['To test whether weight loss may improve endothelial dysfunction in human obesity, we recruited 28 healthy obese subjects, aged 30-46 years, with BMI 30-43 kg/m(2).', 'Endothelium-dependent and -independent vasodilation were investigated by intra-arterial infusion of increasing doses of acetylcholine (ACh; 7.5, 15, and 30 microg x ml(-1) x min(-1)) and sodium nitroprusside (0.8, 1.6, and 3.2 microg x ml(-1) x min(-1)). Insulin resistance was estimated by homeostasis model assessment (HOMA). Weight loss was obtained by caloric restriction and physical activity.', 'We observed a significant reduction in BMI (from 33.1 +/- 4.2 to 27.5 +/- 4.5 kg/m(2), -16.9%, P < 0.0001) and in waist circumference (from 108.2 +/- 12.1 to 96.8 +/- 12.9 cm, -10.5%, P < 0.0001). Weight loss was also associated with a significant increase in ACh-stimulated forearm blood flow (FBF), from 7.4 +/- 2.8 to 12.9 +/- 3.4 ml. 100 ml(-1) of tissue x min(-1) kg/m(2) (P < 0.0001). Multivariate regression analysis demonstrated that the only independent predictor of FBF was HOMA, accounting for 44.5% of the variation, whereas the addition of BMI explained another 2.3% of the variation.'] Does weight loss in combination with physical activity improve endothelial dysfunction in human obesity?