The evolution of metabolic/bariatric surgery.

Metabolic surgery is defined as "the operative manipulation of a normal organ or organ system to achieve a biological result for a potential health gain." The evolution of metabolic/bariatric surgery can be viewed from several perspectives: (1) realization that bariatric surgery has always been and will always be metabolic surgery; (2) lessons to be learned from the six dominant procedures; (3) overview of the other operations that have been proposed; (4) discussion of mechanisms of action; (5) physiology of energy metabolism; and (6) introduction to the emerging concept of inflammation. This review will end with thoughts on the present and future outcomes from the knowledge we have gained from metabolic/bariatric surgery. The author concludes with the statement: Metabolic surgery is cognitive surgery.