Weight loss supplements are extremely popular for those seeking the promise of quick body fat loss, without having to clean up the eating habits or engage in more physical activity. In 2013, raspberry ketones featured on the Dr. Oz Show as the products were thought to assist the body to burn fat by “helping the body think it’s thin.” Dr. Oz dubbed raspberry ketone supplements as the “No. 1 miracle in a bottle to burn your fat” and ever since then, various brands have been flying off the shelves. However, I question and unearth the proof to substantiate such product claims.
What is it?
Raspberry ketones are compounds found naturally in red raspberries as well as a number of other fruits including kiwi fruit, which is 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. Historically, raspberry ketones have been used as a flavouring agent in food and as a fragrance in cosmetic products. The dosages in weight loss supplements far exceed that which would be used as a flavouring in food and so the safety of supplement use cannot be inferred from it’s use as a flavouring agent.
The True Science?
Retailers of raspberry ketone as a weight-loss aid base their claims on the
compound’s ability to increase circulating levels of adipo-nectin, a hormone
secreted from adipose (fatty) tissue
that plays a key role in carbohydrate and fat oxidation. In humans, low circulating levels of adipo-nectin
are linked with an excessively high BMI, a high percentage of body fat,
elevated fasting insulin concentrations and raised triglycerides. Therefore, high levels of
adipo-nectin have been indirectly associated with a decreased risk of obesity,
insulin resistance, metabolic syndrome and cardiovascular disease.
Some of the earliest research investigated the compound’s ability to prevented weight gain, improved liver fats and stimulated fat burning in fat storage cells of male mice fed a high fat diet. The truth of the situation is that what happens in a test tube or a mouse isn’t necessarily indicative of what happens in humans!
Contrary to what the advertisements would have you believe, there is actually only onestudy evaluating the effect of raspberry ketones in humans. In 2013, the Journal of the International Society of Sports Nutrition, randomised 70 obese but otherwise healthy people to either a combined supplement containing numerous ingredients including raspberry ketone, caffeine, capsaicin, garlic and ginger or a placebo. The participants took the supplement or placebo for 8 weeks while undertaking a calorie-restricted diet (reduced by 500kcal per day) and exercise (3x 60 minute sessions per week). 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 muscle. These results were clinically significant 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. The raspberry ketone content with the supplement wasn’t known to begin with, plus there was a calorie reduction and increase in physical activity levels to consider too.
The challenge is that many people want the next best thing and the quick fix answer to weight loss. I always query what happens when an individual stops taking such products? Weight regain and yo yo dieting are inevitable which often reduces self-confidence to lose weight in a safe manner i.e. healthy food consumed in appropriate portions and move more.
