I know what you're going through, I have Colitis, and have been on Predisone for it before. I also gained a ton of weight (about 30 pounds, from 110 to 140!!!). What I found helped - walk as much as you can, I know it can be hard to make yourself do it, especially when you're feeling crappy, but it will help to keep the weight off. I would try to fill up on things like low fat Jello and low salt chicken broth. And one other thing, if you haven't been through this before, use a moisturizer with Vitamin E and Aloe all over constantly, the rapid weight gain may give you stretch marks - I still have them 7 years later, even though I've lost the majority of the excess weight. Anything you would use to help to prevent stretch marks in preganancy will help.

And one other thing, when I was starting to decrease my dosage to wean off of it (you can never stop taking it suddenly) I had to be very careful what time of day I dropped my dosage. Tried to take 1 pill off the set I took right before bed, and woke up with the most horrific leg pains I've ever experienced. Learned to lower my middle of the day set instead.