Natalie Portman reveals drastic weight loss due to new movie role

To prepare for her role in the new psychological thriller, the 29-year-old Star Wars star underwent intensive ballet training and swimming lessons, which resulted in the tiny 5ft 3in actress losing a shocking 20lbs.

Speaking at IFP's 20th Annual Gotham Independent Film Awards in New York City yesterday, she told UsMagazine.com: 'I think it was just the physicality of it all that was the most extreme.

'I mean, I had never [done] that much training – to be doing five to eight hours a day of it was really a challenge.'

Portman added that although preparing for the role required a lot of discipline, she was happy to throw herself into the part.

She said: 'I think the most important thing is coming to work as prepared as you can be every day and working as hard as you can every day. If you do that, you can always ensure that you have an amazing experience.”

And despite all the physical hard work, the Garden State star said she would do it all again.

She said: 'I think I would do this kind of training again because it's just so rewarding. It's always one of those things where, when you put in a lot, you get out a lot.'