Natalie Portman endured a punishing schedule for her role as a ballerina in Black Swan, which left her fearing she was going to die.

The waif-like 29-year-old lost 20lb for the role, eating little more than carrots and almonds on a punishing diet, and spent eight hours a day in rehearsals. Ms. Portman, who won an Oscar for her portrayal of the desperately ambitious, perfectionist dancer, said: "There were some nights that I thought I literally was going to die."

The film left her physically and emotionally drained: "It was the first time I understood how you could get so wrapped up in a role that it could sort of take you down."

The actress, who dislocated a rib during rehearsals, said recently: "All dancers are always dancing with an extreme injury. Not just a sore muscle, they're dancing on a sprained ankle or with a twisted neck or something. You'll see them do incredible stuff and then limp off stage, straight to a bucket of ice. Part of the art is hiding all the pain."

The film received mixed reviews from ballerinas. Racheal Prince, of Ballet British Columbia, said she thought Ms. Portman's character was exaggerated. "She's anorexic, bulimic, crazy," the 26-year-old dancer said. "I'm sure every dancer struggles with little things here and there, but for one girl to struggle with every single problem out there, it just makes us look crazy."