[Obesity and genetics: advances in understanding genetic factors and their clinical impact]

Obesity is a complex chronic disease involving physiological, behavioural, and environmental factors, with a key role played by the gut microbiota. A narrative review was conducted using PubMed, Scopus, Web of Science, and EMBASE databases, including books, clinical practice guidelines, meta-analyses, observational studies, and reviews published in English or Spanish. Animal studies and publications prior to 2014 were excluded. A total of 15,074 publications were identified, of which 127 were selected for full-text review. Key findings include the lack of consensus on obesity classification, phenotypic variability that cannot be solely explained by genetic or epigenetic factors, and differences between monogenic, syndromic, and polygenic obesity. The implementation of genomic and epigenetic tools, such as biomarkers and personalized nutritional strategies, is crucial for precision medicine in obesity management. However, further research is needed for its widespread clinical application.