Joseph Gordon-Levitt hated preparing for his role as a porn-obsessed bodybuilder in Don Jon because of the amount of meat he had to eat to pile on the pounds.
The actor made his feature-length directorial debut with the film, in which he plays a New Jersey man addicted to X-rated films and working out.
Gordon-Levitt spent hours in the gym for the role and restricted himself to a protein-rich diet - and he admits he couldn't understand why anyone would want to live that way.
He tells Britain's Esquire magazine, "It was really good research getting into that character head space, being so into your appearance and working so hard on it (but) it's not even that healthy, bodybuilding.
"I was eating multiple pounds of meat, chicken and fish every day. That's too much meat. I don't think it's great for your heart - but it does make you big."