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Home » Green coffee beans and weight loss–another dumb myth

Green coffee beans and weight loss–another dumb myth

If you were a fan of the Dr. Oz show, you might have heard about his passionate support of green coffee beans, which are just unroasted coffee beans instead of the roasted ones we enjoy in a big mug, for losing weight. In America, weight loss pseudoscience, especially those who claim it’s “easy”, is an obsession, especially since the country is experiencing an obesity epidemic.

Sadly, Americans are always seeking easy, simple, but effective ways to lose weight that don’t require them to change any behavior at all. In other words, let us eat our Big Macs and never exercise while taking a miracle pill, which makes us maintain a perfect Body Mass Index. If that existed, someone would make more money than the next iPhone.

But let’s focus on those green coffee beans.

bunch of green coffee beans
Photo by Maksim Goncharenok on

The myth of the green coffee beans

The belief that green coffee beans had an effect on weight loss resulted from a 2012 study that touted the “efficacy of green coffee extract in weight loss.” This led to the next big thing in weight loss, which was heavily promoted by Dr. Mehmet Oz. Dr. Oz claimed that “(y)ou may think magic is make-believe, but this little bean has scientists saying they found the magic weight-loss for every body type.” Really?

As with most studies that seem to be the basis of these kinds of overblown claims, time to look at the actual paper. Scott Gavura, a research pharmacist who pens a blog called Science-Based Pharmacy, wrote an article on Science-Based Medicine skeptically analyzing this paper about green coffee beans.

Combining my observations, with Gavura’s, here are some of the major negative points about the article

  • The study only involved 16 patients. A good clinical trial requires numbers that are adequate to gain some level of statistical significance, and 16 isn’t going to cut it. How about several hundred, with adequate controls, and information about any confounding data that may have an influence over the results?
  • “This study was never registered at And there’s no evidence provided that a research ethics board ever reviewed the protocol. I find it hard to believe that any investigator would undertake a clinical trial of an unproven supplement without obtaining prior ethics approval – but that seems to be the case.”
  • The green coffee study was published in Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy, which does not have an impact factor yet, probably because it’s a new journal. Other journals by Dove Press, the publisher of the journal, have impact factors between 1-3, at the very low end of the scale.
  • Even though the journal claims to be peer-reviewed, the time period from submission to editorial decision was 12 days which means the review was “cursory”. I’ve criticized these types of open-access journals as being of inconsistent quality, and obviously a “clinical trial” that includes only 16 patients.
  • None of the authors were clinicians or experts in the field.
  • The authors claimed that the study was double-blinded, but because of the way the study was constructed it was not blinded to either the patient or the clinician.

An important point to remember is that this is a primary study, and no one has repeated the study, let alone give us confirming data.  A systematic review of the research into green coffee beans and weight loss led the authors to conclude that ” the studies are all of poor methodological quality. More rigorous trials are needed to assess the usefulness of GCE as a weight loss tool.” There are still no clinical trials that have been registered to study the effect of green coffee beans on weight loss. So, don’t hold your breath for the “more rigorous trials.”

But there’s more to this story. The blog RetractionWatch took a closer look at issues surrounding the green coffee bean study. They explained that the US Federal Trade Commission (FTC) looked into the marketing of green coffee beans for weight loss, and published this statement:

The FTC complaint alleges the study was so hopelessly flawed that no reliable conclusions could be drawn from it. The flawed study, which purported to show that the product causes “substantial weight and fat loss,” was later touted on The Dr. Oz Show.

The FTC’s settlement with Applied Food Sciences, Inc. (AFS), which sells a green coffee ingredient used in dietary supplements and foods, requires the company to pay $3.5 million, and to have scientific substantiation for any future weight-loss claims it makes, including at least two adequate and well-controlled human clinical tests.

“Applied Food Sciences knew or should have known that this botched study didn’t prove anything,” said Jessica Rich, Director of the FTC’s Bureau of Consumer Protection. “In publicizing the results, it helped fuel the green coffee phenomenon.”

The FTC has some rather harsh remarks about the study itself:

According to the FTC’s complaint, in 2010, Austin, Texas-based AFS paid researchers in India to conduct a clinical trial on overweight adults to test whether Green Coffee Antioxidant (GCA), a dietary supplement containing green coffee extract, reduced body weight and body fat.

The FTC charges that the study’s lead investigator repeatedly altered the weights and other key measurements of the subjects, changed the length of the trial, and misstated which subjects were taking the placebo or GCA during the trial. When the lead investigator was unable to get the study published, the FTC says that AFS hired researchers Joe Vinson and Bryan Burnham at the University of Scranton to rewrite it. Despite receiving conflicting data, Vinson, Burnham, and AFS never verified the authenticity of the information used in the study, according to the complaint.

Wait! What?

The lead researchers didn’t even bother to verify the authenticity of the data. RetractionWatch said, “We’ve asked Vinson whether he and Burnham ever verified the data, and The Dr. Oz Show for comment, and will update with anything we learn.” I’m not holding my breath.

But if you’re still holding out hope that your bottle of green coffee beans is going to make you lose 50 lbs, here’s one more thing–the study was recently retracted, because “The sponsors of the study cannot assure the validity of the data so we, Joe Vinson and Bryan Burnham, are retracting the paper.”

Weight loss is important, it’s probably a major risk factor for some cancers. Weight loss is rather simple, at least mathematically. In general, the average calories burned have to exceed the average calories consumed. Eat less. Burn more. Your choice. If you’re looking for a miracle weight loss, other than the mythical placebo effect (you think it’s going to work so maybe you eat less or walk more, who knows), it’s not going to do anything for you. Walk a couple of miles. Quit eating those potato chips. That’s my expert recommendation!


Michael Simpson

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