Recent Insights Into Circulating Adipokines in Obesity: Systematic Review and Meta-Analysis

Adipokines are dysregulated in obesity and exacerbate proinflammatory conditions. Although several studies have investigated adipokine levels in obesity, their findings have been inconsistent, leaving the precise nature of these alterations uncertain. This systematic review and meta-analysis aimed to provide an updated overview of circulating adipokines, particularly adiponectin, leptin, fibroblast growth factor 21 (FGF21), growth differentiation factor 15 (GDF15), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the context of obesity.

This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and PROSPERO registration (CRD42024525103). PubMed/MEDLINE, Scopus, and Journal of Clinical Investigation databases were searched from inception to August 25, 2025. Eligible observational studies were assessed using the ROBINS-I and GRADE frameworks. Standardized mean differences (SMDs) were calculated using a random-effects model.

From 2378 records, 30 and 16 studies were included in the review and meta-analysis, respectively. Adiponectin levels were significantly lower in persons with obesity than in those with normal weight (p = 0.007). Conversely, leptin, TNF-α, and FGF21 levels were significantly higher in persons with obesity (p < 0.01). No significant differences were found for GDF15 (p = 0.62) and IL-6 (p = 0.17).

Adiponectin, leptin, TNF-α, and FGF21 show consistent directionality and may serve as robust biomarkers in obesity-related risk profiling. Conversely, GDF15 and IL-6 exhibit context-dependent variability. Further prospective cohort studies are warranted to better understand these adipokines, as persons with normal weight may still be at a high risk of cardiometabolic diseases.