First, ensure your physician has filed an adverse reaction form. The last time I did this 2 years ago I gained 60 lbs. For treatment of MS flares we use large doses of steroids. This is based on clinical practice, not great research. However, it seems to works better than lower doses.
Steroids generally accelerate the aging process.
That is, they cause cataracts, osteoporosis, diabetes, muscle atrophy, etc., but there is no alternative. The only thing you can prevent is to take a drug for osteoporosis while you are taking steroids - Fosamax or Miacalcin. Some prefer Vitamin D and calcium, but research seems to favor the Fosamax. There are no known ways to block the weight gain. Solumedrol or methylprednisolone is used in the treatment of various diseases.