Mechanisms of Action of Bariatric Surgery on Body Weight Regulation

The anatomic manipulations during the most frequently used bariatric procedures treat the disease of obesity through a complex interplay of factors, including hormonal and bile responses, alterations in gut microbiota, and changes in energy expenditure. A new homeostatic body weight can only be achieved by an initial reduction in appetite. When the new homeostatic weight is achieved then appetite and energy expenditure return but remain in balance to maintain the new adipose tissue mass. Altered signaling from the gut to the brain, the major organ contributing to the disease of obesity, facilitates the treatment of the disease of obesity. Unraveling of the elusive physiology of the gut after bariatric surgery will not only help optimize surgical procedures, develop nonsurgical therapies, address weight regain after surgery, but will also aid the understanding of the pathophysiology of the disease of obesity itself.