Garcinia Cambogia - is it really a miracle weight loss supplement?

Garcinia Cambogia supplements come with some major claims, but is it really a miracle weight loss supplement?

What is Garcinia Cambogia?

Garcinia Cambogia is the scientific name for an South-East Asian fruit also known as Garcinia gummi-gutta, gambooge, brindleberry, vadakkan puli (northern tamarind), kudampuli (pot tamarind) brindall berry and Malabar Tamarind.

It is a green fruit that turns yellow when ripe, with the active ingredient being found in the rind. Traditionally, Garcinia cambogia has been used for Indian Medicine to treat a wide range of ailments and is also used as a flavouring in many south-eastern dishes.

How is Garcinia Cambogia supposed to help with weight loss?

The active ingredient in Garcinia cambogia extract hydroxycitric acid (HCA) is used as a slimming aid, often in combination with other supplements such as caffeine or green coffee bean extract. HCA is also found in other related garcinia species including indica and atroviridis and has been linked with appetite suppression, supposedly from increased release or availability of serotonin in the brain.

The exact mechanism is not yet known. Companies producing Garcinia cambogia supplements state that their products are 'clinically proven' to enhance fat and weight loss 2-3 times greater than normal. A quick google search of what garcinia cambogia does will quickly lead you to claims that it will reduce belly fat, increase mood, increase lean muscle mass, ease cravings, support digestive function, inhibit production of cholesterol and has no known side effects and much much more.

Truly a miraculous supplement!

What does the research say about Garcinia Cambogia?

Surprisingly, Garcinia cambogia is not a newly discovered supplement - researchers having been studying it's effects on weight loss for over 15 years!! Here is a quick overview of the human research published during this period: A randomised-controlled trial published in the Journal of the American Medical Association in 1998 found no effect on weight loss from HCA supplementation. All 135 participants were placed on a high-fibre, low fat diet (1200kcal/5040kJ per day) and were randomised to either the placebo or 3000mg Garcinia cambogia extract (1500mg HCA) for 12 weeks. There was no difference in weight loss or fat mobilizing effects between the placebo or supplemented group at the end of the study. The authors concluded that their observations did not support a role for Garcinia cambogia as a promotor of weight loss. However these results have been criticised as it is thought that a high-fibre diet may inhibit the absorption of HCA.

One of the articles used as 'clinical proof' is this Randomized controlled trial published in 2000 following 40 obese participants over a 12 week period. The authors found that those consuming a supplement containing a-amylase, inulin and Garcinia cambogia lost 2.3kg more than those taking the placebo. So many limiting factors I don't know where to begin, but considering the fact that the supplement used contained only 300mg of Garcinia cambogia, this is not a strong study to use as 'clinical proof' that the weight loss was purely related to the HCA content. Particularly for companies advising consumption of approximately 1600mg HCA per day on average.

Companies producing Garcinia cambogia extract also link to this 'famous study' that 'clinically proves' that HCA and subsequently their brand of supplement will accelerate your weight and fat losses. This randomized, double-blind, placebo-controlled trial published in 2003 randomised 44 overweight participants with a BMI of 25-35kg/m2 to receive either 1667mg Garcinia cambogia extract (1000mg HCA) daily or the placebo for 12 weeks. During the study participants were placed on diets of 2250kcal for men and 1800kcal for women. It is worth noting that at baseline, there was an average weight difference of 6kg in men and 2kg in women between the placebo and treatment group. There were also large differences between placebo and treatment arm at baseline - particularly for men in regards to total fat area, visceral fat area and subcutaneous fat area. Before the study even began, the men in the Garcinia cambogia group had 116% more total fat than the placebo group - a difference of over 51cm2! This fact confounds the results that those taking the supplement lost 10-15% more fat during the study - limiting how the results can be used in practice.

I like how the author's conclusion that 'It is therefore expected that Garcinia cambogia may be useful for the prevention and reduction of accumulation of visceral fat ' has been translated to say something along the lines of Garcinia cambogia will help you burn fat. Slight misinterpretation perhaps?!

A systematic review and meta-analysis published in 2011 critiqued all published studies on Garcinia extracts, hydroxycitrate, fat and weight loss. All of the 12 randomised controlled trials (RCTs) included had methodological weaknesses. The meta-analysis determined that while there was a borderline statistically significant difference in body weight between HCA and placebo groups, the actual size of this effect was small consisting of a loss of 0.88kg or 1% difference in body weight loss. This was considered too small for clinical relevance and was no longer statistically significant when only rigorous RCTs were included in the meta-analysis. All but two studies incorporated some form of dietary control ranging between 1000kcal-3009kcal which may have influenced results.

In 2011 a ten-week RCT published in the Nutrition Journal randomised 86 overweight participants to establish the effectiveness of 2000mg Garcinia cambogia (60% HCA) and Glycine max in promoting weight loss and lowering cholesterol. Neither supplement promoted weight loss or lowered cholesterol when participants continued their normal diet. A review published in Critical Reviews in Food Science and Nutrition in 2012 evaluated the safety and toxicity of Garcinia cambogia extracts particularly in relation to weight management. Of the 15 studies suitable for inclusion, only 6 found weight loss significantly higher in the intervention group compared to the placebo, with most participants receiving lifestyle advice regarding a low-fat, low energy diet and increased physical activity. No studies examined whether the supplement had an effect on weight or fat-loss beyond 12 weeks. They concluded that there is little evidence to support the effectiveness of Garcinia cambogia and that results of studies supporting the use of Garcinia cambogia should be interpreted with caution due to their small sample sizes and short duration.

My advice?

While there is always potential that future trials may show more conclusive results, the evidence we have available in this current day and age does not support the claims that Garcinia cambogia is a weight loss miracle supplement. Considering that a months' supply can cost anything from £18-£40 per month and more, my advice is to save your money and maybe take nutritional advice and supplement endorsements from Dr Oz with a (large) pinch of salt.

Gemma

References

S Heymsfield, D Allison, J Vasselli, A Pietrobelli, D Greenfield, C Nunez (1998) Garcinia cambogia (Hydroxycitric Acid) as a Potential Antiobesity Agent. A Randomized Controlled Trial. JAMA 280(18):1596-1600 PDF

E Thom (2000) A Randomized, Double-blind, Placebo-controlled Trial of a New Weight-reducing Agent of Natural Origin. The Journal of International Medical Research 28:229-233 PDF
K Hayamizu, Y Ishii, I Kaneko, M Shen, Y Okuhara, N Shigematsu, H Tomi, M Furuse, G Yoshino, H Shimasaki (2003) Effects of Garcinia cambogia (Hydroxycitric Acid) on Visceral Fat Accumulation: A Double-Blind, Randomized Placebo-Controlled Trial. Current Therapeutic Research Vol 64(8)551-567 PDF
Garcinia Cambogia extract 90045-23-1 National Cancer Institute 2004 PDF
Onakpoya et al (2011) The Use of Garcinia Extract (Hydroxycitric Acid) as a Weight loss Supplement: A systematic review and meta-analysis of Randomised Clinical Trials. Journal of Obesity vol. 2011, Article ID 509038, 9 pages, 2011. doi:10.1155/2011/509038 PDF
JE Kim, SM J, KH Park, WS Lee, TS Jeong, RA McGregor, MS Choi (2011) Does Glycine max leaves or Garcinia Cambogia promote weight-loss or lower plasma cholesterol in overweight individuals: a randomized control trial Nutrition Journal 10:94 PDF
F Marquez, N Babio, M Bullo, J Salas-Salvado (2012) Evaluation of the Safety and Efficacy of Hydroxycitric Acid or Garcinia cambogia Extracts in Humans Critical Reviews in Food Science and Nutrition, 52:585–594

Gemma

General Nutrition, InfographicsGemma Sampson12 September 2016