Ginger intervention on body weight and body composition in adults: a GRADE-assessed systematic review and dose-response meta-analysis of 27 randomized controlled trials

CONTEXT: Ginger consumption may have an inverse relationship with obesity and metabolic syndrome parameters; however, clinical trials have reported contradictory results. OBJECTIVE: To systematically review and analyze randomized controlled trials (RCTs) assessing the effects of ginger on body weight and body composition parameters. METHODS: Databases were searched for appropriate articles up to August 20, 2022. All selected RCTs investigated the impact of ginger on glycemic indices in adults. A random effects model was used to conduct a meta-analysis, and heterogeneity was assessed using the I2 statistic. Net changes in body weight, body mass index (BMI), waist circumference (WC), and percent body fat were used to calculate the effect size, which was reported as a weighted mean difference (WMD) and 95% confidence intervals (CIs). The risk of bias was assessed. RESULTS: A total of 27 RCTs involving 1309 participants were included. The certainty in the evidence was very low for WC and BMI, and low for body weight and percent body fat as assessed by the GRADE evidence profiles. The meta-analysis showed a significant association between ginger supplementation and a reduction in body weight (WMD, -1.52 kg; 95%CI, -2.37, -0.66; P < 0.001), BMI (WMD, -0.58 kg/m2; 95%CI, -0.87, -0.30; P < 0.001), WC (WMD, -1.04 cm; 95%CI: -1.93, -0.15; P = 0.021), and percent body fat consumption (WMD, -0.87%; 95%CI, -1.71, -0.03; P = 0.042). The results of the nonlinear dose-response analysis showed a significant association between the ginger dose with body weight (Pnonlinearity = 0.019) and WC (Pnonlinearity = 0.042). The effective dose of ginger intervention for body mass reduction was determined to be 2 g/d in dose-response analysis. The duration of ginger intervention had a significant nonlinear relationship with body weight (Pnonlinearity = 0.028) with an effective duration of longer than 8 weeks. CONCLUSIONS: Our findings provide evidence that ginger consumption may significantly affect body composition parameters nonlinearly. More, well-constructed RCTs are needed.