Background <p>Obesity is a global epidemic and multifactorial disease caused by alcohol consumption, a sedentary lifestyle, and genetic and environmental factors. Analyses of gut microbial diversity in obese individuals have been conducted earlier. Unlike non-alcoholic fatty liver diseases, the mechanistic insights into the role of gut microbiota in the development of obesity remain poorly understood. Deciphering the mechanism underlying bacterial-induced obesity will help in targeted therapeutic approaches. We demonstrated bacteriophage therapy as a new offering to treat obesity and hepatic steatosis.</p> Methods <p>Stool samples from the non-alcoholic obese cohort (BMI &gt; 27 kgm⁻²) were cultured to analyze gut microbiota. Bacteria were grouped into clusters based on whole-genome-based genotyping. The most predominant, high alcohol-producing <i>E. coli</i> strain, GNBHU03 (ECGNBHU03), was selected for further studies. Genome sequencing and subsequent analyses were performed to understand the pathogenesis of ECGNBHU03. Further, an obesity model was developed by administering ECGNBHU03 into male mice. The induced obesity and liver steatosis were evaluated using weight measurements, blood biochemical tests, and changes in the liver histology. Cocktails of three ECGNBHU03-specific bacteriophages were used to eradicate the ECGNBHU03; blood biochemical tests and histological studies evaluated the effect of eradicating ECGNBHU03 from the gut.</p> Results <p><i>Escherichia coli</i> was predominantly detected in the feces of 95.65% of individuals compared to the control group (non-alcoholic healthy cohort with BMI 18.5–22.9 kgm⁻²). Whole-genome-based genotyping generated five groups. The high alcohol-producing <i>Escherichia coli</i> strain, GNBHU03, was enriched in the gut microbiota of non-alcoholic obese individuals. Genomic analyses showed that GNBHU03 harbours different virulence genes, specifically <i>lpf</i> and <i>hlyE</i> associated with increased intestinal colonization and permeability. In ECGNBHU03-fed mice, colonization with ECGNBHU03 induced obesity, hepatic steatosis, and systemic inflammation, evident by elevated serum aminotransferases, endotoxins, pro-inflammatory cytokines, triglycerides, cholesterol levels, and liver steatosis. Further, targeted bacteriophage therapy effectively eradicated strain ECGNBHU03, reversing obesity and hepatic steatosis.</p> Conclusions <p>This study highlights the complexity of obesity’s etiology and, for the first time, provides mechanistic insights into obesity and liver dysfunction caused by the high ethanol-producing <i>E. coli</i> strain GNBHU03. Notably, targeted bacteriophage therapy could be a promising strategy to mitigate obesity, offering a novel approach to obesity treatment.</p>