Effectiveness of herbal medicines for weight loss: a systematic review and meta-analysis of randomised controlled trials.

The complementary medicines industry provides many herbal medicines that purportedly assist in weight loss, often with unclear evidence supporting efficacy and safety. To update available evidence, a systematic review and meta-analysis of herbal medicines for weight loss was conducted.Four electronic databases (Medline, Embase, Cinahl and Web of Science) were searched from inception until August 2018. Fifty-four randomised placebo-controlled trials of healthy adults with overweight or obesity were identified. Meta-analyses were conducted for herbal medicines with ≥4 studies available. Weight differences of ≥2.5 kg were considered clinically significant.As a single agent, only Phaseolus vulgaris resulted in a statistically significant weight loss compared to placebo, though not considered clinically significant. No effect was seen for Camellia sinensis or Garcinia cambogia. Statistically, but not clinically, significant differences were observed for combination preparations containing Camellia sinensis, Phaseolus vulgaris or Ephedra sinica. Of the herbal medicines trialled in ≤3 randomised controlled trials, statistically and clinically significant weight loss compared to placebo was reported for Irvingia gabonensis, Cissus quadrangularis, and Sphaeranthus indicus combined with Garcinia mangostana, among others, but these findings should be interpreted cautiously due to the small number of studies, generally poor methodological quality and poor reporting of herbal medicine interventions. Most appeared safe for consumption over the short duration of the studies (commonly ≤12 weeks). Some warrant further investigation to determine effect size, dosage and long-term safety.There is currently insufficient evidence to recommend any of these herbal medicines for weight loss. This article is protected by copyright. All rights reserved.