Prednisone blocks the inflammatory process, and lets your body heal on its own. It's not a "real" medicine, like an antibiotic. It does make you more susceptible to illness, because it lowers your immunity,.....because it blocks the inflammatory process.
After you have been very sick, with for example an auto-immune disease, and start taking Prednisone, withing a day or 2, you feel like you could run a marathon. You know in your heart, that you can't, but your mind says you CAN! I always have grandiose ideas, when I take it. Usually I end up in bed again because I pushed myself too hard, before my body was ready.
So, MsMcDucket, take it easy. And don't eat too much. Your body also doesn't know you have eaten, or are full. I eat, and eat, and eat!!! I would go to bed, and think about what I was going to eat for breakfast.