Bariatric Surgery Versus Diet Alone in the Bile Acid Pathway and Weight Loss

Participants will be placed into two groups. The Roux-En-Y Gastric Bypass (RYGB) group will consist of participants who will have elected to have RYGB at the Mayo Clinic Bariatric Center of Excellence. The Diet group will have a low-calorie diet prescribed by a registered dietitian. Both groups will collect stool from every bowel movement 2 days before presenting for baseline testing. Both group participants will present for baseline testing after an overnight fast and before intervention (RYGB or low calorie diet). Participants will consume a standard breakfast provided by study staff and blood samples will be collected at -15, 0, 15, 30,45,60,90,120,150,180,210,240,300,360 minutes. Appetite and satiation ratings will be recorded via questionnaires during that day every 15 minutes for the first 90 minutes, then every 30 minutes. Participants will repeat this regimen again after losing 7% of their body weight after having RYGB or low calorie diet.