Mila Kunis was happy to go back to her normal body size after working on 'Black Swan'.

The actress - who stars opposite Natalie Portman in the Darren Aronofsky - directed psychological thriller about a troubled ballet dancer - had to lose weight to become a typical dancer in the film, but was grateful to stop working out when it had wrapped.

She said: "To be able to pretend to be a ballerina for five months was great - but boy, was I happy to get out of that life."

However the Hollywood beauty did enjoy the "challenge" of becoming so physically fit.

She said: "The best part was the challenge of it, the challenge of changing your body."

Natalie - who won the Best Actress Oscar for the role earlier this year - worked out for eight hours a day to get as thin as she could to play a dancer.

Discussing it recently, she said: "You are constantly putting your body through extreme pain, so you get that understanding of the self-flagellation of a ballet dancer."