Prebiotic foods have an important role in health well-being, especially for treating overweight or obesity by promoting gut microbiota to improve antioxidant activity and fat metabolism. We aimed to investigate the effect of prebiotic capsules containing anthocyanin, inulin and rice bran extract on antioxidant, leptin and insulin resistance, and fat metabolism of overweight or obese subjects. The research was a randomized double-blinded controlled trial. Sixty overweight or obese subjects were randomly allocated into two groups; 1) 350 mg/prebiotic capsule (prebiotic group) or 2) 350 mg/maltodextrin (placebo group), 3 capsules after each meal and before going to bed (4.2 g.day-1) for 30 days. Before and after 30 days of supplementation, anthropometry and body composition were measured. Blood samples were collected to analyze ascorbate, glucose, lipid profiles, leptin and insulin concentrations. An expired gas was collected for 5 min to determine substrate utilization. The results showed prebiotic capsules increased plasma ascorbate concentration (placebo group: before 34.6 ± 3.33 and after 45.2 ± 4.48 μmol/L; treatment group: before 35.7 ± 4.43 and after 62.3 ± 6.47 μmol/L, 95% CI 16.1(4.27-27.9), p-value < 0.05). Comparing within group, hip circumference, lipid profiles, and leptin and insulin concentrations were significantly decreased with prebiotic supplementation comparing to the baseline data (p-value < 0.05). However, there were no significant changes from baseline in fat and carbohydrate oxidation rates, plasma glucose, liver and kidney functions within and between groups (p-value < 0.05). In conclusion, supplementation of prebiotic capsule containing 1.89 g anthocyanin, 1.89 g inulin and 0.42 g rice bran per day for 30 days increased plasma ascorbate concentration in overweight or obesity subjects. Daily supplementation of 4.2 g prebiotics for 30 days did not cause liver and kidney dysfunctions. However, either higher dose or longer duration of the supplementation is warranted to show more variables those are significant and to confirm the safety.