Patient eligibility criteria: between 19-70 years of age at enrollment, BMI ≥ 40 kg/m2, and the subject is under consideration for surgery for obesity or metabolic disease and elects to undergo a primary loop duodenal switch procedure or as a conversion procedure for failed, sustained weight loss after a sleeve gastrectomy or laparoscopic adjustable gastric band performed more than 12 months prior to time of evaluation. All subjects will undergo a standard comprehensive bariatric surgery evaluation which includes but is not limited to nutrition consultation, psychological evaluation, laboratory tests and supervised medical weight loss. Once the study subjects have met all of the insurance requirements, the bariatric clinic will submit for insurance approval for a duodenal switch operation. Once surgery is approved, study subjects will have a standard pre-operative history and physical visit no more than 30 days prior to surgery and will fill out a survey regarding health-related quality of life and amount of gastrointestinal symptoms experienced (diarrhea, constipation, bloating, etc).