The study was carried out to investigate the anti-obesity effects of Aegle marmelos leaves extracts and its phytochemical constituents in vitro and in vivo. The dichloromethane (DCM), ethyl acetate (EtOAc) and n-butanol extracts of A. marmelos leaves were studied for their lipolytic effect. Lipolysis was measured by determining the amount of glycerol released at 12 h and 24 h at 50 μg/ml and 100 μg/ml concentrations. Phytochemical investigation of the most active DCM extract yielded 14 compounds. The isolated compounds were evaluated for their lipolytic effects at 50 μM and 100 μM. The most active compounds, umbelliferone and esculetin were further screened for their antiobesity effects in vivo in the high fat diet (HFD) induced obese rat model. Umbelliferone and esculetin reduced body weight, total triglyceride (TG), total cholesterol (TC) and glucose level in their respective HFD groups. A. marmelos DCM extract and compounds isolated from it have the potential of counteracting the obesity by lipolysis in adipocytes.