• “Fat Burners” or Money Wasters?

    By Edzard Ernst

    Originally published Tuesday 26 November 2013

    card-073-Edzard-ErnstPyruvate, a ketone and an alpha-keto acid, occurs naturally in the body when glucose is converted into energy. It is part of the Krebs cycle, the complex chain of reactions in which nutrients are metabolised to provide energy. High doses of pyruvate seem to stimulate the breakdown of fat in the body. It is therefore not surprising that pyruvate is used in all sorts of slimming aids; and if the advertising for ‘fat burners’ is to be believed, pyruvate is just the ticket for the desperate slimmer.

    One such product advertisement, for instance, claims that sodium pyruvate and potassium pyruvate, which can act as a stimulant for the metabolism, adding to the thermogenesis process. Pyruvates have been found in studies to reduced the storage of fat in the body and convert the food source into calories which are then burned off in the production of heat. In one study, rats were injected with three fat burners, including pyruvates, and the rats given the pyruvates burned the greatest amount of fat by increasing the rat’s resting metabolic rate. With the elevated resting metabolic rate, the body burned more fat in individuals, which makes pyruvate an excellent source for weight maintenance.

    So, maybe pyruvate works for rats – but does it really help those of us who would like to lose a few kilos? Some studies seem to say so, but others don’t. What do we conclude? There can only be one solution: we need a systematic review of the totality of the available trial evidence – and you probably guessed it: we have just published such an article.

    The objective of our systematic review was to examine the efficacy of pyruvate in reducing body weight. Extensive literature searches identifies 9 RCTs of which 6 were met our inclusion criteria. All had methodological weaknesses. The meta-analysis revealed a statistically significant difference of 0.72 kg in body weight with pyruvate compared to placebo. The magnitude of the effect is small, and its clinical relevance is therefore uncertain. Adverse events included gas, bloating, diarrhoea, and increase in low-density lipoprotein cholesterol.

    Our conclusion: The evidence from randomized clinical trials does not convincingly show that pyruvate is efficacious in reducing body weight. Limited evidence exists about the safety of pyruvate. Future trials involving the use of this supplement should be more rigorous and better reported.

    Pyruvate supplements are popular; people who want to lose weight are misled into believing that they are effective. Bodybuilders as well as other athletes tend to take them because pyruvate is claimed to reduce body fat and enhance the ability to use energy more efficiently. None of these assumptions is based on sound evidence. Regardless of the evidence, a whole industry is exploiting the gullible and doing very well on it.

    As these ‘fat burners’ are by no means cheap, I recommend a more efficient and more economical method for normalising body weight: eat a little less and move a bit more – I know it’s naff, but it works!

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    Edzard Ernst MD, PhD, FMedSci, FSB, FRCP, FRCPEd

    Emeritus Professor, Exeter University

    EErnstDr. Ernst qualified as a physician in Germany in 1978 where he also completed his MD and PhD theses. He received hands-on training in acupuncture, autogenic training, herbalism, homoeopathy, massage therapy and spinal manipulation.

    Later, he became Professor in Physical Medicine and Rehabilitation (PMR) at Hannover Medical School and Head of the PMR Department at the University of Vienna. In 1993, he moved to the UK and became Chair in Complementary Medicine at the University of Exeter. He is founder/Editor-in-Chief of two medical journals (Perfusion and Focus on Alternative and Complementary Therapies).

    He has published 48 books and more than 1000 articles in the peer-reviewed medical literature. His work has been awarded with 14 scientific prizes. In 1999, he took British nationality.

    His research focussed on the critical evaluation of all aspects of alternative medicine. Unlike most of his colleagues, he does not aim to promote a particular therapy. His goal is to provide objective evidence and reliable information. It is fair to say that this ambition did not endear him to many quasi-religious believers in alternative medicine.

    Healthy Skepticism is republishing selections from Dr. Ernst’s blog with permission. Please visit his website at http://edzardernst.com

    Category: Edzard ErnstFeaturedFitnessNutrition & SupplementsSkepticism

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