Raspberries are one of my favorite fruits or berries. They are a staple in my smoothies, so the idea of a component of them being helpful for weight loss has my attention. This concept is especially true since a component of them would be a natural product, and one would think that this would make it less harmful and healthier. Then again, arsenic is natural but not healthy or suitable for you.   The raspberry ketones component has a lot of recent attention again as a possible weight loss aid, but is it hype or a hoax?  

I will focus on explaining what a raspberry ketone is and whether it works for weight loss based on research? With all the positive press aimed toward this supplement or another, it is easy to think that raspberry ketones are just what you need to lose weight. Most people will not have looked into research before committing to a supplement for weight loss. They will go to the local vitamin store and ask the expert behind the counter, who is hardly a non-biased source of information. They are vested in you buying the product and thus keeping a job.  

What is a raspberry ketone? A raspberry contains over 200 distinct molecules contributing to its unique flavor. One compound that contributes to the flavor is the raspberry ketone or 4-(4-hydroxyphenyl) butan-2-one, p-hydroxybenzyl acetone. You will notice that the structure is very similar to capsaicin, synephrine, and epinephrine(see the image to the right)(examin.com). Raspberry ketone is the natural phenolic compound in red raspberries, creating part of its flavor and odor. It is not a new compound. Manufacturers have used them for years to attract us to their products by adding that familiar smell.  

Raspberry ketone is not a compound unique to just raspberries.   It is also found in apples, blackberries, black raspberries, cranberries, black raspberries, grapes, kiwis, rhubarb, and peaches. Only trace or small amounts of raspberry ketone are found in the fruit, so most berry-flavored foods typically use raspberry ketone produced in a lab to make the flavor. Food manufacturers have been using it for years to create raspberry flavor and odor because it is the primary cause of the aromatic smell in raspberries. We all know that smell is bound to flavor, and if your sense of smell is lost, you will also lose a good portion of your ability to taste.  

What is the mechanism behind raspberry ketones? A raspberry ketone is, as is evident from its name, a compound that is naturally found in raspberries. Despite its similar structure to synephrine, raspberry ketone is said to be non-stimulatory which means that it does not cause an increase in heart rate or blood pressure. That being said, there is limited research to back up the claim. Manufacturers claim that raspberry ketone is helpful for weight loss because it increases adiponectin​[1]​, but most of the research has been done in mice. There is limited to no support for human models.   Adiponectin is one of the obesity hormones that is said to reduce hunger, so if it translates to human models, it should work for weight loss.  

Could I eat raspberries? I tend to recommend whole foods instead of supplements, but you would have to eat a lot of raspberries. The studies in rats used rather high doses with up to 1-3% of the diet by weight coming from raspberry ketones. That would correlate to 1,100-5,000mg for a 200lb person (examine.com).  That is one heck of a supplement since each pill available online is 100-400 mp of raspberry ketones. According to healthline.com, 2.2 kilograms of raspberries contain approximately 1-4 mg of raspberry ketones. This means you would have to consume between 25-100 pounds or 55-220 kilograms of raspberries to get the equivalent of the supplement pill. If you are shooting for 5000 mg to be the equivalent of some mice studies, you must consume as much as 250 pounds or 500 kilograms. One thing is certain if you eat that many raspberries, you will be regular.  

Does raspberry ketone work for weight loss? This belief is hype bordering on a hoax. There are insufficient human trials, but mice models indicate it should work. Several studies have shown that raspberry ketone reduces fat deposition and increases lipid metabolism through norepinephrine-induced lipolysis in white adipocytes​[2]​,​[3]​. Although raspberry ketone is a molecule marketed as a fat-burning compound, and it would appear that it might be effective in mice models, I could only find one human trial that seemed to support the use of this supplement. The study,“Eight weeks of supplementation with a multi-ingredient weight loss product enhances body composition, reduces hip and waist girth, and increases energy levels in overweight men and women,” was published in the International Journal for Forts Nutrition in 2013​[4]​. They found a supplement called METABO was safe and effective when added to an eight-week diet and exercise weight loss program. It resulted in improvements in body composition, waist, and hip circumference compared to a placebo. The problem is that the supplement is not a pure supplement but a proprietary mixture of raspberry ketone, caffeine, capsaicin, garlic, ginger, and citrus Aurantium.  

The bottom line:  Reliable research on using raspberry ketone for human weight loss is currently lacking. The equivalent dose in humans is too high and likely toxic. More research is needed to back up the outlandish claims in infomercials, the internet, and TV. I cannot recommend using raspberry ketone supplements for weight loss, but that does not mean that you can add a handful to your smoothies and enjoy the flavor.