bile acids

Background: Obesity is a chronic endocrine-metabolic disease characterized by excess adiposity, metabolic inflammation and a high burden of cardiometabolic complications. The gut microbiota has emerged as a biologically plausible determinant of obesity because it regulates energy harvest, gut barrier integrity, immune signaling, bile acid metabolism and appetite-related neuroendocrine pathways. Methods: A structured literature search was conducted in PubMed/MEDLINE, ScienceDirect and Google Scholar for publications from 2000 to 2024 using English and French terms related to obesity, gut microbiota, dysbiosis, inflammation, probiotics, prebiotics, fecal microbiota transplantation, microbiota-targeted therapy and energy metabolism. Systematic reviews, meta- analyses, randomized trials, observational studies and mechanistic investigations were eligible when they addressed microbiota composition, obesity-related mechanisms or microbiome-based therapeutic strategies. Results: Seventy-two records were initially identified. After duplicate removal, 40 records were screened and 26 full-text publications were retained for qualitative synthesis. Obesity was frequently associated with reduced microbial richness, altered Firmicutes and Bacteroidetes profiles, enrichment of inflammatory taxa and depletion of potentially beneficial organisms such as Akkermansia muciniphila, Bifidobacterium and Faecalibacterium prausnitzii. The principal mechanisms involve short-chain fatty acid signaling, bile acid transformation, metabolic endotoxemia, low-grade inflammation, altered intestinal permeability, adipose-tissue dysfunction and gut-brain axis dysregulation. Dietary strategies, probiotics, prebiotics, next-generation probiotics and fecal microbiota transplantation show therapeutic potential, although clinical efficacy remains heterogeneous. Conclusion: The gut microbiota is not merely an associated biomarker of obesity but a dynamic metabolic interface that may influence disease expression and therapeutic response. Microbiome- targeted approaches are promising for future precision obesity care, but routine clinical implementation requires standardized, adequately powered and mechanistically informed human trials.