Mila Kunis gained back the weight she lost for 'Black Swan' in five days.

The actress - who stars opposite Natalie Portman in the Darren Aronofsky directed psychological thriller about a troubled ballet dancer - lost 20lbs over five months to achieve the body of a typical dancer for the film, but admitted she wasted no time in gaining it back once filming ended.

She told Live magazine: "I trained four hours a day, seven days a week, for seven months. I had one day off on my birthday and half a day off for the Emmys and the Golden Globes. On those days my ballet instructor worked with me from 5am to 11am, then I went to hair and make-up and on to the awards shows. I lost 20lb. Aesthetically, I had to look like a ballerina and hold myself like one. By the end, I was 95lb. All you saw was bone. It looked disgusting, but in photographs and on film it looked amazing. It took me five months to lose the weight, but just five days to gain it all back."

Not surprisingly Mila's parents were horrified by her weight loss and she revealed they think her job is "absurd".

She explained: "My father is a mechanical engineer. My mother is a physics teacher. They have this hard-working son who's a biochemist in San Diego, trying to cure cancer and who can barely pay the rent. Then they have me - this daughter who earns an obscene amount of money for not doing anything. They think my job is absurd"