Prednisone sucks and I will not go back on it ever! Besides the fact that it doesn't actually work form me, it made me gain 35lbs over 9 months. Unlike Crabby, it took me close to two years before I was final back to my pre-Prednisone weight. I am an avid power walker and did this activity the entire time I was on the Prednisone, but it didn't help. I don't want to scare you, I am just letting you know how it affected me. Hopefully you will have the same experience as Crabby and the weight will just melt off. As far as doing sit ups, I have to agree that sit ups and Crohns don't mix. Besides, you can't spot reduce so doing sit ups to lose weight on your tummy probably won't be as effective as walking or jogging three or four times per week. Get your heart rate up and you should see your weight go down or at the very least, you won't gain more. Good luck - I know how difficult it is!