Abstract: Obejective To study the effects of magnolol on body weight and insulin resistance of high-fat-fed rats and to discuss the possible mechanism. Methods SD rats were randomized into 4 groups: (1) normal control group fed with ordinary diet and administered normal saline, (2) high-fat-fed group administered normal saline, (3) and (4) groups fed with high fat diet and administered high and low concentration of aqueous suspension of magnolol diluted by normal saline respectively. Food intake was monitored daily and body weight was weighed weekly at the set time. At the end of the eighth week, All rats were fasted for 12 hours to collect blood for measuring biochemical Indexes, including glucose, insulin, free fatty acid(FFA), total antioxidative ability（T-AOC）, malondialdehyde(MDA) and so on . Result The body weights of rats in low dose group administered magnolol were lower than that of high-fat-fed group from the fourth week on（P<0.05）. Compared with high-fat-fed group, the serum levels of insulin, FFA and MDA reduced in each group administered magnolol（P<0.05）. Conclusion Magnolol can inhibit the weight gain caused by high-fat diet, reduce serum levels of MDA, FFA and insulin and improve the inlusin resistance and metabolism disorders.

Key words: Obesity, High-fat diet, Magnolol, insulin resistance