Weight loss ≥ 5 percent is sufficient to significantly reduce health risks for obese people; therefore, development of novel weight loss compounds with reduced toxicity is urgently required. After screening of natural compounds with antiadipogenesis properties in 3T3-L1 cells, we determined that kahweol, a coffee-specific diterpene, inhibited adipogenesis. Kahweol reduced lipid accumulation and expression levels of adipogenesis and lipid accumulation-related factors. Levels of phosphorylated AKT and phosphorylated JAK2, that induce lipid accumulation, decreased in kahweol-treated cells. Particularly, kahweol treatment significantly increased AMP-activated protein kinase (AMPK) activation. We revealed that depletion of AMPK alleviated reduction in lipid accumulation from kahweol treatment, suggesting that inhibition of lipid accumulation by kahweol is dependent on AMPK activation. We detected more rapid reduction in blood glucose levels in mice administrated kahweol than in control mice. We suggest that kahweol has anti-obesity effects and should be studied further for possible therapeutic applications.