Tobey Maguire struggled to lose weight for his role in 'Brothers'.

The 34-year-old actor - who plays a troubled marine in the movie - had to work hard to shed the pounds, restricting what he ate and increasing his work-outs.

He said: "I had to do it quickly too! It wasn't fun to get there. I didn't eat a lot, and I worked out a lot. I cut my diet down to 1,200 calories a day, with lots of cardio. You get into a weird mindset and get so tired."

However, the 'Brokeback Mountain' star insisted his efforts were worth it as he had been wanting to work with actress Natalie Portman and director Jim Sheridan for a long time.

He added to Elle magazine: "It was challenging. Some of the conditions were tough and pretty intense. But I've been wanting to work with Natalie Portman, so I was very happy to get that opportunity. And Jim Sheridan has a really passionate spirit. He really likes to explore and investigate as he's working. So you sort of follow your nose, you go and find it."