My husband was on prednisone also, and gained some weight.  He put himself on a fruit and salad diet.  Salad with turkey, tomatoes, and some cheese, ate lots of oranges, bananas,  and yogurt. (no apples though, system didn’t not like them :)).  He lost 20 lbs in a month, which I thought  was great and he is keeping it off with this eating habit.  At night he really watchs his portions mostly. no soda  He just came back from the doctors and the doc was impressed with his weight, but would like to see him lose a little more.  My husband has LUPUS, so has some of the same meds, along with different ones.  Weight is a big issue, because of the stress on the joints and such.