Metabolic syndrome is widespread and negatively impacts healthy longevity but takes years to study in mammalian models, delaying translational applications. To address this, we characterized the unique polygenic “Titan” mouse (110 grams average) with a healthy lifespan of only 4 months that was generated by 45 years of breeding selection. Titan mice displayed increased plasma leptin, insulin, IL-6 and fasting triglycerides. Also, pancreatic fat cell accumulation and thymic medullary hyperplasia were detected in Titan animals. Liver transcriptome and proteome analysis demonstrated alterations in lipid metabolism, the methionine cycle, and cytochrome P450 regulation in Titan mice. Late dietary intervention in Titan mice reduced fat content and improved expression of genes involved in lipid synthesis and cytochrome P450 detoxification, altering the abundance of metabolites, including malonyl-CoA and dimethylglycine. Strikingly, late dietary intervention at 3 months of age almost doubled the healthy lifespan of Titan mice. This powerful model of metabolic disorders, systemic inflammation, and early aging will enable to provide uniquely rapid results for translational intervention.