Natalie Portman may be generating Oscar buzz for her portrayal of a prima ballerina in the anticipated psychological thriller, Black Swan, but all that acclaim comes at a price.

The 29-year-old actress opened up about the physical sacrifices she had to make for the role at Tuesday night's premiere of the movie at The Ziegfeld Theater in New York. "It was an amazing experience, but definitely a difficult one," she told People of her intense dance training that lasted the better part of a year. She was determined to stay true to the role, however: "Working five to eight hours a day for a year . . . it's what real dancers live through," she said.

Portman also had to drastically alter her diet to play the wispy ballerina, and the 5'3" actress dropped 20 pounds to keep in tip-top shape during filming. "It wasn't really giving up [food]," she said. "It was just smaller portions . . . It was more quantity than a particular thing." For Portman, however, it's all a means to an end. As soon as shooting ended, so did the dieting. "It was just pasta and bread and pizza all the time," she said. "I was like, 'Please don't let there be re-shoots for this [film] because I don't think I could get back into the costumes!'"

The physical rigor of the role isn't all that's attracting attention for Portman. Black Swan also features a pretty racy lesbian love scene between Portman and co-star Mila Kunis, who had her own culinary indulgence after filming wrapped. Kunis' meal of choice? "Panda Express at JFK. I'm a classy broad," the 27-year-old told MTV.

Black Swan opens in theaters Friday, December 3. –KIMBERLY STEELE

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