The influence of dietary fiber on determinants of metabolic syndrome is controversial. The objective of this study was to determine the effects of NUTRIOSE supplementation on insulin resistance and the determinants of metabolic syndrome in overweight men. In this double-blind, randomized, placebo-controlled study, we supplemented the diets of overweight Chinese men with 250�mL of fruit juice that contained NUTRIOSE (Test group: n = 60, age = 30.4�� 4.3�years, body mass index (BMI) = 24.5�� 0.2�kg�m^–2) or a maltodextrin placebo (Control group: n = 60, age = 31.6�� 4.1�years, BMI = 24.5�� 0.3�kg�m^–2) at a dosage of 17 g twice daily for 12�weeks. Daily caloric intake, body composition, blood chemistry, and blood pressure were evaluated every 4�weeks during the trial. Test subjects consumed fewer calories per day and had greater reductions in body weight, BMI, body fat percentage, and waist circumference than Control subjects. All markers of glucose metabolism improved in the Test group, with increases in adiponectin and reductions in glucose, insulin, homeostasis model assessment-estimated insulin resistance, glycosylated hemoglobin, and glycated albumin (all p�< 0.01). Similarly, all lipid measures improved with increases in high-density lipoprotein cholesterol and reductions in total cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, and triglycerides (all p�< 0.01). No changes were observed in systolic blood pressure between groups. Most components of glucose metabolism and the lipid profile were significantly better in the Test than in the Control subjects. No adverse events or gastrointestinal complaints were reported in either group. Supplementation with NUTRIOSE for 12�weeks is well tolerated, lowers insulin resistance, and improves determinants of metabolic syndrome in overweight men.