Hugh Jackman said that for his shirtless scenes in this movie, he wanted to look "as ripped and cut as possible." So he adopted a dehydration diet (used in bodybuilding) where he did not consume any liquid for thirty-six hours before filming his shirtless shots. He said it made him feel "headachy" and faint, but he was pleased with the results, as dehydrating tightened everything up, and gave him the exaggerated muscle definition and vascularity that he wanted to show in his shirtless scenes.
To prepare for the role, Hugh Jackman contacted Dwayne "The Rock" Johnson for advice on bulking up for the movie. Johnson suggested Jackman could gain a pound a week over six months (twenty-four weeks) by eating six thousand calories a day of "an awful lot of chicken, steak, and brown rice."
Hugh Jackman said that with this movie, he finally achieved the physique that he always envisioned in his mind that Wolverine should have. He said that for some reason, on each of his five prior takes at the character, he felt that he never had enough time to get in shape. For this movie, he finally had enough time, and got his body exactly the way he wanted it to look. Will Yun Lee also said that it was Jackman's best physique for the role of Wolverine.
Hugh Jackman is a self-confessed fan of the Chris Claremont-Frank Miller "Wolverine" comic (1982), especially the Japanese saga: "There are so many areas of that Japanese story. I love the idea of this kind of anarchic character, the outsider, being in this world full of honor and tradition and customs; someone who's really anti-all of that, and trying to negotiate his own way. The idea of the samurai too, and the tradition there, it's really great. In the comic book, he gets his ass kicked by a couple of samurai, not even mutants."
Guillermo del Toro expressed interest in directing, being a fan of the Japanese saga in the "Wolverine" comics. He met with James Gianopulos and Hugh Jackman about directing, but ultimately decided he did not wish to spend two to three years of his life working on the movie.