Background: Overweight and obesity are major health concerns. The impact of ginger on weight has been studied. In the present systematic review and dose-response meta-analysis we aim to sum up the findings from randomized controlled trials (RCTs) on the effect of ginger on various weight measurements/indices. 

Methods: Several databases (PubMed, Scopus, Web of Science Core Collection, and Google Scholar) were comprehensively searched. Relevant studies were selected using defined criteria. 

Outcomes included: body weight (BW), body mass index (BMI), waist circumference (WC), body fat percentage (BFP), adiponectin and leptin. Weighted mean difference (WMD) and confidence interval (CI) were reported. Subgroup analysis was carried out. Linear and non-linear associations, based on dosage and duration of interventions, were investigated. 

Results: Thirty-six RCTs were included. Ginger supplementation significantly improved WC (WMD: − 0.65 cm, 95 % CI: − 1.07, − 0.24), BFP (WMD: − 1.49 %, 95 % CI: − 2.65, − 0.32), and serum adiponectin levels (WMD = 0.84 μg/mL; 95 % CI: 0.01). Other measurements were not improved by the intervention. An inverse, linear association was found between the duration of intervention and changes in BW (BW: coefficient = -0.471, P = 0.001). Also, a non-linear direct association was observed between ginger dosages and WC (P-nonlinearity = 0.023).

Conclusions: Ginger supplementation does not seem effective in improving major measurements/indices of weight, including body weight and BMI. However, ameliorations in other measurements of local adiposity, findings from subgroup analyses, and investigations of linear and non-linear association on dosage and duration, indicate that further studies with longer intervention periods are needed to make a conclusive decision.