I'm on prednisone and as one of the side effects I'm always hungry....?

I was just discharged from the hospital and i've been diagnosed with moderate crohns (nearly severe, but it wasnt bad enough to be called severe, but im close). Now I'm on 40 mgs of prednisone a day and it drives me crazy, I always want to eat! But I lost so much weight from being not being allowed to eat or drink (i had to do a lot of tests that involved having clear intestines) in the hospital and I don't want to gain it all back. I realize that I'll gain a little bit but I'd like to stay as thin as possible. So what do I do when I've already eaten a good enough sized meal and I still feel like eating? Please help, I'm supposed to be taking the prednisone (medical sterroids for anyone who doesn't know) for 2 and a half months and I don't want to go back to being as fat as I was before not being allowed to eat in the hospital.