The effect of green-coffee extract supplementation on obesity: A systematic review and dose-response meta-analysis of randomized controlled trials

Background: Given that the most recent systematic review investigating Green-Coffee Extract (GCE) as a weight loss facilitator was nearly a decade ago and that the authors reported there no consensus on the effect of GCE/CGA (Chlorogenic acids) on body composition indices, a comprehensive systematic review and dose-response meta-analysis of all available randomized controlled trial (RCTs) was undertaken to examine the effect of GCE and CGA intervention on body weight (BW), body mass index (BMI) and waist circumference (WC) in adults. Methods: We conducted a systematic search of all available randomized controlled trials (RCTs) performed up to June 2019 in the following electronic databases: PubMed, Scopus and Google Scholar. RCTs that investigated the effect GCE/CGA Supplementation on BW, BMI and WC in adults were included for final analysis. The pooled weight mean difference (WMD) of included studies was estimated using a random-effects model. Results: A total of 13 articles with 16 RCTs were included in the meta-analysis. Results revealed significant reduction in BMI (WMD: - 0.403 kg/m(2), 95% CI: - 0.800, - 0.005, p = 0.047) and no significant change in BW (WMD: - 0.585 kg, 95% CI: - 1.498, 0.329, p = 0.210) and WC (WMD: - 0.847 cm, 95% CI: - 1.764, 0.071, p = 0.070). In the subgroup analysis, studies that were conducted on baseline BMI >= 25 kg/m(2) revealed a significant greater reduction in body weight and BMI than those performed on baseline BMI <25 kg/m(2). Moreover, short supplementation periods of less than 4 weeks had no effect. Conclusion: The results of current meta-analysis study support the use of GCE supplementation for the improvement of obesity indices, with sub-group analysis highlighting greater improvements in individuals with a starting BMI >= 25 kg/m(2).