Reframing obesity through the gut microbiota: functional dysbiosis and metabolic disease

PURPOSE OF REVIEW: Obesity and its metabolic complications remain major global health challenges. Beyond excess caloric intake, emerging evidence implicates diet-induced gut microbiota dysfunction as a modulator of metabolic homeostasis. This review examines recent advances in understanding how functional alterations of the gut microbiota contribute to obesity pathogenesis. RECENT FINDINGS: Current data indicate that obesity is characterized less by specific microbial taxa and more by disruption of key microbial functions. Diet-induced dysbiosis alters short-chain fatty acid production, bile acid metabolism, tryptophan-derived signaling, and intestinal barrier integrity. These changes promote metabolic endotoxemia, impair enteroendocrine hormone secretion, and disrupt gut-brain and gut-liver communication, contributing to adipose tissue inflammation, hepatic steatosis, and insulin resistance. Experimental and clinical studies further suggest that microbiota-targeted interventions, including dietary fiber enrichment, prebiotics, synbiotics, and fecal microbiota transplantation, can partially restore microbial metabolic function and improve selected metabolic outcomes. SUMMARY: Obesity is increasingly conceptualized as a state of diet-driven functional gut microbiota disruption. Targeting microbial metabolic pathways rather than individual taxa may offer a promising adjunctive strategy to complement established therapies for obesity-related metabolic disease.