Anais Reboux was only 13 years old when director Catherine Breillat spotted her at a McDonald's. Breillat became interested in Reboux even though she had no previous acting experience. Breillat had Reboux do a screen test. The first screen test went wrong but Breillat insisted on doing another because it turned out that the original casting director didn't know how to handle Reboux. In the end Breillat had Reboux re-tested along with another girl and had them read from Rohmer's Pauline à la Plage. The two of them started to talk and that's when Breillat realized that Reboux wasn't just reading it, she was feeling it, and having a real conversation thus leading her to get the role of the main character in 'Fat Girl'.
