I love going to Internet Movie Data Base:
http://www.imdb.com/name/nm0001319/bio
http://www.imdb.com/title/tt0364845/ (for the whole cast)
If you look at McGee's (Sean Murray bio) you will see that his step-father is in charge of the show so I doubt that he would be leaving it. He lost all that weight by dieting - eating all organic. I hope he does not loose any more.