1. Center for Morbid Obesity and Bariatric Surgery, Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway;
2. Department of Gastrointestinal Surgery, Vestre Viken Hospital Drammen, Drammen, Norway;
3. Department of Gastroenterology, Oslo University Hospital and University of Oslo, Oslo, Norway;
4. Department of Gastrointestinal Surgery, Oslo University Hospital, Oslo, Norway