Hey Doc, Can These Dietary Extracts Help Me Lose Weight?

  • According to a certain doctor on television, all you need to lose weight is a dietary supplement containing the extract of one of these three ingredients: green coffee bean, raspberry or green tea. As soon as a recommendation is made, everyone floods the market looking for that miracle weight loss pill. On television, you’ll hear testimonies that offer nothing but anecdotal evidence. Instead of believing everything you hear, you might want to take a look at the actual science behind some of these claims.


    Green coffee bean extract is one of the “nutraceuticals” being promoted. One research group examined 16 overweight individuals for 22 weeks. Without significantly changing their diet, the people taking green coffee bean extract lost an average of 8kg (approx.16 pounds).1 Is this evidence significant enough to tell the entire world that green coffee bean extract is a miracle weight loss cure? Hardly; the sample size was too small to give this study any credibility. Besides, the weight loss was marginal at best. Come on, 16 pounds plus or minus a few pounds in 4 months. That’s hardly a miracle.

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    Miraculous weight loss has also been associated with raspberry ketone extracts. Some scientists have fed mice high fat diets and raspberry ketones. The mice became obese and the raspberry ketones supposedly helped them lose weight. The raspberry ketones might have also prevented some weight gain in the mice as well.2 Another animal study also confirms the possibility of raspberry ketone extract altering fat metabolism in a way that would prevent or treat obesity.3 Interestingly, both of these studies are from countries in Asia where nutraceuticals have been a source of speculation and income.


    To their credit, one group of scientists in Asia put together a good study to evaluate whether or not green tea extract caused weight loss in a group of obese women. After 12 weeks, no significant weight loss was noticed; therefore, the theory that green tea extract helps people lose weight is false.4  


    In fact, a well designed a randomized, double-blinded, controlled study on a large group of obese humans would probably discredit any of the claims that we see on television about these “nutraceutical” extracts. Then certain doctors would have to eat their words about miracle cures for weight loss. But unfortunately, the people selling these products are the only ones really benefiting from green coffee bean extract, raspberry ketone extract and green tea extract. Because these products are dietary supplements, the lack of government regulation and oversight leaves society vulnerable hype and false statements. 


    Watching television doctors reminds me of the medicine men from old days that rode into town on their wagon and sold snake oil. Eventually, this wagon full of falsely based hope that dietary extracts represent some type of miracle cure for obesity will leave town with a saddlebag full of cash.


    1. Diabetes Metab Syndr Obes. 2012;5:21-7

        2. Life Sci. 2005 May 27;77(2):194-204

  •     3. Planta Med. 2010 Oct;76(15):1654-8.

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        4. Clin Nutr. 2008 Jun;27(3):363-70.


Published On: April 29, 2013