Natalie Portman went through "extreme pain" to understand her character in 'Black Swan'.

The US actress had to live the "monastic" life of a ballet dancer to prepare for the film, and said putting herself through the physical hardships they have to endure helped her to into their right mindset for filming.

She explained: "The physical discipline of it really helped for the emotional side of the character because you get the sense of the monastic lifestyle of only working out, that is a ballet dancer's life.

"You don't drink, you don't go out with your friends, you don't have much food and you are constantly putting your body through extreme pain, so you get that understanding of the self-flagellation of a ballet dancer."

The aspect of training for the role which Natalie - who stars as The Swan Queen opposite Mila Kunis as The Black Swan in the film - found hardest was the strict diet she had to adhere to.

The film's director, Darren Aronofsky said: "There was really no money for the film and we had to push it back a lot of times. I actually don't mind that, but I only found out recently that Natalie would just be screaming at her manager that she had to live on carrots and almonds for another three weeks. She was the one who suffered the most from not eating."

Natalie added that as soon as the film had finished shooting she ate pasta "for breakfast, lunch and dinner" to celebrate.

'Black Swan' is released throughout Europe in January.