Previous studies have found reduced concentrations of both leptin and resistin after glucagon-like peptide-1 receptor agonist (GLP-1 RA) treatment; however, the evidence in this field is inconclusive. Therefore, the aim of this meta-analysis of randomized controlled trials was to evaluate the effect of GLP-1 RA on both leptin and resistin levels.The present systematic review and meta-analysis included randomized controlled trials investigating the effect of GLP-1 RA on leptin and resistin concentrations. For this, PubMed-MEDLINE, Scopus, Web of Science, ClinicalTrials.gov, and Google Scholar databases were searched. A random-effects model and a sensitivity analysis were performed for meta-analysis.Meta-analysis of 13 randomized controlled trials comprising 1,025 subjects indicated that administration of GLP-1 RA significantly decreases leptin (WMD: -4.85 ng/mL, 95% CI: -9.32, -0.38, p = 0.03) and resistin (WMD: -1.40 ng/mL, 95% CI: -2.78, -0.01, p = 0.05) serum levels. However, the effect size was sensitive to four studies for both leptin and resistin concentrations.The results of this meta-analysis of randomized controlled trials suggest that GLP-1 RA therapy reduces both leptin and resistin levels.Copyright © 2021 Elsevier B.V. All rights reserved.