Garcinia cambogia is a small fruit that resembles a miniature pumpkin. It is indigenous to India and parts of Asia, and an extract from its fruit and rind is popular in many natural weight loss products. The extract is hydroxycitric acid (HCA), claimed to suppress appetite and enhance fat-burning. Animal research supports these claims, but subsequent human trials have been equivocal.

The theory behind garcinia cambogia is that HCA inhibits an enzyme called citrate lyase that helps turns excess carbohydrates into fat. By inhibiting this enzyme, it is believed the body instead boosts carbohydrate oxidation, or simply put, burns the extra carbs. In extensive animal studies, garcinia cambogia was found to reduce food intake by suppressing appetite, as well as to decrease body fat. Human trials have been less clear. While some double-blind studies using garcinia cambogia and a placebo showed the HCA group as doubling or tripling weight loss over a 12-week period as compared to the control group, other studies showed a less promising result.

The Journal of the American Medical Association (JAMA) published such a study that used a daily dose of 1500mg of HCA over a 12-week period on healthy, overweight adults. At the end of the study, the group receiving garcinia cambogia did not see statistically different weight loss from the control group. However, this study has been criticized by some, with the claim that the high-fiber diet used in the trial likely interfered with the body’s ability to absorb HCA. Unfortunately, the study did not test the subjects to see whether HCA was found in the cells where it becomes active.

Garcinia cambogia reportedly does not have any known adverse effects in healthy adults, but there are some people who are advised not to take it. According to experts, this includes children, pregnant and lactating women, those diagnosed with diabetes mellitus, and people with Alzheimer’s or other forms of dementia disease. In the case of Alzheimer’s patients, it is thought HCA might form acetylcholine in the brain, while diabetics could be affected by HCA’s tendency to lower blood sugar. Conversely, in healthy adults this latter effect can purportedly curb cravings for sweets and carbohydrates.

Garcinia cambogia is usually sold in capsule form, standardized to include a percentage of HCA, the active ingredient. Only brands standardized to 50% or greater HCA are generally recommended. For maximum effect, the daily dose is divided in three parts, taking one or more capsules 30-60 minutes before breakfast, lunch, and dinner.

Some manufacturers claim garcinia cambogia must build up in the system before the full benefits can be realized. It has also been suggested that HCA might help people who have already attained their ideal weight to maintain it. The Food and Drug Administration (FDA) does not regulate garcinia cambogia. People who are considering augmenting a healthy diet and exercise regimen with herbal aids like HCA should see their physicians for personalized advice.