Guarana is a naturally-occurring caffeine. Caffeine is a known diuretic, mild stimulant and appetite-suppressant. The caffeine suppresses the appetite and rids the body of water weight, then the combination of ma huang and caffeine speeds up the heart to give the feeling of added energy. Metabolite Metabolite, a similar product produced by a company called AIM, is widely marketed through pyramid-type schemes. HCA is a close relative of citric acid, the component that gives oranges, lemons, limes and other citrus fruits their characteristic tart flavor.
Citric acid is a common substance.
HCA, however, is found in only a few plant species. One of its main sources is the herb, Garcinia cambogia . HCA has shown some effect on appetite suppression in preliminary animal studies, but human studies have not duplicated these results. The herb has shown no effect on weight loss. In the double-blind study published in the Journal of the American Medical Association , half of the 135 study subjects received 1,500 mg of HCA per day, the other half a placebo.