Following his frequent appearances on the Oprah Winfrey show and later starting his own show, Dr. Oz grew to become America’s most famous and socially influential physician. Like his mentor’s Oprah Effect, his show has birthed the Oz Effect, surging sales of featured products. Garcinia cambogia’s popularity as a weight loss aid soared after it was featured on the show in 2012.
For his claims, Dr. Oz was summoned by Congress and even removed the video from his YouTube channel. Garcinia cambogia has however continued to be widely used as a fat burner over the last ten years. I took a look at the studies around it to determine if it's as good as proponents claim it is. Read on.
Key Points
What is Garcinia Cambogia?
Also referred to as Malabar tamarind or brindle berry, garcinia cambogia is a small green or yellow pumpkin-shaped fruit native to South Asia and South-East Asia. The scientific community has since changed its name to garcinia gummi-gutta. But given the enormous marketing it has enjoyed in recent years, garcinia cambogia is the name the average person will be most familiar with and is what I will stick to throughout this text.
It is in the fruit’s peel that you find the active ingredient used in weight loss supplements — hydroxycitric acid (HCA). It is the efficacy of HCA that studies focus on. It is believed this acid promotes weight reduction by blocking ATP-citrate lyase thus inhibiting fat production.
Studies on Garcinia Cambogia
Mega influencers like Dr. Oz may have been a key catalyst for the global wave of garcinia cambogia’s popularity. But garcinia cambogia has a long history of use. In modern research, there are animal experiments on HCA going as far back as 1977. I’ll start off with a look at two multi-study analyses that document garcinia cambogia’s weight loss abilities.
Multi-Study Reviews
A 2014 review of nine randomized clinical trials found there was a significant reduction in body weight among subjects placed on HCA when compared to those on the placebo. In 2015, a literature review of 21 studies concluded that garcinia cambogia supplementation had a positive effect on weight loss, appetite suppression, percentage of body fat and glucose levels reduction.
Multi-study reviews are a great way to develop a summary conclusion since they somewhat cancel out the biases present in smaller, narrower individual studies.
The Fat Loss Question
Fat reduction is really where garcinia cambogia’s weight loss power is believed to lie. And there are multiple studies around this.
In one published in 2003, 39 obese persons were randomly assigned to either a placebo or 1,000 mg HCA per day for 12 weeks. The HCA group showed significant reduction in abdominal and total fat. There was however no material difference in body weight or BMI between the two groups, something that would perhaps place a caveat on garcinia cambogia’s impact on overall weight loss.
Another 2003 study looked at six unfit women that ingested either a placebo or 250 mg HCA for five days then participated in endurance exercises. It found that those on HCA supplementation had faster fat metabolism and increased exercise endurance. No mention of weight loss here but once again, a strong case for fat loss.
In 2005, an 8-week study involving 82 obese subjects found that individuals placed on HCA (2,800 mg). This study came to a broader conclusion. The HCA group exhibited much greater reduction in appetite, body weight, BMI and LDL cholesterol (i.e. bad cholesterol) as well as an increase in HDL cholesterol (good cholesterol) compared to the placebo group.
Studies Casting Doubt on HCA
A 2004 study involved 21 healthy weight or moderately obese individuals placed on either a placebo, 500 mg HCA or a combination of 500 mg HCA and 3,000 mg medium-chain triglycerides (MCT) for two weeks. It found no differences in satiety and energy intake between the three groups. This study confirmed the findings of a 2-week study published in 2001 involving 11 overweight male subjects as well as a 12-week 2000 study of 89 mildly overweight women.
A key point to note here is that these studies debunked HCA’s ability to increase satiety and not necessarily weight loss as a whole.
Side Effects and Safe Dosage
HCA has been reported to cause skin rashes, headaches, nausea, gastrointestinal discomfort, mania, respiratory problems and liver damage. There is an extremely rare but possible likelihood of testes shrinkage and serotonin toxicity.
Each of the studies I mentioned found no side effects from the use of garcinia cambogia based on the amounts used. That was irrespective of whether they found it effective for weight loss. We can conclude that doses of up to 2,800 mg HCA per day are safe.
To their credit, fat burners containing garcinia cambogia usually have it way below this safety ceiling — sometimes under 100 mg HCA. While amounts vary considerably between brands, the overwhelming majority are below 1,500 mg HCA per day.
Wrapping Up
Garcinia cambogia and HCA are so deep-rooted in the weight loss supplement industry that I think for its most passionate users, what the science says will not matter much. There is far from unanimity that it works but there are strong indications on at least one front — that it may support the reduction of body fat and inhibits fat production.
A key drawback of current studies is the scarcity of longer term (90+ days) studies. I think the more such studies are published the greater the likelihood of a convergence of views on garcinia cambogia’s weight loss prowess. Even if you do choose to use garcinia cambogia, it cannot be your sole or primary supplement. You are better off combining it with products and natural compounds with a more solid reputation for weight loss.