After providing informed consent the volunteers will be screened for inclusion/exclusion criteria. Participants fulfilling the inclusion/exclusion criteria will undergo baseline symptom evaluation, endoscopy, an upper GI series and esophageal function testing using combined MII-EM as part of the pre-operative work-up. The same examinations (symptom evaluation, endoscopy, upper GI series and esophageal function testing) will be repeated 3 months after successful conversion from gastric band to bypass.