The Gut Microbiome and Pediatric Obesity: A Systematic Review and Meta-Analysis of Observational Studies

Abstract

Background:
Pediatric obesity has emerged as a global health crisis, affecting over 18% of children and adolescents worldwide. Emerging evidence suggests that gut microbiota composition and diversity may significantly influence obesity risk through mechanisms related to energy harvest, inflammation, and insulin resistance. This systematic review and meta-analysis aimed to evaluate the association between gut microbiota profiles and pediatric obesity based on observational studies.

Methods:
A comprehensive search of PubMed, Scopus, and Web of Science databases was conducted for observational studies published between 2000 and 2024. Eligible studies assessed the gut microbiota in children aged 0–18 years, comparing obese/overweight groups to healthy controls. Data were extracted and pooled using random-effects meta-analysis. Primary outcomes included bacterial diversity (α-diversity) and relative abundance of key phyla and genera. Secondary outcomes included effect sizes (odds ratios and standardized mean differences), as well as subgroup analyses based on region, age, and sequencing methods.

Results:
Thirty-seven studies (n = 4,812 children) met inclusion criteria. Children with obesity exhibited significantly lower α-diversity (SMD = –0.48, 95% CI: –0.62 to –0.35, p < 0.001) and altered microbial composition, with higher abundance of Firmicutes and lower Bacteroidetes (Firmicutes/Bacteroidetes ratio: OR = 1.86, 95% CI: 1.41–2.44). Specific genera such as Lactobacillus and Prevotella were more prevalent in obese cohorts. Area under the curve (AUC) values for microbiota-based prediction models ranged from 0.71 to 0.84 across studies. Heterogeneity was moderate (I² = 58%). No major publication bias was detected.

Conclusion:
Altered gut microbiota is significantly associated with pediatric obesity. Reduced microbial diversity and specific taxonomic shifts may serve as early indicators of metabolic dysregulation. Microbiome-based diagnostics and interventions could become valuable tools in obesity prevention and management in children