A new meta-study from a team of Australian researchers has reviewed over 50 placebo-controlled trials from the last 20 years testing the efficacy of herbal medicines for weight loss. The results reveal herbal supplements are largely ineffective in aiding weight loss, and the senior author on the study suggests they are essentially a “waste of money.”

The newly published meta-analysis presents the first systematic review of research investigating herbal medicines and weight loss in nearly 20 years. The study collected data from 54 randomized, placebo-controlled trials looking at the efficacy of herbal medicines for weight loss.

The analysis only focused on herbal medicines that consisted of whole plants, or combinations of whole plants. So, weight loss concoctions including plant oils, or fiber and protein supplements were not included.

“The problem with supplements is that unlike pharmaceutical drugs, clinical evidence is not required before they are made available to the public in supermarkets or chemists,” explains Nick Fuller, senior author on the new study.

The meta-study found that many of the trials reviewed published statistically significant, but not clinically significant, results. The threshold for clinical significance for this meta-study was set at a weight loss equal to or greater than 2.5 kg (5.5 lb) by the end point of the trial.

“This finding suggests there is insufficient evidence to recommend any of these herbal medicines for the treatment of weight loss,” says Fuller. “Furthermore, many studies had poor research methods or reporting and even though most supplements appear safe for short-term consumption, they are expensive and are not going to provide a weight loss that is clinically meaningful.”

In an interview with ABC News Australia, Fuller suggests these herbal weight loss medicines are largely a “waste of money.” He notes there are effective alternative and herbal medicines around, however, this particular focus on weight loss herbal medicines found no evidence to suggest they work, despite several decades of clinical study.

The analysis identified four herbs in particular that commonly appeared as weight loss medicines, either alone or in formulations: Camellia sinensis (green tea), Garcinia cambogia (Malabar tamarind), Phaseolus vulgaris (white kidney bean) and Ephedra sinica.

Green tea was the most clinically studied supplement, having been investigated in 12 clinical trials. Seven of those trials examined green tea alone as a herbal supplement for weight loss and the meta-analysis of those seven trials revealed no weight loss benefit compared to placebo.

Malabar tamarind was the second most commonly investigated herbal supplement, examined in 11 clinical trials. Methodological errors and a high risk of bias was found in 10 of those 11 trials. Despite the bias and errors noted, the metastudy found Malabar tamarind to have a non-significant effect on weight loss, both when administered as a single herb and as an element in more complex supplements.

Ultimately, while the metastudy does suggest a number of the herbal medicines reviewed did result in some small level of weight loss compared to placebo, they could not be considered clinically meaningful. So essentially, you may be able to lose an additional two or three pounds by taking these herbal medicines for a few months, but these are essentially insignificant levels of weight loss and not worth the money spent.

The new research was published in the journal Diabetes, Obesity and Metabolism.

Source: University of Sydney