Garcinia is a small to medium-sized tree that grows in India and Southeast Asia. The fruit rind contains the chemical hydroxycitric acid (HCA) and is used to make medicine. Don't confuse Garcinia with Garcinia hanburyi (gamboge resin). People take Garcinia by mouth for weight loss, exercise performance, joint pain, bloody diarrhea, to increase bowel movements, and for treating worms and parasites. How does it work? Garcinia contains the chemical hydroxycitric acid (HCA). Developing research suggests that HCA might prevent fat storage, control appetite, and increase exercise endurance; however, whether these effects occur in humans is unclear.