Raspberry Ketones: What’s the Evidence?

Last year, I was doing some freelance work for a website that reviewed and examined diet products that were on the general market. It was my job to investigate the products, both of which were only available from the U.S, with one claiming to ‘melt’ the fat away whilst enlarging breasts and hips (if something seems too good to be true, odds are it is!). I had to go through the ingredients list and explain what they could potentially do and most importantly, I had to search for clinical trial data that could prove its effectiveness.

It’s fair to say that I wouldn’t recommended either of these products. They were, for the most part, caffeine tablets, with one positive user review mentioning that they got the shakes for about twenty minutes after taking the pills, but afterwards felt fine…

What I did notice though, was the heavy advertising of the wonder ingredient known as raspberry ketones.



What are raspberry ketones?

Raspberry ketone, put simply, is a naturally occurring chemical in raspberries (as well as cranberries and blackberries), which gives them their characteristic scent.


It can be added to other food products in order to give them a fruity scent and is also used in perfumes and cosmetics for the same reason. The organic compounds can be exceptionally expensive, so sometimes it’s easier and cheaper to produce a synthetic copy of the phenol.

They’re now marketed as being an ideal pill for weight loss, with the promise being a sped up metabolism and processing of fat. They’ve even been featured on the popular U.S television show The Dr. Oz show.

The evidence

Despite there being glowing recommendations in advertisements and user reviews, I’m afraid to say that there haven’t been any human clinical trials that show positive effects. In fact, there haven’t been any human clinical trials at all. So why are raspberry ketones being hailed as a weight loss product?

Well, there is one published, peer reviewed paper that shows the results of studies on raspberry ketones.

This study, published in 2005, was carried out in rodents. In the first study, the rats were given a high fat diet, with some receiving different doses of raspberry ketones for ten weeks. In the second, rates were fed a high fat diet for six weeks, before being separated into two groups. The first group continued with the diet for a further five weeks, whilst the others were given the same diet with added raspberry ketones.

At the end of each study, the livers of the rodents were examined, to see if the raspberry ketones had had any effect on the fat content and overall final weight. The results showed that in both studies, the raspberry ketones prevented as great a weight gain that was seen in the ketoneless counterparts. The team concluded that this is because raspberry ketones alter and improve the metabolism of fats.

What this means

Despite there only being this one study, producers and distributers of raspberry ketones have been using it as evidence for its effectiveness in humans. But what must be remembered is that any weight loss product that can truly claim results must be tested in humans, in a study that has gone through the peer review process.

But, alas, products such as these have saturated a market that is obsessed with getting you ‘thin’ (I’ve covered this topic before). Raspberry ketones are available here in the UK, at popular stores such as Holland and Barrett. I’ve also received offers from voucher websites, advertising deals on raspberry ketone pills and they can of course be bought online. This is all in spite of fact that the Food Standards Agency have deemed that raspberry ketones are a ‘novel’ food and therefore cannot legally be sold in the UK as a weight loss supplement.

So, if anyone ever recommends raspberry ketones or another supplement, because they’ve ‘heard’ about their benefits, I would recommend that you do some research. There are plenty of websites that can provide all the information that you need.


Have you used raspberry ketones or other supplements for weight loss? Comment below and add to the discussion!


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