Abstract: The invention describes one or more compositions for causing an increase in thermogenesis in mammals, comprising at least caffeine, hordenine and ?-phenylethylamine and optionally the addition of B vitamins. The caffeine is often provided from green coffee bean extracts and normally comprises from 0.0001 g to 0.30 g of caffeine from 0.00001 g to 0.1 g of hordenine from barley and from 0.00001 g to 1.0 g ?-phenylethylamine from cocoa beans. The present invention finally provides a method that may cause a simultaneous and synergistic increase in central nervous system activity assisted by the addition of vitamin B as well as thermogenesis in mammals prior to physical exercise, the method comprising providing a composition comprising a source of caffeine, hordenine and ?-phenylethylamine.