Preoperative Nutrition for Crohn's Disease Patients

The investigator hypothesizes that compliance to Exclusive enteral nutrition (EEN) will be high among patients on an operation for their bowel disease, compared to the compliance rate seen in the general Crohn\'s Disease (CD) population. Also,the investigator hypothesizes that clinical outcomes would improve, and post-operative complication rate will be reduces in malnourished CD patients receiving pre-operative 4 weeks EEN during the 4 weeks post-surgery, compared to CD patients receiving high energy and protein diet without EEN.