The methanol extract of Dypsis lutescens leaves showed inhibitory effects on lipase activity in vitro and on triglyceride accumulation in 3T3-L1 pre-adipocytes. Further experiments using the extract on mice demonstrated a suppressive effect on the postprandial elevation of blood triglyceride level and an anti-obesity effect on obese mice induced by a high-fat diet. D. lutescens will accordingly be useful for preventing obesity.