Gut Microbiome Responses to Nutritional and Lifestyle Interventions in Pediatric Obesity: A Systematic Review Toward Precision Nutrition.

Background: Childhood obesity is increasingly associated with gut microbiome dysbiosis. This systematic review (PROSPERO CRD420251131354) evaluates evidence from studies published between 2020 and 2026 assessing how nutritional and lifestyle interventions influence gut microbiota in children with obesity. Methods: A systematic search of PubMed, EMBASE and EBSCO identified 21 interventional studies involving children aged 5-18 years with obesity, with the last search conducted in April 2026. Interventions comprised prebiotics, probiotics, synbiotics, postbiotics, high-fiber diets, calorie-restricted dietary approaches, and lifestyle modifications such as physical activity. Microbiome outcomes were analyzed using 16S rRNA sequencing, quantitative real-time polymerase chain reaction (qPCR), or metagenomics. Risk of bias was evaluated using the RoB 2 and ROBINS-I (version 2) tools. Due to substantial heterogeneity in study design, participant characteristics, intervention types, and analytical methods, a meta-analysis was not feasible. Results: Across 21 studies, nutritional interventions included measurable but heterogeneous alterations in gut microbiome composition. Inulin supplementation was associated with a significant increase in alpha diversity and with higher relative abundances of Bifidobacterium, Blautia, Megasphaera, Subdoligranulum, and Eubacterium coprostanoligenes. Synbiotic supplementation increased Prevotella and Dialister and reduced the Firmicutes/Bacteroidetes ratio. High-fiber dietary interventions increased Faecalibacterium, Bifidobacterium, and Clostridium, while reducing Bacteroides, and were associated with shifts in metabolic pathways related to carbohydrate, lipid, and nucleotide metabolism. Calorie-restricted diets and combined diet-exercise interventions increased beneficial taxa such as Akkermansia muciniphila, improved microbial diversity, and correlated with favorable metabolic and anthropometric outcomes. Overall, nutritional and lifestyle interventions in pediatric obesity were associated with taxon-specific and context-dependent microbiome changes, rather than uniform restructuring. Conclusions: Nutritional interventions can modulate gut microbiota diversity, composition, and predicted function in pediatric obesity; however, the observed effects vary substantially across studies. The limited number of trials, small sample sizes, and methodological heterogeneity underscore the need for larger, standardized studies to better define clinical and therapeutic implications.