A method of increasing irisin levels in the body of a human, comprising administering to a human in need of weight loss a composition comprising about 200 mg to about 500 mg of a Gynostemma pentaphyllum extract, about 1 mg to about 100 mg of grains of paradise, and about 50 mg to about 150 mg of a Polygonum cuspidatum root extract, wherein the human has a body mass index (“BMI”) from about 23 to about 28, and wherein the metabolic rate of the human increased at least 200 kilocalories within 90 minutes after administration following daily administration of the composition for 28 days.