Supes is able to use his blue suit to change the red Kryptonite to blue, causing the ill effects of becoming a skinny person to be reversed, and for Bizarro to grow weak. In "Revenge Of Bizarro", blue Kryptonite was not able to instantly cure Superman of his extra arms and legs, saying it would later wear off. But, in "Terror From The Phantom Zone", the blue was able to reverse the aging process that was put upon Supes from the red.