Various forms of fermented soybean products are well documented for their health benefits. The efficacy of anti-obesogenic effect of Doenjang, one of the most commonly used seasonings in Korean cuisine, has been reported only in animal models; thus, an evaluation of Doenjang needs to be conducted in human studies. We aimed to test the hypothesis that Doenjang supplementation reduces body weight and changes body composition in overweight adults. A total of 51 overweight adults participated in this study. A group of males with BMI ${geq}23kg/m^2$ and waist to hip ratio (WHR) ${geq}$ 0.90, and a group of females with BMI ${geq}23kg/m^2$ and WHR ${geq}$ 0.85 were randomly assigned to either a Doenjang supplement (9.9 g dry/day) group or a placebo group for a 12-week randomized, double-blind and placebo-controlled study. Anthropometric parameters, abdominal fat distribution by computerized tomography (CT) and blood components were measured before and after the intervention period. After the 12-week study, the Doenjang supplementation group had significant reductions in body weight (kg), body fat mass (kg) and body fat (%) compared to the placebo group, the supplementation of Doenjang resulted in a significant reduction in visceral fat ($cm^2$), although no changes were observed in total and subcutaneous fat are as ($cm^2$), serum lipid profiles and dietary intakes. The present study demonstrated that daily supplementation of 9.9 g dry/day of Doenjang for 12 weeks reduces body weight and visceral fat in overweight adults.