Obesity is a global public health threat. This study investigated relationships between heavy metal exposure, gut microbiome composition, and obesity by comparing obese individuals and healthy controls. Heavy metal levels in stool were assessed via ICP‐MS, microbiome profiling via 16S rRNA sequencing, and biochemical parameters from blood. Key results showed obese individuals had significantly elevated FBS, cholesterol, triglycerides, LDL, VLDL, liver enzymes, and lymphocytes (p < 0.05). ICP‐MS revealed higher stool concentrations of Cd, Zn, Fe, Mn, and P, and lower levels of Ba, V, W, Ti, Ge, Nd, and S in obese subjects (p < 0.05). Although Bifidobacteriaceae, Ruminococcaceae, and Coriobacteriaceae were abundant across all groups with no significant difference in abundance (p > 0.05) or alpha diversity (p = 0.3), beta diversity revealed significant phylogenetic differences between controls and obese/lean groups (p < 0.0001). Specific correlations were identified: Bifidobacteriaceae abundance negatively correlated with cadmium (r = −0.6629, p = 0.0051) and fasting blood glucose (r = −0.61, p = 0.021). BMI positively correlated with Bacteroides abundance (r = 0.5851, p = 0.0190) and negatively with HDL (r = −0.68, p = 0.007). Iron negatively correlated with total cholesterol (r = −0.62, p = 0.019). Coriobacteriaceae abundance positively correlated with manganese (r = 0.55, p = 0.040) and ALT (r = 0.56, p = 0.039). Ruminococcaceae negatively correlated with triglyceride and VLDL (r = −0.55, p = 0.041). These findings suggest elevated heavy metal excretion links environmental exposure to obesity. Phylogenetic microbial differences, despite similar abundance, highlight environmental influences on gut microbiota, underscoring the importance of investigating environmental factors in metabolic health.
