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Do fat burners really work? 21 studies compared
April 16, 2024
Do fat burners really work?
Fat burner supplements are everywhere. On supermarket shelves, in pharmacies, in supplement shops. Sold as the miracle solution for losing weight fast. But I don't fall for it any more.
I'm tired of their catchy promises, of the colourful labels boasting almost magical properties. "Speed up your metabolism and melt away excess fat!" they shout. But is that really how it works? I've learnt to be sceptical.
What exactly is a fat burner supplement? A compound or blend of natural or synthetic ingredients meant to increase fat burning in the body. They often contain caffeine and plant extracts such as green tea, garcinia cambogia and chilli pepper. All combined with vitamins and amino acids to give a more "wholesome" feel.
Not to be confused with draining supplements, which can instead have noticeable diuretic effects helping the elimination of excess fluids.
What is the thermogenic principle supposed to be?
The underlying theory is simple: these products are said to stimulate the metabolism and thermogenesis, in other words the production of heat by the body. So you would burn more calories and more fat to produce energy. An appealing idea, one that plays on our innate hope of losing weight without too much effort.
Some of these plants are advertised as being able to interfere even with the absorption or storage of lipids in the body, thereby preventing them from building up as fat. Another promise that sounds tempting to anyone who wants to slim down their belly or thighs.
These "slimming elixirs" are often recommended alongside a low-calorie diet. The idea is that they speed up fat loss while at the same time preserving precious muscle mass. That is not always an easy goal to reach when you are following a restrictive eating plan.
But beyond the talk and the eye-catching advertising, the question is: do these supplements really work? I started to have my doubts after being dazzled too many times by the flattery of "miracle" pills and powders
Scientific evidence on the ineffectiveness of fat burner supplements
Science opened my eyes.
A 2021 piece of research, the systematic review and meta-analysis published in BMC Complementary Medicine and Therapies by James E. Clark and Sarah Welch of the University of New Mexico, analysed the results of no fewer than 21 scientific studies on the real effectiveness of these "fat burning" supplements. All of them were carried out on people who were overweight or obese, for at least 8 weeks.
The aim? To assess whether these products genuinely supported the loss of total body weight and fat mass, as well as improving health markers such as cholesterol and basal metabolic rate.
The results were compared with people who were simply following a diet or taking exercise, without taking any supplement. And do you know what came out of it? Absolutely nothing!
Sure, thermogenic and fat-burning supplements seemed to give some marginal benefit on body mass and fat stores. But the 95% confidence interval of the effect size (the size of the statistical effect) crossed zero for every variable considered.
Translation? No real, appreciable and statistically significant advantage, as reported in the study.
The final blow came from the direct comparison with people who had lost weight purely through a healthier lifestyle. A low-calorie diet and regular exercise, with no concoctions of any kind. Well, these approaches proved to be clearly more effective at promoting weight loss and fat loss, as well as reducing cardiometabolic risk factors.
Compared with those miracle supplements, following a balanced diet and moving more produced robust, proven results. A cold shower for anyone who, like me, had hoped for an easy shortcut back into shape after the exhaustion of motherhood.
The authors of the research were clear: the available data show extremely limited benefits from taking these thermogenic and fat-burning dietary supplements. And yet, how heavily they are advertised as the cure-all for shedding those extra kilos!
Companies stake everything on sensationalist, misleading claims, playing up the almost miraculous qualities of these products. But the reality is very different. Science dismisses these "magic" pills as entirely ineffective, as the study concluded.
The phantom miracle fat-burning ingredients
So what are the ingredients in these supplements that are passed off as so effective? Many of them contain a blend of plants, herbs and substances of natural origin, credited with astonishing fat-burning and metabolism-boosting properties.
One of the most common plants in these slimming products is without doubt green tea. This drink, rich in polyphenols such as catechins, has long been celebrated for its potential antioxidant and anti-inflammatory effects and its ability to support energy expenditure and thermogenesis.
But the scientific studies that have assessed its effectiveness in promoting fat loss have produced conflicting results. Some research suggests a slight advantage, while other studies found no significant impact at all. In short, nothing conclusive.
Another very popular ingredient is garcinia cambogia, a tropical plant whose active compound, hydroxycitric acid (HCA), is supposedly an inhibitor of fat accumulation and of fatty acid production. Unfortunately, the evidence supporting this hypothesis is genuinely scarce. Most well-conducted studies have found no appreciable effect on body composition linked to taking this exotic plant.
But there is one ingredient that is never missing from these supplements: caffeine. Often extracted from maté or guarana, as well as being present in green tea. This stimulant is known to increase energy levels, mental focus and thermogenesis, that is, the production of heat by the body. Some studies suggest that caffeine can indeed support a slight increase in calorie expenditure. However, the effects on long-term weight loss are generally modest and not clinically relevant unless combined with a low-calorie diet and consistent exercise.
Which other plants are supposed to burn fat?
Other plants that are never missing from these supplements are chilli pepper, whose capsaicin is said to stimulate the metabolism slightly, glucomannan, which might promote a longer-lasting feeling of fullness, cinnamon, said to act on the regulation of blood sugar levels, and rhubarb, assumed to be a mild diuretic able to support the elimination of excess fluids. However, here too there is a lack of solid, consistent evidence of any appreciable effectiveness of these ingredients on body fat loss.
It is important to stress that even where some of these natural active compounds did exert modest fat-burning or metabolism-boosting effects, these still cannot be compared with those brought about by an active lifestyle and a healthy, balanced, low-calorie diet. Following a balanced diet rich in fibre and protein with a controlled calorie intake, combined with regular aerobic activity and resistance training, produces clearly superior benefits.
Should I buy a fat burner or not?
In summary, despite the tempting promises about the effectiveness of fat burner supplements, based above all on the presence of natural ingredients and plants with supposed slimming properties, the scientific evidence supporting these effects is anything but convincing.
While mild thermogenic activity is plausible, these products certainly cannot replace a holistic approach that includes healthy, low-calorie eating and regular exercise. The end effect on fat loss therefore remains extremely limited.
So, dear friends, the next time you come across those colourful packs at the supermarket or in the gym promising to make you slim in the blink of an eye, don't fall for it! Remember that the secret to being in great shape is not in slimming pills, but in a healthy, active life every day — and if you would like some help draining excess fluids, I recommend this Moringa-based draining treatment.
Not sure what Moringa is? Find out more here: what is moringa