Obesity is a growing global health challenge, closely linked to chronic low-grade inflammation. This persistent, low-intensity immune response contributes to the development of metabolic, cardiovascular, and cancer-related diseases. A key player in this process is the gut microbiota. Dysbiosis, an imbalance in gut bacterial composition, disrupts metabolic function, weakens the intestinal barrier, and promotes the production of pro-inflammatory cytokines. In people with obesity, gut microbial diversity is reduced, and the ratio of beneficial to harmful bacteria shifts, affecting lipid metabolism and immune balance. Short-chain fatty acids, produced by gut bacteria, help maintain gut integrity and reduce inflammation. Butyrate, a major SCFA, also improves insulin sensitivity and may support obesity treatment. Diet plays a central role in shaping the gut microbiome. Western diets tend to promote dysbiosis and inflammation, while Mediterranean-style diets encourage the growth of beneficial bacteria. Targeted modulation of the microbiota through diet, probiotics, or medication emerges as a promising strategy for preventing and managing obesity.