The effect of the hot water extract of defatted green tea seed cake (GTSE) on lipid metabolism and the underlying mechanisms of lipolysis in mature 3T3-L1 adipocytes were investigated. In this study, we found that the naringenin content of GTSE was 5.5 mg/g; however, catechins were not detected. The intracellular lipid droplets were stained with Oil Red O dye and quantified. Compared to the control, lipid accumulation was significantly decreased by 52%, and intracellular triglyceride (TG) level was reduced by 33% after treatment with GTSE at a concentration of 40 μg/mL. To determine the mechanism of reduction in TG content, we determined the level of fatty acid synthase (FAS), phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), and acetyl-coenzyme A carboxylase (ACC) in the cell model. Incubation of the 3T3-L1 adipocytes with GTSE stimulated AMPK and ACC phosphorylation in a dosedependent manner, and decreased the expression of FAS