While diet should always come first, some people look for a quick fix and turn to various weight loss supplements.
One of the most popular of these ‘fat-burning’ options is Garcinia Cambogia.
Known as one of the many (so-called) “miracle” products endorsed by Dr. Oz, this herbal supplement is a multi-million dollar industry.
Although some claim it helps us to lose weight safely, others view it as nothing more than snake oil.
This article provides the facts about garcinia cambogia extract, including the benefits, drawbacks and possible risks according to independent studies.
What is Garcinia Cambogia?
With the botanical name of ‘garcinia gummi-gutta,’ garcinia cambogia is an incredibly sour tropical fruit which is native to Indonesia.
People also refer to the fruit as ‘brindleberry’ and ‘malabar tamarind’.
Garcinia cambogia looks somewhat similar to a pumpkin, but it is pale green in color;
The size can vary, and it can be as small as a persimmon or as big as a grapefruit.
Manufacturers use an extract from the peel of the fruit to make the “natural” weight loss supplement.
This peel contains hydroxycitric acid (HCA), which is the main active ingredient in the supplements.
Various studies show this compound to have both positive and negative biological impacts on health.
The predominant use of garcinia cambogia extract is for weight loss.
However, studies also link it to better cholesterol and blood sugar regulation among other benefits.
Also, it is a favorite food condiment well-known for its sour taste in Indian and Thai cuisine.
How Does Garcinia Cambogia Work?
There are several theories on how garcinia cambogia may cause weight loss, ranging from appetite suppression to “blocking” fat accumulation.
First of all, the research is very mixed, but here are some results from studies looking into the extract;
The net effect of this is a decreased blood glucose (and subsequent insulin) response after food.
As a result, there is an indirect effect on appetite suppression.
This happens because larger spikes and falls in blood glucose and insulin levels stimulate hunger and food cravings.
Appetite and Cravings
Several studies analyze the impact of HCA—the active ingredient of garcinia cambogia—on appetite suppression.
First of all, animal studies show the extract exerts influence on the brain cortex to down-regulate appetite.
Despite limited data on human participants, several recent randomized controlled trials suggest a positive impact on weight loss.
These double-blind, placebo-controlled studies found that appetite suppression is a common observation (9).
The effect of garcinia cambogia on appetite suppression may be due to the compound raising serotonin levels in the brain (10).
Blocking Fat Production
Another health claim behind garcinia cambogia extract is that it “blocks” fat production.
So, how does this work?
HCA completely blocks an enzyme called adenosine triphosphate citrate lyase.
I know that’s a bit of a mouthful, so we can call it ATP citrate lyase for short.
ATP citrate lyase is an essential enzyme for the synthesis of fatty acids.
In particular, it plays a significant role in de novo lipogenesis (basically the conversion of carbohydrate into fat stores).
Does Garcinia Cambogia Extract Cause Weight Loss?
Knowing how the supplement supposedly works is helpful, but does it actually cause weight loss?
And if so, how much?
Here are some findings from a variety of human studies;
- A 16-week randomized controlled trial involving 44 participants resulted in “significantly reduced visceral, subcutaneous, and total fat areas compared with the placebo group” (20).
- Human studies—both in ordinary untrained people and athletes—show that HCA supplementation slightly increases fat oxidation (21, 22).
- An 8-week randomized controlled trial suggests weight loss benefits, with participants BMI decreasing by 5-6% versus placebo (23).
If you were starting to think that garcinia cambogia sounds good, then there are also some negative findings.
These studies appear to contradict the positive outcomes;
- A randomized controlled 10-week study of eighty-six overweight subjects had no effect on weight loss compared to placebo (24).
- In a randomized, controlled study analyzing sedentary male participants, HCA did not alter the rate of fat oxidation. This was equally ineffective during exercise and when resting (25).
- A further 12-week RCT of 135 subjects found that garcinia cambogia “failed to produce significant weight loss beyond that observed with placebo” (26).
Meta-Analysis of Randomized, Controlled Trials
There is a relatively large-scale meta-analysis from 2011 which analyzes prior RCTs on garcinia cambogia (27).
The study provides an easy visual demonstration on the weight loss outcomes;
As we can see, nine RCTs show supplementation is slightly more effective compared to placebo.
Commenting on the study, the researchers noted that garcinia cambogia extract induces short-term weight loss.
However, they added that “the magnitude of this effect is small” and “its clinical relevance seems questionable.”
However, any compound that can influence hormones in the body is also powerful enough to have side effects.
- Brain fog
- Digestive issues
- Lower immunity
- Stomach discomfort
However, only a small proportion of people using garcinia cambogia experience these.
Serious Adverse Effects
Although rare, there are also records of severe side effects. These include liver damage and serotonin toxicity;
The lady in question became progressively worse and eventually needed a liver transplant due to liver failure.
There is no definite proof this was due to the supplement she was taking.
However, researchers conducted an investigation which found that “garcinia cambogia was the most probable” cause of the liver failure (30).
Garcinia cambogia can help increase the amount of serotonin in the body.
A lady who took combination the supplement was also taking serotonin reuptake inhibitor (SSRIs) prescription drugs.
As a result, she suffered from serotonin toxicity and subsequently developed hypertension and tachycardia, requiring emergency treatment (31).
This story is a good reminder to be aware of any possible drug interactions when taking any supplements.
If you are taking prescription medicines, always be careful and check with your physician before commencing supplementation.
Is Garcinia Cambogia Extract Safe?
Despite the fact these mild and severe side effects are very dangerous, they are also very rare.
The vast majority of people using the supplement have no adverse symptoms.
However, in truth, any drug or herbal supplement can have side effects.
It’s also worth remembering that herbal supplements do not need FDA approval before going on sale.
As a result, many supplements on the market are not proven to be safe.
On the other hand, no safety trials last longer than 12 weeks, so the long-term safety profile is unknown (35).
Non-Weight Loss Benefits
Aside from weight loss, garcinia cambodia extract has some other documented benefits;
- Improved cholesterol profile: A study on obese participants found that garcinia cambogia “significantly reduces triglyceride levels.” However, other health markers such as LDL and HDL remained the same. Animal studies also show the same triglyceride-lowering effect (36, 37, 38).
- Lowers blood glucose levels: Various studies show that groups supplementing with garcinia cambogia have lower blood sugar spikes after eating compared to placebo (39, 40).
- Normalizes leptin levels: People using garcinia cambogia experience a reduction in leptin levels. High leptin in the blood is associated with cardiovascular risk (27, 41, 42).
- Reduces inflammation: Studies suggest that HCA can improve antioxidant status and mitochondrial function. As a result, it helps to reduce inflammation and oxidative damage (43, 44, 45, 46).
The Verdict: Weight Loss or Worthless?
Looking at the science behind garcinia cambogia, it most likely helps to lose a minimal amount of weight.
On the other hand, it does not guarantee safe and effective weight loss – nor is it necessary to take diet supplements.
The single best way to lose weight is through a healthy diet that prioritizes nutrient-dense foods.
Whether you have a dietary preference for keto, paleo, or any whole food-based diet, eating real food is the optimal weight loss path.
Personally, I believe people over-think nutrition far too much these days. Humans existed for millions of years without magic diet pills to lose weight.
But back then, we had what most people don’t have today – a healthy lifestyle full of nutritious food, exercise, and adequate sleep.
To get started losing weight with real food, see this article on weight loss.