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Home » Weight loss scams – raspberry ketones and green coffee beans

Weight loss scams – raspberry ketones and green coffee beans

Last updated on September 2nd, 2019 at 02:36 pm

Next up, weight-loss scams (see Note 1) – you know all about them. Take one supplement and suddenly you lose kilograms of weight while eating burgers and fries while watching TV. They often appear in email spam, the Dr. Oz show, or a random Google search.

These weight loss scams, especially those who claim it’s “easy”, are an obsession with Americans (though it’s not unique to this country), especially since the USA is experiencing an obesity epidemic. 

Americans (maybe everyone else) 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 and maintain a perfect Body Mass Index. If that existed, whoever sold it would be richer than Bill Gates

Two pseudoscientific weight-loss scams have been hitting the public consciousness – raspberry ketones and green coffee beans. Dr. Oz, who despite a solid education in science-based medicine has been promoting everything from homeopathy to Joe Mercola‘s various lunatic cures, has been pushing both of these weight loss scams to his audience in the past. 

But it’s not just him, you can find ads all over the internet for them. I won’t link to them, because why should I send those quacks any clicks?

However, we’re here to answer the most important question – are these weight loss scams really scams? Is there anything there? 

Raspberries are delicious. They don’t make you lose weight. Photo by Paul Shore on Unsplash.

Weight loss scams – raspberry ketones

Let’s start with the raspberry ketones. It is essentially a phenolic compound produced by the raspberry that gives the raspberry the aroma that we recognize. However, because it is produced in such small amounts by the plant, it must be synthesized to be used as a food flavor additive.

Despite the claims of the Big Supplement, it is not a “natural” product (see the Appeal to Nature logical fallacy). Unless they’re harvesting billions of raspberries just to make a few pills.

The myth that these ketones would reduce weight was based on a single study in rats where 2% of the rat’s high-fat diet was replaced with these ketones. That would be an impossibly large amount of the ketones in the diet –an average human consumes about 1-2 kg of food per day. If 2% of that amount is converted to raspberry ketones, we’re talking about 20-40 grams of those ketones. 

That doesn’t sound bad, right. Except, 1 kg of raspberries contains about 2 mg of these ketones. You would need to eat around 2000-4000 kg of raspberries just to eat this amount. Or a 100 or so of those raspberry ketone supplements. 

On the other hand, other better-designed studies have shown no evidence of weight loss in rats even at levels that are equivalent to 200X the amount that a human would consume. And there is not one single clinical trial that has been published showing that raspberry ketones have any benefit in weight loss.

Let’s be honest, despite Dr. Oz’s pseudoscientific push, raspberry ketones are just one of the many weight loss scams.

weight loss scams
Green coffee beans that won’t do anything for your weight. Photo by Battlecreek Coffee Roasters on Unsplash.

Weight loss scams – green coffee beans

Next up on our review of weight loss scams are green coffee beans, which are just unroasted coffee beans. The belief that green coffee beans had an effect on weight loss resulted from a study that touted the “efficacy of green coffee extract in weight loss.”

This study caused the next big thing in weight loss. However, as with most one-off studies (that is never repeated by other researchers), it’s very easy to criticize. Let’s turn to the good people at Science-Based Medicine, who can spot a good medical scam with one eye and both hands tied behind their backs, who take apart the study:

  • The study only involves 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 concomitant 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.” This is like the real standard for real clinical trials.
  • The green coffee study was published in Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy, which is not a highly respected journal in this field. For example, even though the journal claims to be peer-reviewed, the time period from submission to the editorial decision was 12 days which means review was “cursory.”
  • None of the authors were clinicians or experts in the field. 
  • The authors claimed that the study was double-blinded, but because of the methodology of the study, 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 evidence as of yet.  And a systematic review of the research into green coffee beans and weight loss lead 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.”

A more recent systematic review, published in 2019 in Phytomedicine, a journal that promotes “herbal medicine.” Although it would appear to be a good review of studies, I was troubled by several issues:

  1. The authors are not located in a premier research institution. That doesn’t mean it is necessarily bad, but top medical research does not frequently come out of Iran, who doesn’t allow it’s researchers to travel to other countries to present their studies and accept criticism as necessary.
  2. The review includes all studies of green coffee, without applying standard review methodology – they don’t review bias, eliminating studies that just don’t make sense.
  3. They claim a “significant reduction” in BMI of -0.403 kg/m2. For a morbidly obese individual with a BMI > 35.0, that would be a 1.16% reduction, an almost clinically insignificant number. 
  4. Furthermore, with such a small reduction, confounders become a much more important component of the results.

This review does not provide robust (or even weak) evidence for an effect of green coffee in weight-loss.

And there are two clinical trials that have been registered to study the effect of green coffee beans on metabolic syndrome, which is linked to obesity and other lifestyle issues. The results of these studies have not been published in the two years since completion. Generally, it’s hard to publish negative results (which is annoying, since negative results are sometimes more valuable than positive ones), so we may never know anything about the studies.

Better method than raspberry ketones and green coffee to reduce weight. Photo by Gervyn Louis on Unsplash


Weight loss is rather simple. In general, the average calories burned has to exceed average calories consumed. Eat less. Burn more. Your choice. If you’re looking for the 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!


  1. Yes, this is an article that is not about vaccines. I actually used to only write about vaccines around 1/4 of the time, but with all the anti-vaccine garbage floating around the internet, it’s difficult to focus on other topics that interest me. I’ve been wanting to update this article for months, so here we go.

This article was first published on November 2013. Because of another surge in interest in these weight loss scams, this article needed a good update and refreshing. 


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