Surgery as Metabolic Therapy: Expanding the Role of Gastrointestinal Surgery Beyond Anatomical Reconstruction

Gastrointestinal surgery comprises procedures used to treat diseases and injuries of the digestive tract. Evidence now shows that some gastrointestinal procedures are also systemic metabolic interventions. Bariatric and metabolic surgery intentionally treats obesity and associated metabolic disease and can improve type 2 diabetes, metabolic dysfunction-associated steatotic liver disease, and cardiometabolic risk, sometimes before substantial weight loss occurs. Other procedures, including hepatectomy, pancreatic resection, and bowel resection, are generally performed for non-metabolic indications; their metabolic consequences may be adaptive, neutral, or adverse, including pancreatogenic diabetes and intestinal failure. This narrative review examines how major gastrointestinal operations affect whole-body metabolism and discusses metabolic phenotyping for personalized patient selection, preoperative optimization, postoperative management, and long-term monitoring. The review highlights bariatric and metabolic surgery as the reference model while distinguishing its established therapeutic effects from the metabolic consequences of other resections. It proposes that surgery should be considered both a correction of anatomy and a perturbation of physiology, enabling plans that preserve structural integrity, support metabolic adaptation, and limit metabolic harm.