In preparation for their roles in 'Joker: Folie à Deux', Joaquin Phoenix and Lady Gaga underwent significant physical transformations, with Phoenix praising Gaga for her impressive weight loss during rehearsals. Gaga, who plays Harley Quinn, shared her approach to embodying her character, focusing on emotional depth rather than her usual vocal techniques. Phoenix, who previously lost 52 pounds for the first 'Joker' film, noted that this time the weight loss was more complicated due to the dance elements involved. Both actors expressed concerns about the obsession with weight loss in their preparation, with Phoenix vowing to avoid such extreme measures as he ages. Gaga's past struggles with eating disorders added a layer of complexity to Phoenix's comments about her transformation, raising questions about the impact of such remarks on mental health. The film, directed by Todd Phillips, is a blend of thriller and musical elements and premiered at the Venice Film Festival.