Daphnetin is a coumarin derivative, extracted from the different Daphne species, known to have anti-cancer, neuroprotective, anti-obesity, anti-inflammatory, anti-bacterial, and anti-malarial effects. However, the research on the anti-obesity effect of daphnetin is limited. Therefore, this study was conducted to determine the effects of daphnetin on lipid metabolism using an in vivo model, Caenorhabditis elegans. Treatment of 100μM daphnetin reduced fat compared to the control in wild-type C. elegans. The pumping rate has not been affected by daphnetin, suggesting daphnetin does not affect the food intake of worms. The bending rate also has not been affected, suggesting daphnetin does not affect the energy expenditure of worms. Mutants were tested to determine the fat-reducing mechanisms of daphnetin. The daf-2, daf-16, and aak-2 null mutants didn’t show a decrease in fat by daphnetin, suggesting daphnetin regulates fat accumulation in part via DAF-2, DAF-16, and AAK-2 dependently.