Bale had to switch gears pretty quickly after wrapping The Machinist to pack on some pounds of muscle for Batman Begins, the 2005 entry into the Christopher Nolan-helmed Dark Knight trilogy. In an interview with the BBC, Bale talked through the requirements — not just for getting a superhero physique, but building the stamina to act in the heavy Batsuit.
"I had to put on a great deal of weight, which was necessary for the character," he said. "He has no superpowers so you have to believe he's capable of this. I kind of knew I could do it. I think Chris [Nolan, director] was probably worrying far more than me. I was talking to him one time on the telephone whilst we were doing The Machinist and he'd say, 'How're you looking these days?'"
"It was frankly pathetic," Bale continued. "I was down to 121 pounds and I couldn't do a single push-up — this is maybe not the guy you want to cast as Batman. But we had enough time. It was an arduous journey to get there, but I managed to get into appropriate shape by the time we started filming."