Why Does Gastric Bypass Surgery Work?

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Science  26 Jul 2013:
Vol. 341, Issue 6144, pp. 351-352
DOI: 10.1126/science.1242673

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Bariatric surgery to alter the digestive tract is currently the only effective treatment option with sustained beneficial effects on body weight and comorbidities such as type-2 diabetes (1, 2). Identifying the mechanisms that underlie these remarkable outcomes could help guide the development of “knifeless” approaches that may one day replace quite invasive surgeries (which often result in serious complications). Changes in circulating gut hormones induced by bariatric interventions could affect signaling to the brain and other organs, changing energy intake and expenditure, as well as glucose production and disposal (3, 4). On page 406 of this issue, Saeidi et al. (5) propose another possibility—that the rearranged gut itself improves glucose homeostasis. This may explain why gastric bypass surgery patients can stop taking diabetes medications before substantial weight loss has occurred. This radically new view of bariatric surgery is therefore not based on how the changed gut “talks” to the rest of the body by humoral and neural signaling, but rather on metabolic consequences of the surgery within the gut itself.