The effects of capsaicin intake on weight loss among overweight and obese subjects: a systematic review and meta-analysis of randomised controlled trials

Animal studies have shown that capsaicin plays a positive role in weight management. However, the results in human research are controversial. Therefore, the present systematic review and meta-analysis aimed to evaluate the effect of capsaicin on weight loss in adults. We searched PubMed, Embase, China Biomedical Literature Database (CBM), Cochrane library and clinical registration centre, identifying all randomised controlled trials (RCT) published in English and Chinese to 3 May 2022. A random-effect model was used to calculate the weighted mean difference (WMD) and 95 % CI. Heterogeneity between studies was assessed by the Cochran Q statistic and I-squared tests (I 2 ). Statistical analyses were performed using STATA version 15.1. P-values < 0·05 were considered as statistically significant. From 2377 retrieved studies, fifteen studies were finally included in the meta-analyses. Fifteen RCT with 762 individuals were included in our meta-analysis. Compared with the control group, the supplementation of capsaicin resulted in significant reduction on BMI (WMD: −0·25 kg/m2, 95 % CI = –0·35, –0·15 kg/m2, P < 0·05), body weight (BW) (WMD: −0·51 kg, 95 % CI = –0·86, –0·15 kg, P < 0·05) and waist circumference (WC) (WMD: −1·12 cm, 95 % CI = –2·00, –0·24 cm, P < 0·05). We found no detrimental effect of capsaicin on waist-to-hip ratio (WMD: −0·05, 95 % CI = –0·17, 0·06, P > 0·05). The current meta-analysis suggests that capsaicin supplementation may have rather modest effects in reducing BMI, BW and WC for overweight or obese individuals.