Garcinia cambogia is one of the best-selling weight loss supplements of the last decade. It gained most of it’s popularity in 2012, when it was featured on the Dr. Oz show, and quickly became all that people talked about.
What exactly is Garcinia cambogia, though, and how does it work?
Is it an effective weight loss supplement?
More importantly, is it safe and free of side effects?
What is Garcinia cambogia?
Garcinia cambogia, also known as Garcinia gummi-gutta and Malabar tamarind, is a small, pumpkin-shaped, green or yellow tropical fruit which is native to Indonesia.
The rinds of the fruit are traditionally used in cooking, such as in the preparation of curries, mostly in Asian countries.
The skin of the fruit is rich in hydroxycitric acid, also known as HCA, which is structuraly similar to the citric acid found in some citrus fruits and which is thought to help with weight control.
How does Garcinia cambogia work?
Garcinia cambogia is thought to help with weight loss through the action of hydroxycitric acid (HCA). More specifically, HCA is believed to cause weight loss in three ways:
- By competitively inhibiting the enzyme adenosine triphosphatas (ATP) citrate-lyase. This enzyme helps convert carbohydrates into fats, so inhibiting its action means that carbohydrates are used for energy rather than stored as body fat. 
- By increasing the release or availability of serotonin, a neurotransmitter involved in appetite control, thereby leading to appetite suppression. 
- By inhibiting pancreatic alpha amylase and intestinal alpha glucosidase, thereby leading to a reduction in carbohydrate metabolism. 
Does Garcinia cambogia really work?
A number of randomized controlled trials have studied the effects of HCA supplementation on body weight and fat loss with, overall, mixed results.
For example, one study by Roongpisuthipong et al which was carried out on 50 obese women over a 2 month period reported a significant decrease in fat mass in the HCA group (2.4 kg) compared to the control group (1.4 kg). 
Another two studies by Hayamizu et al, one 8 weeks long and the other 12 weeks long, reported significant decreases in visceral, subcutaneous, and total fat areas in the HCA group compared with placebo, but found no significant differences in BMI or body weight. [5, 6]
In contrast, most other studies reported no significant differences in appetite, energy intake or body fat loss between the groups taking HCA and the groups taking placebo. [7, 8, 9, 10, 11]
It’s important to note that most of the studies suffer from a number of methodological issues, including:
- small sample sizes,
- short durations,
- high dropout rates,
- varied HCA dosages and
- varied study durations.
Overall, most studies show no benefit to supplementing with Garcinia cambogia for weight loss and, although some studies report increased weight loss or body fat loss, the size of the effect is quite small and unreliable.
Is Garcinia cambogia safe and free of side effects?
With regards to its safety, supplementation with Garcinia cambogia doesn’t seem to be toxic or dangerous at commonly used doses, at least in the short term. 
It’s important to note that it’s unclear how safe it is in the long term, since the duration of the studies seems to be quite short.
Common side effects reported with daily supplementation include:
- gastrointestinal discomfort, and
- headaches. 
Verdict: should you buy Garcinia cambogia?
Overall, it seems that the cost and potential side effects of supplementing with Garcinia cambogia are not worth the very small and unreliable impact it may have on weight loss.
If you are trying to lose weight, here are a few articles you may find helpful:
10 Weight Loss Tips for Easier & More Successful Dieting
Why You’ve Stopped Losing Weight (and What to Do About It)
5 Reasons Your Fat Loss Diet Sucks (and How to Fix It)
The Secret to Fat Loss: Time to Uncover the Truth