Raspberry Ketones For Weight Loss

Last updated March 30th 2015

Raspberry ketones are a very popular, but little studied, ingredient found in a variety of weight loss supplements. They have been featured on the Dr. Oz show and claim to work by burning fat and boosting the metabolism.

The industry for weight loss supplements is growing rapidly, and with rates of obesity higher than ever before, people are searching for a quick and easy way to lose weight. So far, there is no ‘miracle cure’ to obesity that doesn’t involve eating healthily or doing any exercise. That being said, a number of products that have been released on to the weight loss market claim to do just that. It is extremely important that you do your research before taking a new diet supplement; these products do not have to be approved by the FDA, and so many are unlikely to have any impact on your health whatsoever, and may even cause your body harm.

What Are Raspberry Ketones?

Raspberry ketones are best known to be extracted from red raspberries, but they can also be found in other fruits such as cranberries, blackberries, and kiwis. Before they made an appearance on the weight loss market, raspberry ketones were used as food flavouring, and have even been used in the cosmetics industry. They are also believed by some to aid the regrowth of hair if applied directly to the scalp, though there is little scientific evidence for this.

The ketones used in the food industry have been approved by the FDA, however, those used in dietary supplements are not derived directly from raspberries; instead, they are synthetic substances allowing them to be produced at much higher concentrations than the natural form. From a kilogram of raspberries, it is usually possible to extract approximately 1-4 mg of raspberry ketones.

After being promoted on the popular television programme, the ‘Dr. Oz Show’, the ingredient has grown hugely in popularity, despite a lack of certain proof that they are effective as an aid to weight loss in humans. Scientific studies have been undertaken on the substance, but as will be discussed in further detail below, there is very little evidence for it having a significant impact on weight loss in human subjects

How Are Raspberry Ketones Claimed To Help Weight Loss?

Generally speaking, weight loss products that contain raspberry ketones claim that it works as a fat burner and a metabolism booster. The occasional product website will also mention that it works to suppress the appetite. The majority of fat burning products on the weight loss market purport to work by increasing the activity of the enzymes that naturally occur in the body that break down fat. This means that whilst the fat that you consume in your diet is still absorbed into your system, it is broken down before it becomes stored. You could therefore potentially lose weight whilst still consuming some fatty foods in the diet.

Products purporting to work as metabolism boosters tend to work in a similar way. These usually contain ingredients that speed up the breakdown of fat, and make the inside of the body more active – thus burning more energy than usual. Metabolism boosting product may also contain stimulants, such as caffeine, that potentially increase the amount of exercise that you undertake, and provide you with the feeling of having more energy. Appetite suppressants generally work by altering the amounts of certain neurotransmitters in the brain that are related to appetite. The most commonly targeted of these is serotonin.
Raspberry ketones are chemicals, and so exactly how these work at a finer scale within the body to achieve weight loss through the mechanisms described above is something that is not well understood. It seems that the claims are often based on the experiences of people who have taken the product, and so they may be related to psychological effects. Scientific studies on the matter are largely inconclusive, as will be discussed in more detail below. It is likely that raspberry ketones will not make a significant difference to your weight loss regime unless combined with a healthy diet and regular exercise.

What Does Dr Oz Say About Raspberry Ketones?

The Dr. Oz Show is one of the most popular television programmes that regularly discusses and analyses products available on the weight loss market in the United Stated of America. Raspberry ketones featured on the Dr. Oz Show in 2012. The ingredient was shown in a very positive light, implying that the chemicals in the product help to ‘shrivel up’ fat cells, and help your body ‘feel thinner’. Retailers jumped on this recommendation after Dr. Oz described it as a ‘miracle in a bottle’, and the product began flying off the shelves.

Controversy later arose when it became known that the woman who was promoting the ingredient with Dr. Oz on the show (Lisa Lynn) sells raspberry ketones. It is thus not entirely certain that the segment was filmed from an entirely unbiased, reliable perspective. Throughout the segment on the Dr. Oz show, no scientific studies were mentioned, and the exact mechanism by which the product supposedly works was not described in detail. The only aspect of science described was that it apparently increases the amount of the hormone ‘adiponectin’; it is this hormone that, according to Dr. Oz, makes your body think it’s thin. Precisely how this would help you to lose weight is not explained.

Is There Any Evidence To Support Claims Regarding Raspberry Ketones & Weight Loss?

One of the first published studies to highlight the potential of raspberry ketones as weight loss aids was undertaken on rodents, and the results were published in 2005 (study can be found here). This is the study that is often used as proof of the effectiveness of raspberry ketone supplements, but do bear in mind that it was performed on mice. The study was performed as raspberry ketones were identified as being similar in structure to capsaicin and synephrine – two compounds that are thought to have an impact on obesity and fat metabolism. The authors thus aimed to test whether or not raspberry ketones exerted similar actions. In the study, mice were given a high fat diet, and included 0.5, 1, or 2% raspberry ketone for a period of 10 weeks. The results indicated that raspberry ketones prevented weight gain in mice caused by high fat diets. Fatty liver was also reduced. It was concluded that the substance probably worked by increasing lipid metabolism.

Since the publication of the aforementioned study, several other experiments have been performed. In 2010 a study by Park was published, using test-tube based methods, rather than experimenting on animal subjects (find it here). This study attempted to clarify whether or not raspberry ketones impacted weight loss, and if so, exactly what mechanism is used to achieve this. The findings suggested that raspberry ketone increased lipolysis in individual cells; it was also stated that fatty acid oxidation was increased and lipid accumulation suppressed. The authors concluded that raspberry ketones might hold promise as weight loss agents.

Another study of the effects of raspberry ketones in rats was published in the Journal of Medicinal Food in 2012 (available to view here). In this study, rats were split in to five different groups, these groups included: 1: rats were given no raspberry ketones and fed a normal diet, 2: rats were fed a high fat diet and 0.5% raspberry ketone, 3: rats were fed a high fat diet and 1% raspberry ketone, 4: rats were fed a high fat diet and 2% raspberry ketone, and 5: a control group fed just a high fat diet for four weeks. Each group contained eight rats. The results indicated that raspberry ketones were effective at protecting the liver and inducing fat reduction.

Some of these results may seem positive, however it must not be forgotten that no scientific studies whatsoever have been undertaken to test the impact of raspberry ketones on weight loss and fat breakdown in human subjects. This is important because results obtained from rodent studies are by no means directly transferable to humans. Until more studies have been undertaken on human subjects, there is no way of knowing for certain whether or not raspberry ketones have any positive (or indeed negative) impacts on humans. Note also that each of these studies imply that the substance may help in the breakdown of fat, and increasing the speed of metabolism, but there does not appear to be any evidence for an impact on the appetite thus far.

How Do Raspberry Ketones Compare To Other Ingredients?

It is very difficult to choose a weight loss supplement that is likely to work best for you when there are so many similar products available to buy. Here raspberry ketones will be compared with several other ingredients that are commonly found in diet pills. Raspberry ketones have been the subject of some scientific studies, which is more than can be said for a lot of weight loss ingredients on the market. It is important to mention that one diet pill will not work best for everybody – people’s bodies and lifestyles vary, and as such, there may be areas of weight loss that work better for some people than for others.

Raspberry Ketones And Garcinia Cambogia

Whilst raspberry ketones supposedly work by increasing the speed at which fat is burnt once absorbed by the body, Garcinia cambogia is believed to work by preventing fat from being absorbed in the first place. This is potentially achieved by the substance binding to the fat molecules, making them too large to be absorbed through the lining of the small intestine. Garcinia cambogia is also often advertised as having properties related to appetite suppression, although it is not clear exactly what mechanism is supposedly used to achieve this.

In terms of clinical studies, both ingredients are at a similar stage of study. The majority of studies undertaken on Garcinia cambogia, like those on raspberry ketones, have been undertaken on rats and mice. A reduction in fat accumulation in animal subjects consuming Garcinia cambogia has been seen (e.g. this study and this trial), but the same results have not been found in studies on humans.

One study that was performed on humans can be found here. The results of this study found that Garcinia cambogia had no significant effect on the fat or glucose levels of human subjects, although it did appear to have an impact on cholesterol levels, where levels were significantly lower in the test group (consuming Garcinia cambogia) than the control group.

Raspberry Ketones And Acai Berry Extract

Very few scientific studies have been undertaken on the effectiveness of Acai berry as a weight loss agent. A literature review reveals only one published study on Acai berry, and although it is performed on human subjects, only 10 volunteers were used – this is a very small subject quantity for a clinical trial, and thus any results should be taken with a pinch of salt. It also did not contain a control group. Control groups are very important elements of clinical studies to verify the results. The pilot study was published in the Nutrition Journal, and can be found here. The experiment was designed to test the benefits of Acai berry on the risk factors for metabolic disorders in overweight individuals. The results seemed to suggest the substance might cause a decrease in cholesterol, fasting glucose and insulin levels. No results were given directly relating to the burning of fat.

Websites suggest that Acai berry may help to burn fat, boost metabolism, and reduce appetite. Overall, the single study that has been performed on the ingredient is not very reliable, and the results not overly significant. More studies certainly need to be undertaken on Acai berry, and at present, raspberry ketones seem to be better studied.

Raspberry Ketones And Green Coffee Bean Extract

Green coffee beans supposedly aid weight loss in similar ways to raspberry ketones – by helping to burn fat quicker, boost metabolism, and suppress the appetite. These claims are however not well backed up by scientific studies. Green coffee bean extract has been the subject of several clinical trials that attempted to determine its effectiveness. A meta-analysis of studies performed on the effect of green coffee extract on humans can be found here. This analysis included five studies and concluded from these, that the effect is only moderate, and there significantly contrasting results have been found between studies. The results may be promising, but the quality of the trials is poor, and so more studies need to be undertaken on the ingredient.

Some individual studies can be pointed out, for example this study that showed positive results in rat subjects. This study on human subjects is another example that showed positive results for weight loss, but again was only performed on a very low number of subjects (16 including the control group). Although the results appear positive, more detailed, larger studies definitely need to be performed on the potential impact of both raspberry ketones and green coffee beans on weight loss in human subjects.

Are There Any Other Benefits To Raspberry Ketones?

Raspberry ketones have been useful as flavourings of foods for many years, and have even been shown to be beneficial in the cosmetics industry, with a possible benefit in helping hair regrowth, and helping to rejuvenate skin. Unfortunately, the proven benefits of raspberry ketones do not appear to stretch to weight loss. Raspberry ketone supplements can no longer legally be sold in the United Kingdom, and so having to buy them online adds another level of complication, and finding a good, reliable online retailer can be challenging. That being said, at least raspberry ketones are very well known, and have been the subject of a significant amount of media attention – in turn it is possible to find the ingredient in products sold by some leading brands in the weight loss market. Their popularity also means that it is relatively easy to find independent customer reviews of the ingredient.

The scientific studies that have been performed on raspberry ketones have not produced negative results, and may imply that raspberry ketones could have a moderate impact on overweight patients trying to lose weight. The main concern is that to date, the studies have only been performed on small mammals, and so there is no direct evidence that the ingredient will produce the same results in humans.

Raspberry ketones found in supplements are not even derived from natural sources, as is the case for a number of other weight loss supplement ingredients, and indeed as may be expected based on their name. One positive note is that there are few reported side effects of raspberry ketones in the short term, and they do not appear to alter your digestive system too much (as is often the case for weight loss supplements). There are still possible side effects relating to the ingredient; these are discussed in more detail below.


What Side Effects Are Associated With Raspberry Ketones?

Virtually all weight loss products have some potential side effects, and raspberry ketones are no exception. Overall, the known short-term side effects of the ingredient tend to be mild. The lack of long-term scientific studies on the ingredient does however mean that it is not known for certain whether or not there may be any long-term side effects, or what these could be. Raspberry ketone is deemed to be generally safe by the FDA as a food additive, but has not been analysed in the concentrations that it is found in in supplement form.

Side effects that have been reported in the past include jitteriness, anxiety, increased heart rate, and increased blood pressure. Whether or not these are directly related to the ingredient is unclear, but if you suffer from any of these side effects it is recommended that you stop taking the product and consult a doctor. This may also not be a comprehensive list of possible side effects, as only a limited amount of studies have been performed on the substance. If you suffer from any pre-existing health condition (particularly relating to the cardiovascular or nervous systems), are pregnant, breastfeeding, or are under the age of 18, then it would be recommended that you consult a physician before consuming products containing raspberry ketone.


Are Raspberry Ketones Legal?

Despite still being available to buy in some stores around the United Kingdom, in March 2014, the Food Safety Agency (FSA) confirmed that not all raspberry ketones should be sold as supplements in the United Kingdom because regulatory authorities have not approved them. The FSA refer to raspberry ketones as a ‘novel food’, and that products containing them should go through approval via the Advisory Committee on Novel Foods and Processes (ACNFP) in the UK. A ‘novel food’ is one that was not consumed to a significant degree before mid-May 1997. On the FSA website it is stated that certain raspberry ketone extracts are included as ‘novel’, and thus are unauthorised.

For this reason, it seems that raspberry ketone supplements alone, or the ingredient in other weight loss products, are not legally sold in the United Kingdom, or indeed in the whole of the European Union. It is possible that the product can still be found in stores such as Holland and Barrett because the regulations are not yet being fully enforced. The only legal form of raspberry ketones (excluding its use as a flavouring) is where the extracts were prepared using water or 20% ethanol. It is very difficult to find this information on product websites.

 Where Can You Buy Raspberry Ketones?

Raspberry ketones are available to buy from a wide range of retailers online, and it is important that you choose a product created by a reliable manufacturer, and sold by a reliable retailer. Despite recent regulations against their sale, it is still possible to find raspberry ketone supplements, as well as combination weight loss products containing the ingredient, on the shelves of retailers in the UK, for example Holland and Barrett. They are also available to buy from online retailers such as Amazon and Ebay, but be aware that these may not be as safe – make sure that you do your research on the company selling the product through these websites before purchasing.

 Beware Of Raspberry Ketone Scams

‘Free trial’ scams are all too common amongst the weight loss supplement market. These types of scam usually involve enticing customers in by offering a free trial of the product, i.e. a supply to last one month. Customers enter their contact and payment details before applying for this ‘free trial’, and if they do not read the terms and conditions, often get caught up in the scam. Although it is advertised as a free trial, the small print often states that if you do not cancel your subscription within a certain amount of time you are liable to pay for the ‘free trial’ bottle and then a bottle every month from then on. This money will come straight out of your account without any further warning.

Some ‘free trial’ scams are known for raspberry ketones, such as ‘Super Ketone Plus’ and  ‘Raspberry Ketone Blast’, but they are being formed all the time, and so there are likely to be new retailers working on a ‘free trial’ scam basis that have not already been identified. These scams usually operate through a website. For this reason, be sure to research the company you are about to buy from thoroughly, and always be wary of any websites offering free trials.

What To Look For In A Raspberry Ketone Retailer

Perhaps the safest way to buy raspberry ketone is by browsing shops on the high street that sell health products. The best example of these at present is Holland and Barrett. Purchasing off the internet can be more risky, even though you may be able to find a product for a cheaper price. If you do choose to purchase from the internet, be sure that you research both the retailer and the manufacturer thoroughly before entering your details.

There are a number of features that you should look out for when buying from a website you haven’t purchased from before. Look for things like a money back guarantee, good details about the product and how it is supposed to work, mention of who manufactures the product (and then research the manufacturers too), and finally check that there are full contact details for the company, not just an online form to fill in.

Searching for independent customer reviews (don’t always trust the reviews provided on the website itself) can also help to give you a good idea of how reliable the website is. Customer reviews can give you a better idea of how long the company have been established, whether the products reached the customers as expected, and how efficient the returns policy was.


In conclusion, raspberry ketones have been the subject of a large amount of ‘hype’ thanks to the media, and in particular to the Dr. Oz Show. Unfortunately, the popularity of the product is not well backed up by scientific studies, which are to date, entirely restricted to experimentation on rodents. For this reason, it is not possible to state that the ingredient is the ‘miracle’ cure to obesity as implied by Dr. Oz. The ingredient may offer the potential to help overweight patients lose a small amount of weight alongside a healthy diet and regular exercise, but the benefits (or lack thereof) cannot be stated with certainty until more scientific studies have been performed.