Hydroxycitric acid (HCA) is a unique nutraceutical ingredient that is similar in structure to the common citric acid. It is found in large amounts in the pericarp (fruit rind) of the Garcinia cambogia tree. Native to India, these fruit rinds have been used in cooking, primarily to make the meals feel "more filling". This ingredient has been made popular by the tradename CitriMax®, which is a calcium salt of HCA standardized to 50 or 60% HCA. The major use of HCA is in weight reducing programs. It serves as an appetite suppressant and reduces productions of cholesterol and other lipids.

HCA acts as an inhibitor in the enzymatic reaction that allows the body to release acetyl-CoA from citrate to make and store fats. This inhibition subsequently effects the rate of glycolysis (conversion of glucose into energy) and shifts it to the storage form of sugar (glycogen). When glycogen is produced and stored, the glucoreceptors in the liver induce the feeling of fullness. When this is induced prior to a meal, less food will allow the person to feel full, and carbohydrate cravings are reduced.

HCA is often added to supplements for weight reduction and sugar control. It is quite frequently present with chromium, vanadium and other sugar controlling nutritional ingredients. HCA is extremely safe and well tolerated for long-term use.