We evaluate the effect of supplementation, at 300 mg kg(-1) body weight (BW), with the antioxidants α-lipoic acid (AL), betaine (BT), l-carnitine (LC), and the combination of these and exercise on obesity induced by a 9 week high-fat diet (HFD) in mice. Healthy 5 week-old male C57BL/6J mice were divided into 9 groups: (1) CON, control group fed with a commercial mice chow containing 10% crude fat; (2) HFD, high fat diet group fed with a commercial mice chow containing 60% crude fat; (3) HFD-AL, HFD group fed with AL; (4) HFD-BT, HFD group fed with BT; (5) HFD-LC, HFD group fed with LC; (6) HFD-SW, HFD with swimming as an exercise; (7) HFD-SWAL, HFD-AL with swimming; (8) HFD-SWBT, HFD-BT with swimming, and (9) HFD-SWLC, HFD-LC with swimming. The BW of mice with LC and swimming reduced the increase of BW after 9 weeks. Relative adipose tissue weights were reduced by the combinations of antioxidant supplementation and swimming. Levels of serum glucose and leptin were reduced in the HFD-SWLC group when compared with the HFD group. Serum triglyceride and total cholesterol and the size of adipose were also decreased in the HFD-LC and HFD-SWLC groups. These results show that LC at a dose of 300 mg kg(-1) BW was the most effective for reducing fat accumulation in mice with HFD for 9 weeks. In addition, exercise should be given in combination to enhance the BW reduction and serum lipid level.