Objectives : This study was designed to determine the effects of the GGEx18 ethyl acetate fraction(EF) on body weight gain, feeding efficiency ratio, and obesity-related factors in plasma as well as histology of liver and adipose tissues using high fat diet-fed male C57BL/6N obese mice. Methods : 8 weeks old, high fat diet-fed obese male mice were divided into 5 groups: C57BL/6N normal, control, EF(1), EF(2) and EF(3). After mice were treated with EF for 9 weeks, we measured body weight gain, food intake, feeding efficiency ratio, fat weight, plasma leptin and lipid levels. We also analysed histology of liver and adipose tissues on high fat diet-fed male C57BL/6N obese mice. Results : Compared with control, EF-treated mice had significantly lower body weight gain and feeding efficiency ratio. Consistent with the effects on body weight gain, EF significantly decreased the adipose tissue weight compared with control. Consistent with the effects on feeding efficiency ratio, EF significantly decreased plasma leptin concentrations compared with control. EF reduced the size of adipocytes as well as hepatic lipid accumulation compared with control. EF seems to be safe since not only the plasma levels of ALT and AST are within the normal range, but also EF did not show any toxic effects on organs. EF(3) was most effective among EF(1), EF(2), and EF(3) at doses of 25, 50, and 100 mg/kg, respectively. Conclusions : These results demonstrate that EF effectively reduces body weight gain, feeding efficiency ratio in high fat diet-fed obese mice, leading to the modulation of obesity. In addition, EF decreases the size of adipocytes and improves plasma lipids and controls hepatic lipid accumulation, suggesting that EF may act as a therapeutic agent for obesity.