Background: Roux-en-Y gastric bypass (RYGB) is the most common bariatric procedure worldwide. There are few studies investigating how early return to solid food affects complications. Objective: The aim of this study was to explore how oral intake was resumed in RYGB patients and how the postoperative food regimen affects outcomes, such as complications and length of stay. Setting: Retrospective nationwide registry study. Methods: The Scandinavian Obesity Surgery Registry included prospective data from RYGB patients operated in 2009 to 2014. A questionnaire assessed the postoperative reintroduction of solid food applied at each bariatric center. The postoperative regimen was established in 23,589 patients. Outcomes were recorded at 30-day follow-up according to the standard Scandinavian Obesity Surgery Registry routine. Results: Nine percent of patients (n = 2074) returned to solid food within the first week after surgery. Most commonly solid food was resumed in week 4 (37%, n=8659). Median length of stay was 2 days for all. Of all, 2.8% suffered from a severe complication (amp;gt;Clavien-Dindo 3a). After adjusting for the annual volume of procedures at hospitals, there was no correlation that the timing of solid food affected complication rates. The odds ratio for a severe complication was significantly lower for intermediate- (odds ratio .64 95% confidence interval .48.85) or high (odds ratio .52 95% confidence interval .42.66) volume centers. The rate of leaks and small bowel obstructions were evenly distributed between the different postoperative food regimens. Conclusion: Early return to solid food after RYGB did not affect the risk of severe complications. Patients operated at centers with an annual volume of amp;gt; 100 procedures have a lower risk of severe complications. (C) 2018 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.