A high dose of steroids, if your body is not using them, will cause Cushing's syndrome. With that, you will get weak bones and muscles and well as weight gain and possibly other symptoms like diabetes, high cholesterol, poor healing, depression,...
The *art* with steroids is to take just what you need. Too much - and they will destroy your body.
Too little, after you have become dependent, can cause you to have an adrenal crisis - so you must change doses slowly or risk getting very sick or dying.
I had Cushing's and now have no adrenals. I live on steroids.