Fat Girl (original title: À ma sœur!) is a French drama film directed by Catherine Breillat, released in 2001. The story is about two sisters, Anaïs and Elena, who are spending their summer vacation with their parents in a seaside town in the south of France. Anaïs is overweight and self-conscious, while her older sister is beautiful and confident.
As the film progresses, Elena starts a relationship with an older Italian law student, Fernando, who she meets on the beach. Anaïs is present when Elena loses her virginity to Fernando and becomes the only witness to their intimacy. The experience leaves Anaïs feeling confused and disturbed, and she struggles to understand her sister's willingness to give herself to a man who does not love her.
Despite Elena's insistence that she is in love with Fernando, he is only interested in using her for sex. Anaïs, who is more perceptive than her sister, warns her of his true intentions but is dismissed. As the summer progresses, Elena becomes increasingly infatuated with Fernando, while Anaïs looks on with growing horror at the prospect of her sister's inevitable heartbreak.
In the film's climax, Fernando makes a startling decision that leads to a tragic ending for the two sisters. The movie has been praised for its candid and unflinching portrayal of teenage sexuality and the pressures young girls face to conform to societal expectations of beauty and desirability.