I don't pretend to know a lot about medications. I was doing some research recently for a friend that is on Prednisone and learned that when taking a medication that has steriods in it for a long period of time the patient can actually gain up to 35 lbs. and it's almost impossible to lose.
The best advice I can give for losing weight is eating a healthy diet and getting outdoors and walking as much as time allows. Skipping meals and starving yourself is not the answer. The best kind of food to eat is what you prepare yourself, there is nothing like a home cooked meal.