Enteroendocrine cells are nutrient sensors in the bowel that secrete special chemicals (called hormones) that control appetite and the movements all the gut. The investigators think that this control mechanism goes wrong in Crohn's patients and they have set off to do more research on this. Looking at the inside work of the gut has always been difficult and at times unpleasant for patients, however recent developments in magnetic resonance imaging (MRI) are allowing the investigators to study the workings of the gut in greater detail and without discomfort for the patients.