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Evidence on Weight-Loss Supplements Found Too Light

Reader of these pages are probably well aware of the countless supplements, potions, pills, and other products being enthusiastically advertised (and sold) for weight loss.

Although this is a billion dollar market, most users of these products (after spending a fortune) will have realised that virtually none of them hold any of the advertised promises (viz. boosts your metabolism, burns fat, reduces appetite, abolishes hunger, shaves inches off your waistline, etc.).

Apparently, this is not just YOU for whom these products do not work – it turns out that the published scientific evidence (by no means available for all such products) is rather light (pun intended!).

Thus, a recent review of reviews on the evidence in support of such weight-loss supplements, published by Igho Onakpoya and colleagues from the University of Exeter, UK, in a recent issue of OBESITY, concludes that:

“…the existing systematic reviews of clinical trials testing the efficacy of food supplements in reducing body weight fail to provide good evidence that any of these preparations generate clinically relevant weight loss without undue risks.”

For their paper, the researchers conducted an extensive search of all relevant databases to identify review articles summarizing the data on individual weight-loss supplements.

Published reviews that met the eligibility and quality criteria were available only for the following supplements with rather modest (not to say non-existent) findings:

Guar gum: 20 randomized controlled trials (RCTs) including 366 participants: not efficacious for reducing body weight.

Chromium picolinate: 17 RCTs with 961 participants: a “relatively small” effect in reducing weight.

Ephedra: 17 RCTs with 1,451 participants: a significant short-term effect on body weight. Serious risks of Ephedra/ephedrine intake were also identified.

Citrus aurantium (bitter orange): 1 clinical trial with 23 participants: no significant effect on body weight.

Conjugated linoleic acid: 21 clinical trials with 852 participants: no significant effect on body weight.

Calcium: 13 RCTs with a total of 1,127 participants: no significant effect on body weight.

Glucomannan: 14 RCTs with 531 participants: significant (albeit small) reduction in body weight.

Chitosan: 15 RCTs with 1,219 participants: some evidence of short-term weight loss in obese and overweight individuals.

Camellia sinensis (green tea): 15 trials with 1,226 participants: efficacious for short-term weight reduction and weight maintenance.

Overall the authors come to the rather sobering conclusions that:

“Generally speaking, the results and conclusions of the systematic reviews are disappointing. In particular, they are limited by the often small sample sizes and low quality of the primary studies, and by the fact that some of them fail to control for lifestyle variables with important influence on body weight.”

The authors also don’t appear happy with the quality of the reviews:

“…several of the systematic reviews are flawed, for instance, through insufficient search strategies or a failure to account for the methodological quality of the primary studies. Systematic reviews that reported a “statistically significant effect” are limited by small effect sizes (e.g., chromium picolinate), and/or a high risk of adverse events (e.g., Ephedra). Clinically significant weight loss of at least 5% of body weight was not achieved. The short duration of most of the primary studies is a further drawback. Therefore, none of the nine food supplements discussed above are supported by sound evidence from systematic reviews for generating clinically relevant effects on body weight without undue risks.”

Not that any of this is likely to cut into the profits of the “all-natural” weight-loss supplement market – after all it is hard to get people to stop spending their hard-earned dollars on hope (and of course, it is their money to spend).

Nevertheless, this is the kind of information that is likely to be available to Canadians through the COACH initiative.

I know I could be opening a can of worms by asking my readers to share their insights and experience with weight-loss supplements but I am guessing that other readers will probably find this of interest.

Edmonton, Alberta

Onakpoya IJ, Wider B, Pittler MH, & Ernst E (2011). Food supplements for body weight reduction: a systematic review of systematic reviews. Obesity (Silver Spring, Md.), 19 (2), 239-44 PMID: 20814412


  1. I haven’t tried a wieght loss supplement program since I was a teenager in the 1970s. At that time the fad was cider vinegar, lecithin, vitamin B6 and kelp supplements taken together. Which of course didn’t work. I don’t believe any claims about products so don’t buy them. I don’t buy lottery tickets either.

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  2. Early in this weight loss venture, I suffered from severe cravings for specific foods, and still occasionally suffer from those same cravings. The logical solution, to eliminate those particular cravings, is to find the correct supplement and take that supplement, assuming the craving is caused by a deficiency of a particular mineral, vitamin or protein. I tried a lot of different things. Some worked, some did not.

    It became apparent that there was no room in my diet for calorie dense – low bio-available nutrition foods, such as sugar, grains, manufactured oils, and other manufactured eatable products. I was better off to take the chemicals and leaving out the calories. I am down more than 55 Kgs.

    The next issue was the recommended (required) dose of each vitamin and mineral or protein. There is much debate over some, and a total lack of information, reliable or otherwise, on others. There are also mutually exclusive recommendations from government agencies. What is a person to think? One conclusion is that none of them are right.

    It is suggested that a shortage of a vitamin or mineral will cause cravings, which may lead to overeating, which likely will lead to weight gain. I also could find no evidence that sufficient vitamin and mineral will lead to weight loss; however, it seems logical that it will be easier to follow a weight loss plan without vitamin and mineral deficiencies caused cravings, if they actually do.

    The next issue can be found on the utility-dose curve. If we are below our “personal daily requirement” the supplement will have value. If we are above, it will not. At some point there may be a risk associated with ingestion of some. There are also sub-clinical deficiencies, where the clinical deficiencies symptoms are mild and assumed to be normal, but go away with minor amounts of vitamins. I suffered most of my life from red skin patches, saw numerous doctors and dermatologists, tests, drugs, all to no avail, and they went away within days after I started Vit D at 5000IU/day. Perhaps it was just coincidence, or not.

    Our “personal daily requirement” is dependent on our personal ability to absorb and the conditions of ingestion. Fat soluble vitamins need to be taken with fat. Mal-absorption of vitamins can also make my personal requirement of specific vitamins considerably higher. I now take 1.5 gms of Vit C twice per day, plus a list of other vitamins and minerals and that seems to reduce the cravings considerably.

    My credentials are not in nutrition, I just read and test stuff on myself.

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  3. I guess people are always looking for the “easy fix”. As an RD who does NOT practice in the area of weight loss management, I am sometimes quizzed by co-workers about their latest “find” – the magic bullet, so to speak and what do I think of it? My message to them is obviously not sexy enough or doesn’t promise instant results, because I frequently see them going back to the pill or powder or magic drink. As a health care professional, it’s frustrating to be ignored!! And I also hate to see how much money is being spent on this useless stuff!!

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  4. I took ephedrine with ASA and caffiene years ago when I was desparate to lose weight. It resulted in heart palpitations. I also took hydroxycut for a time, but my feeling is that it results in a rebound effect when you come off of it. I am learning that my biggest problem with weight fluctuations is stress and sleep. These issues cannot be fixed with a pill.

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  5. My brother-in-law took Metabolife (Ephedra). The family is convinced that it was responsible for his subsequent need for heart surgery.

    I don’t see HCG in the above list. I am betting it will be as disappointing as the rest, but hopefully not as dangerous as ephedra. Oh, and Sensa: fairy dust you sprinkle on your food. Yeesh.

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  6. Thanks for your share with us friend! i am a fat girl,i am crazy for my fat body,i can’t wear beautiful clothes like other girls,i really want to loss weight,so i make exercise everyday and drink much water,only eat vegetables

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  7. I’ve got my fair share of experience with weight loss supps, both from my own playing with my body, and from helping clients over the years as a personal trainer.

    I can say that the only one I find personally useful is caffeine, mostly coming from coffee, but not to accelerate fat loss in any way, but as an appetite suppressant. I find that I can fast pretty easily from morning to mid afternoon with only one or two coffees inside me, but that without the coffee I get ravenously hungry by noon. Nothing else I’ve tried really makes much difference to me, but clients have found various things useful, some of which I wrote about in this blog post about some of the crucial factors that lead to successful fat loss:

    One thing, above all others, that makes a difference in fat loss is forgetting about ‘the magic bullet’ and concentrating on creating a good, consistent diet and exercise schedule that makes you feel good and filled with energy.

    My 2c,

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