Grean coffee bean weight loss benefits overstated.
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Grean coffee bean weight loss benefits overstated.

The green coffee bean supplement industry, backed most famously by Dr. Oz, has been criticized for its lack of evidence and oversight. Now a new study in the Journal of Agricultural and Food Chemistry casts fresh doubt on a key ingredient in green coffee beans as a "miracle" weight-loss product.

The study specifically looked at chlorogenic acid (CGA), one of several compounds called polyphenols found in coffee which is most often cited for its supposed weight-burning properties. Prior studies have suggested that as a group, coffee's polyphenols offer health benefits, such as reducing blood pressure. And CGA, for its part, was shown in a 2010 paper to have anti-obesity properties in mice.

Vance Matthews at the Western Australian Institute for Medical Research and Kevin Croft at the University of Western Australia wanted to find out what happened when mice were given comparatively higher doses of CGA – more in the range of the equivalent of five daily cups of coffee for a person, rather than one to three as in previous studies.

The researchers fed two sets of mice a high-fat diet and administered CGA to one of the groups. The supplemented mice ended up just as obese as the other gluttonous mice. Adding insult to injury, the CGA-supplemented mice also had a buildup of fat in their livers and showed signs of developing type 2 diabetes.

Although CGA at higher doses does not seem to protect against weight gain, the polyphenol on its own at lower doses, and in concert with other polyphenols, might still have some worth. For example, a study by Croft has hinted that CGA lowers blood pressure in humans (rodents, too, for the record). Coffee consumption, it appears, is a healthy choice overall when not done in excess, and CGA supplementation may have its uses, though weight loss claims are questionable. The takeaway, Matthews said: "Simply drink coffee in moderation."