HCA, extracted from the rind of the Garcinia cambogia fruit grown in Southeast Asia, has a chemical composition similar to that of citric acid (the primary acid in oranges and other citrus fruits). Preliminary studies in animals suggest that HCA may be a useful weight-loss aid.^{1, 2} HCA has been demonstrated in the laboratory (but not yet in clinical trials with people) to reduce the conversion of carbohydrates into stored fat by inhibiting certain enzyme processes.^{3, 4} Animal research indicates that HCA suppresses appetite and induces weight loss.^{5, 6, 7, 8} However, a double-blind trial found that people who took 1,500 mg per day of HCA while eating a low-calorie diet for 12 weeks lost no more weight than those taking a placebo.⁹ A double-blind trial of Garcinia cambogia (2.4 grams of dry extract, containing 50% hydroxycitric acid) found that the extract did not increase energy expenditure; it was therefore concluded that this extract showed little potential for the treatment of obesity at this amount.¹⁰ Nonetheless, another double-blind trial found that using the same amount of Garcinia cambogia extract significantly improved the results of a weight-loss diet, even though the amount of food intake was not affected.¹¹