers but also markers of vascular function: a randomized controlled trial in abdominally obese men

Background: Many trials assessing effects of dietary weight loss on vascular function have been performed without no weight loss control groups and in individuals with obesity-related morbidities. Usually a limited set of vascular function markers has been investigated. Objective: The objective of this study was to examine effects of diet-induced weight loss on various vascular function markers and differences between normal-weight and abdominally obese men at baseline and after weight reduction. Design: Twenty-five healthy, normal-weight men (waist circumference: <94 cm) and 54 abdominally obese men (waist circumference: 102-110 cm) participated. Abdominally obese participants were randomly allocated to a dietary weight-loss or a no weight loss control group. Individuals from the weight-loss group followed a calorie-restricted diet for 6 wk to obtain a waist circumference <102 cm followed by a weight-maintenance period of 2 wk. The control group maintained their habitual diet and physical activity levels. The primary outcome was the change in brachial artery flow mediated vasodilation (FMD). Results: Compared with the control group, FMD did not change in the weight-loss group, but carotid-to-femoral pulse wave velocity tended to decrease by 0.5 m/s (P = 0.065). The retinal arteriolar caliber increased by 5 mu m (P < 0.001) and the arteriolar-to-venular ratio by 0.02 (P < 0.01). Soluble endothelial selectin and soluble intercellular adhesion molecule concentrations decreased (P < 0.001). Also, total cholesterol, low density lipoprotein cholesterol, triacylglycerol, glucose, insulin, C-peptide, homeostasis model assessment of insulin resistance, and blood pressure improved (P < 0.05 for all variables). Except for FMD, these markers differed at baseline between normal-weight and abdominally obese men but became comparable after weight loss. Conclusions: In abdominally obese men, dietary weight loss targeting a waist circumference of <102 cm improved retinal microvascular caliber, plasma biomarkers of microvascular endothelial function, and the more conventional cardiometabolic risk markers. Aortic stiffness tended to decrease, but FMD was not changed.