If only weight loss were as easy as popping a dietary supplement that’s natural and safe. Garcinia cambogia has long been touted as that panacea. This tropical fruit, grown in Africa and Asia, contains hydroxycitric acid (HCA), a long-time ingredient in many weight loss formulas, which was first identified in the late 1960s. Some lab and animal research suggests that the HCA (and possibly other compounds) in garcinia may help promote weight loss by suppressing appetite and inhibiting the storage of excess calories from carbohydrates as fat.
But there has been little good research in humans on garcinia’s effect on weight. Moreover, HCA has an effect only when people eat meals high in carbs (not fat), and it is short-acting, so it has to be taken about an hour before eating. Even then, the effect may not be significant.
The Natural Standard database (now called Natural Medicines), which reviews evidence about supplements and other alternative and complementary products, concluded that the evidence about garcinia and weight is conflicting and unclear. Similarly, the National Center for Complementary and Integrative Medicine (part of the National Institutes of Health) found no convincing evidence that garcinia promotes weight loss.
A meta-analysis of clinical trials, published in the Journal of Obesity in 2011, found that garcinia extract produced only very small changes in weight. But the researchers noted that the studies reviewed were short (none longer than 12 weeks), small, and rife with methodological problems. So it’s unclear whether any weight loss was clinically relevant. Plus the analysis found side effects, including nausea and headaches.
In a 2014 study in Phytotherapy Research, researchers looked at 43 overweight and obese women who took garcinia extract or a placebo daily for two months. There was no significant change in weight, body fat, or waist-to-hip ratio. There was also no change in leptin, a hormone that inhibits hunger.
Risks of garcinia
What’s most concerning about garcinia is evidence from human case reports as well as animal studies showing adverse effects in the liver. For instance, an animal study in the World Journal of Gastroenterology in 2013 found that garcinia can induce liver damage by increasing inflammation, free radical formation, and the formation of excess connective tissue, indicating that some pathological process was occurring.
In the Annals of Hepatology in 2016, a case report focused on a 52-year-old woman who took garcinia for weight loss for almost a month who was hospitalized with acute liver failure that required a liver transplant. The researchers concluded that the supplement was most likely the culprit. Similarly, in another case report in 2016, published in the World Journal of Gastroenterology, a 34-year-old man who had been taking garcinia for five months developed liver failure and needed a liver transplant.
A different type of adverse effect was described in a 2014 case report in the Journal of Medical Toxicology, which looked at a 35-year-old woman who went to the emergency room because of profuse sweating, difficulty speaking, hypertension, and a rapid heart rate. She had been taking garcinia as well as a type of antidepressant (a selective serotonin reuptake inhibitor, or SSRI) that boosts levels of serotonin, a key brain chemical. The doctors diagnosed her with serotonin toxicity and attributed it to an interaction between the antidepressant the HCA in garcinia, which can also increase serotonin levels.
Bottom line: Given the potential serious risks and the lack of evidence of benefits, we strongly recommend avoiding garcinia and any diet formulas containing it.
Also see What's in Your Diet Pills?