The 42-year-old actor, who has been busy filming Martin Scorsese's "The Wolf of Wall Street", has undergone an extreme diet to portray an HIV/AIDS-infected man in true-story drama, reported Ace Showbiz.
"I'm playing a guy who was sick and would have loved to have been healthier but wasn't. For me, it's more of a mental thing than physical thing. I'll get down to the weight I need to get to. I'm on my way, and it's what I need to do for the job," he said.
In "Dallas Buyer's Club", the "Fool's Gold" star plays Ron Woodroof, a real life figure who was also a heterosexual man diagnosed with AIDS in 1986.
"I should not look healthy by the time I'm doing this. It's a bit of a spiritual cleanse, mental cleanse." he added.
The film is directed by Jean Marc Vallee and also stars Hilary Swank in it.