 The PhD. project will consist of clinical trails on patients that will undergo gastric bypass surgery. The studies will take place before and within the 1. week after surgery. The investigators will measure different hormones and adipokines in fast and the postprandial state. To discover possible new proteins the investigators will run proteomic on some samples. All the results will be compared to the same parameter on patients undergoing gastric banding, where the anatomy of the intestine hasnt been changed. 