No Strong Evidence Supplements Do Anything for Weight Loss, Large Review Finds

No Strong Evidence Supplements Do Anything for Weight Loss, Large Review Finds
A shopper browsing through an array of vitamin supplements at a GNC vitamin store on February 19, 2003 in New York City. (Photo: Chris Hondros, Getty Images)

Dietary supplements don’t do much to help people lose weight — that’s the verdict from a large new review published Wednesday. The review found little high-quality evidence from studies trying to test these supplements’ claimed benefits and only inconsistent evidence that some supplements could possibly offer a small boost in losing weight.

Plenty of people have turned to dietary supplements to help them reach their weight goals. According to survey data, about a third of American adults trying to lose weight have used supplements in the past. Estimates range, but the weight loss supplement market is also thought to bring in billions of dollars annually.

Unfortunately, supplements don’t undergo the same level of scrutiny before they reach the public as drugs approved by the Food and Drug Administration do, and many studies have suggested that their health benefits aren’t as potent as advertised. This new research, published in the July 2021 issue of the journal Obesity, seems to show the same is true when it comes to weight loss.

The researchers analysed 315 clinical trials involving supplements or acupuncture therapy being used for weight loss. Generally, though, these trials were deemed to be low quality, since they often had small sample sizes, a high risk of potential bias (one example of bias being that people would know if they were taking the supplement, compared to a blinded trial in which subjects don’t know what treatment they receive), and were otherwise poorly designed.

Ultimately, the group singled out 52 studies as having a low risk of bias and sufficient evidence to support the effectiveness of a particular supplement. Out of these, only 16 reported results that suggested at least a modest improvement in weight loss before and after the trial. Some of the supplements that showed these benefits, though not always consistently, were green tea, conjugated linoleic acid, and caffeine. But even these improvements ranged widely, from a low of 0.3 kilograms (over half a pound) to a high of 4.93 kilograms (just over 5 kg) found in treatment groups.

“Despite there being a number of studies evaluating dietary supplements and alternative therapies for weight loss, this review does not support strong, high-quality evidence of the efficacy of any of the products,” the authors wrote.

To be fair, few interventions have ever really proven all that effective at helping people achieve long term weight loss. Regular exercise improves people’s health tremendously but does little for weight loss on its own. Dieting may work initially, but it’s very difficult for most people to sustain the restrictive changes in their diet that cause this weight loss over time. Bariatric surgery does consistently lead to a significant amount of sustained weight loss, but not for everyone, and it’s a costly, life-altering treatment. And, up until recently, no FDA-approved drugs were shown to provide more than a small bump in improved weight loss outcomes.

Supplements, though, are perhaps the least helpful way to lose weight, since they’re not only unproven but largely unregulated. Indeed, they’re commonly found to contain hidden and potentially harmful ingredients that could interact badly with other drugs users may be taking. In an accompanying editorial by researchers from the Obesity Society’s Clinical Committee, the authors argue that doctors should be aware of their overall lack of safety and the little evidence behind their use for weight loss; they’re also pushing for agencies like the FDA to do more to rein them in.

“Regulatory authorities should protect consumers by ensuring accurate and safe marketing claims and preventing promotion of unproven and potentially unsafe products and claims,” they wrote.