For her role in "Black Swan," Natalie Portman lost about 20 pounds, bringing her weight down to around 95 pounds. This drastic weight loss was part of her preparation to portray the physically demanding role of a ballerina. Portman's transformation earned her critical acclaim, and she won the Academy Award for Best Actress for her performance. However, the extreme weight loss raised discussions about the pressures on actors and the impact on health and body image in the film industry.

"Black Swan: Metamorphosis" explores themes of ambition, duality, and the psychological toll of perfectionism. The film follows Nina, a ballet dancer who becomes consumed by her desire to embody both the innocent White Swan and the seductive Black Swan in Tchaikovsky's "Swan Lake." As she strives for perfection, she battles internal and external pressures, leading to a descent into madness. The film illustrates the struggle between one's desires and the fear of failure, ultimately highlighting the destructive nature of obsession and the sacrifices made for art.

In "Black Swan," Mila Kunis portrayed Lily, a rival dancer to Natalie Portman's character, Nina. While Kunis trained in ballet for the role, most of the dancing scenes were performed by professional ballet dancers. The film's choreography involved a blend of the actors and body doubles to create the illusion of ballet performance. Natalie Portman, who played Nina, had extensive dance training, and her dancing scenes were primarily performed by her with the help of a body double for some sequences.

Natalie Portman has expressed that "Black Swan" was a transformative experience for her, both personally and professionally. She has highlighted the intense physical and emotional preparation required for her role as Nina Sayers, a ballet dancer striving for perfection. Portman praised the film's exploration of duality, mental health, and the pressures of performance. Winning an Academy Award for her portrayal, she emphasized how the film resonated with her on multiple levels, showcasing the dark side of ambition and artistry.