I still took the shakes and bars when I was on it and with no issue. Where as protein stuff will bother me, creatine and L-Glutamine do not. But during my first Prednisone cycle along with the creatine,and gymming it five days a week I blew up like a tick and went from 160 up to almost 210 in about two months.
I thought most of it was fat until I stopped lifting and was doing cardio to burn it off and was surprised to see I had put on a lot of muscle I had lost.