Population scale analysis reveals gut microbiome diversity and functional shifts linked to obesity

This study investigated the relationship between the gut microbiota and two obesity indicators, body mass index (BMI) and waist-hip ratio (WHR) in a well-phenotyped random population sample of 5846 participants. Associations were tested using multivariable-adjusted linear models and validated for BMI in an external cohort of 275 individuals. First, alpha diversity measured by Shannon was inversely associated with obesity but not observed species richness. Second, BMI was significantly associated with beta diversity (Bray Curtis) although there was no obvious clustering. Third, Bacteroidota:Firmicutes ratio was not associated with BMI or WHR. Finally, our study revealed that the gut microbiome of individuals with obesity was enriched with inflammation-associated species involved in lipid metabolism and pathways related to folate precursor, membrane lipid proteins and tRNA charging. Lean individuals were enriched in bacteria linked to cellulose breakdown.