I wouldn't have voted for him, but where is Tom Hanks for Cast Away?
The film was shot in two parts. After his "fat half", he took an entire year off to change his physical appearance. He started on a very strict diet - fish, vegetables, very little carbohydrates, only water, etc. He would also do all types of cardio for about 2 hours a day, 6 days a week. Another thing, he actually developed an infection from a sore on his knee during the first part of the shoot, and had to undergo emergency surgery. The Doc told him that if truly had been alone on a deserted island - he would have died in 5 weeks. I guess the movie left that part out of it.