METHODS: A committee of 61 well-known metabolic and bariatric surgeons from 24 countries was created to participate in the Delphi consensus. The committee voted on 45 statements regarding recommendations and controversies around fasting after MBS. An agreement/disagreement ≥ of 70.0% was regarded as consensus.

RESULTS: The experts reached a consensus on 40 out of 45 statements after two rounds of voting. One hundred percent of the experts believed that fasting needs special nutritional support in patients who underwent MBS. The decision regarding fasting must be coordinated among the surgeon, the nutritionist and the patient. At any time after MBS, 96.7% advised stopping fasting in the presence of persistent symptoms of intolerance. Seventy percent of the experts recommended delaying fasting after MBS for 6 to 12 months after combined and malabsorptive procedures according to the patient's situation and surgeon's experience, and 90.1% felt that proton pump inhibitors should be continued in patients who start fasting less than 6 months after MBS. There was consensus that fasting may help in weight loss, improvement/remission of non-alcoholic fatty liver disease, dyslipidemia, hypertension and type 2 diabetes mellitus among 88.5%, 90.2%, 88.5%, 85.2% and 85.2% of experts, respectively.