In an interview with W Magazine for the cover of its Best Performances issue, Joaquin Phoenix was asked about his diet when working on Joker.

It was clear just from watching the movie that Phoenix must have undergone a severely restrictive diet and now, that is confirmed.

“Well, I was living like a hermit because I was on an extreme diet,” Phoenix told the publication. “You can’t really socialize when you’re not eating or drinking.”

As for if the diet and the role affected his dreams, Phoenix responded, “Yes. I was always dreaming about food. I’d dream that I ate a huge meal. And I’d wake up feeling so guilty.”

Phoenix was also asked whether he had dance training for the movie. He famously dances down a large set of steps in the Bronx towards the climax of the film: “Yes. And I worked with a choreographer for Joker. Normally, I don’t like talking about character with anyone other than the director, but the choreographer gave me a vocabulary that informed the role. I wanted to go from joy and euphoria to something painful. Dance gave me that language. And hunger.”

For more interviews with the best performers of the year, head to W Magazine.