Study Shows No Significant Evidence for the Efficacy of Herbal, Dietary Weight Loss Supplements


An analysis of randomized placebo-controlled trials suggests that the use of herbal and dietary supplements for weight loss cannot be justified based on the available evidence. Presented at the European Congress on Obesity, the analysis includes data from 121 trials with nearly 10,000 adult participants.

The findings indicate that although some herbal and dietary supplements show statistically greater weight loss than placebo, it is not enough to benefit health, according to the study authors. Further, the investigators call for more research into their long-term safety of these supplements.

“Over-the-counter herbal and dietary supplements promoted for weight loss are increasingly popular, but unlike pharmaceutical drugs, clinical evidence for their safety and effectiveness is not required before they hit the market”, said dietitian Erica Bessell, PhD candidate at the University of Sydney, in a press release. “Our rigorous assessment of the best available evidence finds that there is insufficient evidence to recommend these supplements for weight loss. Even though most supplements appear safe for short term consumption, they are not going to provide weight loss that is clinically meaningful.”

The researchers did a systematic review of 54 randomized trials comparing the effect of herbal supplements to placebo on weight loss up to August 2018, followed by a systematic review up to December 2019 of 67 randomized trials. Of the 14 supplements analyzed, only 4 resulted in a statistically significant increase in weight loss, and none resulted in clinically significant weight loss (5.5 lbs or greater).

Some dietary supplements, including modified cellulose—plant fibre that expands in the stomach to induce a feeling of fullness—and blood orange juice extract, showed promising results. However, these were only investigated in 1 trial and more evidence is required before recommending them for weight loss, according to the study authors.

“Herbal and dietary supplements might seem like a quick-fix solution to weight problems, but people need to be aware of how little we actually know about them,” Bessell said, in the press release. “Very few high-quality studies have been done on some supplements with little data on long-term effectiveness. What's more, many trials are small and poorly designed, and some don't report on the composition of the supplements being investigated. The tremendous growth in the industry and popularity of these products underscores the urgency for conducting larger, more rigorous studies to have reasonable assurance of their safety and effectiveness for weight loss.”


Most comprehensive studies to date find 'insufficient evidence' to support herbal and dietary supplements for weight loss [news release]. EurekAlert; May 8, 2021. Accessed May 10, 2021.

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