Changes in Fat and Muscle Tissue Function and Their Impact on Metabolic Health After Bariatric Surgery

This prospective, single-center observational cohort study aims to explore the relationship between skeletal muscle quality, fat distribution, and metabolic health in Chinese patients with obesity, and to evaluate how bariatric surgery influences these parameters. A total of 120 participants will be enrolled, including 60 patients undergoing bariatric surgery and 60 age- and sex-matched healthy controls. The study involves cross-sectional comparisons of ectopic fat and muscle composition, as well as longitudinal follow-up of surgical patients at multiple time points up to 5 years postoperatively. MRI will be used to quantify regional fat and muscle composition, while metabolic parameters, inflammatory markers, and gut microbiota profiles will also be assessed. Primary outcomes include skeletal muscle mass and fat infiltration, visceral and subcutaneous fat volumes, and changes in insulin resistance. This study seeks to clarify the mechanisms by which bariatric surgery improves metabolic function and to identify early changes in muscle-fat composition that may predict long-term metabolic outcomes.