Although it is true that pred does change your metabolism and that some people gain a lot of weight I gained 0 lbs after being on 60mg for many months. I have been on pred for 5 years now and weigh the same as I did at 16 ( I am 67 now). Too many patients continue to eat normally when they are ill, have lost muscle mass, and are much less active than before getting sick. In addition many actually eat more due to the tremendous stress of their disease. I am not saying this as criticism but clinically what might be happening.
Adjust your eating habits. Eat less calories. Reduce carbs, particularly simple carbs. Exercise as much as you can. Don't just accept the canard that you will gain massive amounts of weight on pred....not true.
MCTD (lupus, scleroderma, polymyositis). Diagnosed 2005. Kidney, liver, GI tract, dysphagia, raynauds, Barretts esophagus, quadriplegic in 2005. Recovered and now active in skiing, tai, chi, hiking, golf. Meds: prednisone 2.5mg, imuran 25mg, amlodipine, benazapril, omeprazole, potassium, folic acid, vitamins, maxide and various supplements and vitamins.
Remain optimistic and you can overcome the odds.