Comparative Gut Microbiota Profiling of Obese and Normal-Weight Indian Adults Using 16S rRNA Sequencing

Background: Obesity rates are rising globally, placing a significant strain on individuals, society, and economies. The gut microbiota (GM) plays a pivotal role in the development of obesity. Many studies have identified differences in GM composition between obese and normal-weight people worldwide. However, there is limited data on the GM profiles of obese and control Indian individuals. Methods: Fecal samples from 20 participants (10 obese, 10 control) underwent 16S rRNA gene sequencing. Anthropometric analysis confirmed significant differences in weight and BMI, with no significant variance in age or height. Taxonomic profiling and diversity indices (Chao1, Shannon, Simpson) were evaluated using the NCBI database. Results: Sequencing identified 1,359 Operational Taxonomic Units. The obese cohort exhibited an elevated Firmicutes-to-Bacteroidetes (F/B) ratio, with Firmicutes increasing to 53.78% and Bacteroidetes decreasing to 25.54%. A significant reduction in Fusobacteria was observed in the Ob group (p=0.034). Seven species were significantly enriched in obese subjects: Bifidobacterium catenulatum (p=0.031), Anaerostipes hadrus (p=0.014), Eggerthella lenta (p=0.032), Bifidobacterium bifidum (p=0.037), Clostridium butyricum (p=0.012), Phascolarctobacterium sp. (p=0.046), and Alistipes onderdonkii (p=0.033) . Rarefaction curves showed higher species richness in the control group, whereas PCA plots indicated greater community similarity (lower beta diversity) in the obese group. Conclusion: Obesity is associated with distinct microbial dysbiosis, characterized by a significant loss of Fusobacteria and an enrichment of SCFA-producing species. These specific taxonomic shifts, rather than broad diversity indices, provide a more sensitive signature for metabolic changes associated with obesity, supporting the “energy harvest” hypothesis.