The active ingredient extracted from the garcinia cambogia fruit, similar to an orange. It is commonly used as an appetite suppressant.

Hydrocitric acid or HCA is a "lipogenesis inhibitor," which means that it slows down the production of fat from the metabolism of carbohydrates and proteins. This means that more calories are burned as energy and less are turned into stored fat.

Studies on animals and humans have shown that HCA can suppress fat production and reduce appetite.