Working out eight hours at a time. Swimming a mile a day. Dancing despite bruised feet, aching muscles, and a displaced rib. Natalie Portman didn't take the easy road in preparing to play ambitious ballerina Nina Sayers in Black Swan (rated R, out Dec. 3). But the 29-year-old actress says there was no other option. ''So many of the emotional scenes happen while she's dancing that there was no real way of getting around it,'' explains Portman, whose character suffers a mind-bending nervous breakdown while rehearsing to dance the lead in a glitzy production of Swan Lake. ''I do have a double for the complicated turning stuff,'' she admits. ''But anything I could do myself saved the budget hundreds of thousands of dollars in special effects.''
Logistics aside, the movie also gave Portman a chance to rekindle her childhood love of dance, which she studied from age 4 to 12. Starting a full year before the shoot, Portman and director Darren Aronofsky began assembling a coaching team that she calls the ''best of the best,'' including former New York City Ballet company member Mary Helen Bowers and choreographer Benjamin Millepied. (Portman and Millepied, 33, started dating during the shoot, but the actress keeps her personal life strictly off the record.) ''Natalie has this unbelievable work ethic,'' recalls Bowers, 31. ''She really lived the life of a dancer for the months leading up to the film.'' That meant grueling workouts six days a week and not much else even while Portman was in Ireland with James Franco and Danny McBride shooting the upcoming fantasy comedy Your Highness. ''[They] were out having fun every night, and I was the little good girl: no drinking, waking up at five to do my workouts, and not eating,'' she laughs. ''I was the really unfun one.''
In fact, Portman says that not eating or, rather, eating very little is an essential part of a dancer's lifestyle. ''I'm a very short person, and you're supposed to look very long,'' she explains. ''And you look longer when you don't have the bulk on you which is, like, sick. The whole thing, I'm aware that it's sick.''
For the record, not all of Portman got smaller while training. ''Dancers, even when they're really frailly skinny, have a very strong butt. So Mary Helen did a lot of work on my butt,'' she giggles. The result? ''Definitely a huge, huge, um...change.''