This study evaluated the effect of biocellulose and the diet formulation on reducing body weight gain of obese rats induced by high-fat diet for 10 weeks. Thirty male Sprague-Dawley rats were randomly assigned to high-fat diet group (OB-CON), high-fat diet group containing 5% biocellulose (OB-BIO), and high-fat diet group containing 5% dietary formulation (OB-DF). After feeding each diet for additional 10 weeks, body weight gains of OB-BIO and OB-DF groups were lower by 3.3 and 4.8%, respectively as compared with that of OB-CON group. Although not significant, measured values of the perirenal and visceral fat pads of OB-BIO and OB-DF groups were lower than those of the OB-CON group. The weight of interscapular brown adipose tissue did not show significant difference in all groups. The size of adipocyte in rats was lower in both OB-BIO and OB-DF groups. Thus, biocelluose and the diet formulation showed the anti-obesity effect.