The prevalence of obesity is expanding rapidly worldwide, making the disease a global burden with limited treatment options. The current obesity drug development trends suggest the possibility of reducing weight and reverse metabolic disturbances of obesity by controlling appetite. In this study, we screened more than 8000 plants from our plant library for the cannabinoid (CB1) receptor antagonists and identified Morus alba as a lead medicinal plant. Kuwanon G and Albanin G were isolated and identified from root-barks of Morus alba with 92% and 96% CB1 receptor ligand binding inhibitory activity, respectively. The bioflavonoid standardized extract was tested in the acute food intake study in rats at oral doses of 250 and 500 mg/kg for its appetite suppression activity. Diet-induced obesity in the C57BL/6J mice was used to evaluate the long-term food intake reduction activity and effect on the weight loss administered orally at 250 and 500 mg/kg for 7 weeks. Statistically significant and dose-dependent reduction in food intake was observed in both acute and long-term studies for the extract. Food intake reductions of 58.6% and 44.8% at 250 mg/kg and 50.1% and 44.3% at 500 mg/kg were observed at 1 and 2 h postfood provision, respectively. A 20% reduction in daily calorie intake was observed in the long-term study. Obese mice treated with the high dose of Morus root-bark extract showed 10.4 g (22.5%) and 7.1 g (16.5%) loss in body weight compared with the vehicle-treated obese animals (at week 7) and baseline, respectively. Statistically significant reductions in biochemical markers and visceral fat deposit were also observed. These results demonstrated that Morus alba extracts enriched in Kuwanon G, and Albanin G could be used alone to control appetite, manage body weight, and improve metabolic syndromes.