I take Thyroxine and will have to do so for the rest of my life. It is not through mis-use of meds but is a medical condition I have suffered from for a long time (and only discovered a couple of years ago). I did initialy lose a lot of muscle when I went on the t4 but I was eating very little as my metabolism was so slow I added fat very easily, now my metabolism is up to speed I am eating more than ever and my strength and size are definately coming back.