INS and injury: This advantage endows FMR with dual capacity: elevated FMR captures adipose‐driven metabolic dysfunction (where visceral fat deposition, releases free fatty acids that induce hepatic insulin resistance, increasing risks of hyperglycemia‐related infections and renal injury) and muscle‐mediated reserve depletion (where low muscle mass, limits amino acid availability for acute‐phase protein synthesis, impairing stress response), thus more accurately predicting postoperative systemic complications following abdominal surgery [18, 19].