American Society for Metabolic and Bariatric Surgery review on fasting for religious purposes after surgery

      This review article is issued by the American Society for Metabolic and Bariatric Surgery (ASMBS) in response to numerous inquiries made to ASMBS by patients, physicians, ASMBS members, hospitals, health insurance payors, the media, and others regarding the safety and recommendations for fasting for religious purposes after undergoing metabolic and bariatric surgery. In this article, a summary of published, peer-reviewed scientific evidence spanning the years from 2000 to 2020 and a recently published 2021 Delphi Consensus and expert opinion is presented. The intent of issuing such a review is to provide available objective information about this topic. Unfortunately, there is a lack of published research on the effects of religious fasting on metabolic and bariatric surgery (MBS); therefore, the majority of the reviewed literature covers the effects of religious fasting on adults who have not undergone MBS. For the purpose of this review, guidance is given for religious fasting for spiritual, health, and safety benefits after bariatric surgery but not for using fasting as a weight loss strategy in the adult population. In addition, because of the absence of research on adolescents and children undergoing MBS and fasting, this review focuses on summarizing literature regarding adults and making recommendations for adults who underwent MBS and desire to fast. This review is not intended as and should not be construed as stating or establishing a local, regional, or national standard of care. This review article will be revised in the future as additional evidence becomes available.


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