Typically people who have surgery for Crohn's or UC will lose some initial weight due to the surgery itself but will find that once they are healthy that losing weight is as hard as it is for a normal person. Just because we lack a colon and have a speedier transit system does not mean that we will be skinny. Calorie abosrption takes place in the terminal ileum which remains. However, I assume that your prediabetic condition will disappear once off steroids giving you a wider range of foods to eat. I went into surgery a bit underweight (I was one of the few who lost weight on prednisone) and after surgery put on weight. I kept on putting on weight until I had an additional 30lbs on my frame and then I got serious about getting healthy. The only way to lose weight is to reduce your calorie intake and increase exercise. I did that and have managed to drop about 20lbs. I have another 10lbs to go but if I don't lose it I am happy at this weight. I do intensive cardio exercise 6-7 days per week which helps me maintain this weight and also allows me to indulge on chocolate on ocassion.