The skin of the fruit contains a substance called Hydroxycitric Acid (HCA), which is the active ingredient. Does Garcinia Cambogia Actually Work. Woman Smiling and Holding a Supplement I managed to find several research studies on Garcinia Cambogia, in both animals and humans.
According to some studies in rats, it can inhibit a fat producing enzyme called Citrate Lyase, making it more difficult for the body to produce fat out of carbohydrates (1). Other rat studies show increased levels of the neurotransmitter serotonin.