The present invention includes a method of activating irisin by administering to an individual in need of such treatment a composition comprising irisin-activating ingredients, thus increasing the conversion of white fat to BAT, and consequently, increasing metabolic rate and promoting weight loss. In an embodiment, the composition includes a Gynostemma pentaphyllum extract, a Polygonum cuspidatum root extract, capsaicinoids, and grains of paradise or constituents thereof. The composition may optionally comprise additional ingredients to activate the increased BAT, thus further increasing metabolic rate and furthering weight loss.