This study investigates the relationship between gut microbiota composition and its implications on obesity and athletic adolescents. We compared the gut microbiota between twenty athletes (Group A) and twenty overweight or obese adolescents (Group B) by high-throughput sequencing of bacterial rRNA genes. The results showed a significant reduction in microbial richness in Group B compared to Group A, along with significant differences in microbial community structures. Notably, athletes displayed a greater microbial diversity, potentially contributing to better metabolic health outcomes. In contrast, the obese group exhibited a dominance of Bacteroides, which correlates with higher body mass index (BMI) and may influence obesity-related health issues.