Also known as 1,3,7-trimethylxanthine; methylxanthine. An alkaloid and central nervous system stimulant found in coffee, tea, cola nuts, guarana and yerba mate. Caffeine can enhance exercise performance, and also has mild thermogenic effects. Because of these effects, caffeine is added to a wide variety of energy drinks, weight loss supplements and pre-workout boosters. Caffeine is addictive, and both caffeine intoxication and withdrawal are recognized psychiatric disorders.