Sulforaphane, a phytochemical in broccoli sprouts, is known to exert effects of cancer prevention by detoxicating chemical compounds taken into the body and by enhancing anti-oxidation ability. In the present study, experiments with mice demonstrate that sulforaphane ameliorates obesity, the conclusion based on the two functions of sulforaphane newly uncovered; amelioration of obesity through enhancing energy consumption by browning of adipocytes, and reduction of metabolic endotoxemia through improving gut bacterial flora.