Raspberry ketone - the weight loss wonder?
When wanting to see instant results, many people turn to raspberry ketone supplements hoping for rapid weight loss. I evaluated the claims for miraculous and rapid weight loss using raspberry ketone supplements and was quite surprised with what I found.
What are raspberry ketone?
Raspberry ketone is a compound found naturally in red raspberries as well as a number of other fruits including kiwifruit responsible for the fruity aroma. It is found naturally in very small quantities in raspberries (meaning you'd have to eat bucket loads to get any effect) and is often synthetically created.
Claim to fame with weight loss?
According to some of the advertising used to promote raspberry ketone supplements, regular use (combined with a healthy diet and exercise of course) can do the following:
Burn fat
Help you lose weight
Boost your metabolism
Increase energy
Fight fatigue
But lack proof.
Most ketone supplements are pretty vague about where the evidence for their claims originated. If you ask Dr Oz, he'll tell you that raspberry ketone supplements are a 'number 1 miracle in a bottle to burn your fat'. But looking at his 'what the science says about raspberry ketone' page, you'll discover that his recommendation is actually based upon promising animal and test tube studies. Not quite the same thing!
What does the research say?
Contrary to what the ads would have you believe, there is actually only ONE study evaluating the effect of raspberry ketones in humans. I couldn't believe it! Surely something so popular and mainstream would have more evidence?!
Published this year in the Journal of the International Society of Sports Nutrition, this study randomised 70 obese but otherwise healthy subjects to either a combined supplement containing numerous ingredients including raspberry ketone, caffeine, capsaicin, garlic and ginger or a placebo. They took the supplement or placebo for 8 weeks while undertaking a calorie-restricted diet (reduced by 500kcal per day) and exercise training (3x 60 minute boot camp style sessions per week). Of the 70 enrolled, 25 participants were lost to follow up with 18 taking the placebo and 27 taking the supplement completing the study.
Participants taking the supplement lost an average 1.9kg total weight and 2.9kg body fat over the 8 weeks, while gaining an average 1.8kg lean body mass. These were significant differences compared to the placebo group.
However, because the supplement contained a mixture of ingredients it is difficult to prove that the raspberry ketone component specifically influenced the weight loss observed. Especially since we don't know how much raspberry ketone was in it to begin with!
Nutritional composition of the raspberry ketone supplement used in a human study. Lopez et al 2013
All other studies to date (of which there are few) have been either conducted in rats, mice or test tubes. No studies on safety, none on appropriate doses and none looking at how effective raspberry ketone supplements are if you don't cut back on your eating and exercise at the same time.
My advice?
Really? 2 kilo's in 2 months?! I may sound slightly sarcastic here, but with the only human research suggesting that taking raspberry ketone supplements can help you lose about 0.25kg a week ONLY if you cut back your eating by 500kcal (1200kJ) and do 3x 60 minute bootcamp sessions a week at the same time... I don't think they really live up to the hype and suggest you save your money.
Gemma
REFERENCES
Dietitians of Canada. Are raspberry ketone supplements safe and effective for weight loss among overweight or obese adults? In: Practice-based Evidence in Nutrition (PEN) http://www.pennutrition.com/ (Access by subscription only)
Ulbricht et al (2013) Raspberry Ketone An Evidence-Based Systematic Review by the Natural Standard Research Collaboration. Alternative and Complementary Therapies 19(2) 98-100
Lopez et al (2013) 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. Journal of the International Society of Sports Nutrition 10:22 http://www.jissn.com/content/10/1/22
Park KS. (2010) Raspberry ketone increases both lipolysis and fatty acid oxidation in 3T3-L1 adipocytes. Planta Med. 76:1654-1658.
Morimoto C, Satoh Y, Hara M, et al. (2005) Anti-obese action of raspberry ketone. Life Sci. 77:194-204
Gemma Sampson RD APD
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