Hey tater, did you gain weight by taking prednisone? I gained 20 pounds in 1.5 months of taking 40mg, i've been tapering the last 4 weeks, I hope the weight gain slows down. I never weighed 135lbs ever in my life and I know it's a healthy weight at 5'7 but I feel big, all the weight went to my stomach area and back. I'm glad you asked this question on how to loose it. It seems like it's going to be a pain.
Water is one solution for sure, avoid pop, coffee, sugar juices for sure!
I hate eating 6 small meals a day b/c I feel like i'm eating all the time but it does help the cravings if you still get them (I never had them til I started pred) Bananas, Apples (peeled helps if the skin bothers your stomach), and stuff like that will help.
Also I lift weights (not heavy ones, 10lbs) and do 25 reps per arm a day, not a lot but I've noticed my muscles get bigger in the arms.. lol.. I also try to walk a mile or two a day when possible (It's started to snow here, so it's not easy, I got a treadmill tho)
Best of luck to you and anyone else dealing with weight gain from pred or another way they got it! :)