Supplements: Green Coffee Bean Extract

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Green coffee extract may help weight loss but is it worth the risk?

Green Coffee
Green Coffee

Green coffee beans are the seeds of the Coffee fruit.  They merely coffee beans that haven’t been roasted.  When we roast coffee beans to produce drinking coffee, the process reduces the chemical chlorogenic acid level in the coffee beans. Chlorogenic acid is thought to be one of the antioxidants in coffee, and it is believed to have health benefits.   Obviously, green coffee beans have a higher level of chlorogenic acid when compared to roasted coffee beans, and green coffee does not make a good cup of coffee.  Green coffee is another one of the miracle supplements that Dr. Oz has publicized on TV as causing weight loss without the need to exercise.  

Coffee beans, green or roasted, contain two substances believed to help with weight loss.  The beans contain both caffeine and chlorogenic acid.

How it works: Caffeine is thought to decrease appetite and increase fat burning​[1]​.  Chlorogenic acid reportedly slows the breakdown of carbohydrates in the gut.  I will discuss caffeine elsewhere.  Here I want to look at green coffee bean extract (GCE).  

Effectiveness: Many studies have shown that GCE may promote weight loss.  The first study that is often quoted is by Vinson and it was a double-blind placebo trial that looks at using GCE in overweight patients.  At first glance, it would appear that GCE was effective at preventing obesity and possibly losing weight.  Since being published, the article has been retracted.  It should not longer be used as evidence​[2]​.   Another study look at chlorogenic acid supplemented coffee and its effect on weight loss and glucose levels.  The researchers found that the group lost 5.4 kgs in the test group versus 1.7 Kgs in the control group.   They concluded that chlorogenic acid enriched coffee appears to have a significant reduction in the absorption and utilization of glucose from the diet​[3]​.  A meta-analysis review concluded that GCE might assist in weight loss but more research is needed​[4]​.  

Another interesting study shows that GCE increased lipid release and fat loss in patient’s chlorogenic acids​[5]​.  That study was paid for by a supplement company that produces a GCE supplement  It is interesting and could use further research.  

A review of the website that taught the benefit of GCE includes claims that it might help with blood pressure, obesity, dementia, diabetes type 2, and Alzheimer’s.  A review by Web MD concluded that although there might be evidence to suggest that it might be helpful for weight loss and blood pressure, there is insufficient evidence to support such claims.  Clearly, more research is needed​[6]​.

If Web MD is not enough, a review by Mullin, looked at all the research as a whole and concluded that although GCE might have a modest on increasing or maintain weight loss but that the risk is not worth the benefit.  He recommended that we instead drink a lighter roast coffee if we want more chlorogenic acid in our diet​[7]​.   

Side effects:  The following list is in alphabetical order.  It is a pressure scary list.  * denotes a more common side effect.  

  1. Agitation
  2. Anxiety
  3. Calcium deficiencies
  4. Depression
  5. Diarrhea *
  6. Fatigue
  7. Flushing
  8. Glaucoma
  9. Headache
  10. Insomnia
  11. Increased blood pressure *
  12. Increased cholesterol
  13. Increased respiratory rate
  14. Increased heart rate *
  15. Irregular heartbeats
  16. Irritability
  17. Magnesium depletion
  18. Muscle tension
  19. Nausea
  20. Nervousness
  21. Restlessness
  22. Ringing in the ears (tinnitus)
  23. Trouble concentrating
  24. Upset Stomach
  25. Vomiting
  26. Worsened bleeding disorders

The bottom line: Green coffee bean extract may increase weight loss in the short term, but it is not worth the risk.  We do not know the long term side effects.  As with most supplements, you have to remember that many of the studies were industry sponsored and they have vested interest in ensuring that the study sells more of their product.  

The results are back by another study. It was performed on rats. The study confirmed that low dose GCE has a beneficial effect on body weight and lowers total serum cholesterol, triglyceride, LDL, and TNF-α levels in high-fat diet-induced obese rats. The findings strengthen the scientific evidence on the property of GCE in the management of obesity and hyperlipidemia​[8]​.


  1. [1]
    D. Icken et al., “Caffeine intake is related to successful weight loss maintenance,” Eur J Clin Nutr, pp. 532–534, Nov. 2015, doi: 10.1038/ejcn.2015.183. [Online]. Available:
  2. [2]
    J. Vinson, M. V. Nagendran, and B. R. Burnham, “Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects,” DMSO, p. 21, Jan. 2012, doi: 10.2147/dmso.s27665. [Online]. Available:
  3. [3]
    E. Thom, “The Effect of Chlorogenic Acid Enriched Coffee on Glucose Absorption in Healthy Volunteers and Its Effect on Body Mass When Used Long-term in Overweight and Obese People,” J Int Med Res, pp. 900–908, Nov. 2007, doi: 10.1177/147323000703500620. [Online]. Available:
  4. [4]
    I. Onakpoya, R. Terry, and E. Ernst, “The Use of Green Coffee Extract as a Weight Loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials,” Gastroenterology Research and Practice, pp. 1–6, 2011, doi: 10.1155/2011/382852. [Online]. Available:
  5. [5]
    J. Flanagan, A. Bily, Y. Rolland, and M. Roller, “Lipolytic Activity of Svetol®, a Decaffeinated Green Coffee Bean Extract,” Phytother. Res., pp. 946–948, Dec. 2013, doi: 10.1002/ptr.5085. [Online]. Available:
  6. [6]
    “WEB MD,” Green Coffee, 13-Oct-2016. [Online]. Available: [Accessed: 17-Apr-2020]
  7. [7]
    G. E. Mullin, “Supplements for Weight Loss,” Nutr Clin Pract, pp. 311–312, Mar. 2015, doi: 10.1177/0884533615572655. [Online]. Available:
  8. [8]
    C. Ilmiawati, F. Fitri, Z. D. Rofinda, and M. Reza, “Green coffee extract modifies body weight, serum lipids and TNF-α in high-fat diet-induced obese rats,” BMC Res Notes, Apr. 2020, doi: 10.1186/s13104-020-05052-y. [Online]. Available:
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About the Author

I am a family physician who has served in the US Army. In 2016, I found myself overweight, out of shape, and unhealthy, so I made a change to improve my health. This blog is the chronology of my path to better health and what I have learned along the way.

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