For years, Christian Bale has been sacrificing his metabolism for the greater moviemaking good. To play an emaciated insomniac in 2004’s The Machinist, the actor dropped a reported 60 pounds, only to regain the weight—and build Bruce Wayne-appropriate muscle mass—in the six months before filming his first scenes for Batman Begins. He has yo-yoed between American Psycho lean and American Hustle paunch. But even given that history, Bale’s forthcoming portrayal of U.S. Vice President Dick Cheney may be the actor’s most haunting transformation yet.

Bale might not seem like the obvious casting choice for Cheney. He’s 44, English, and, well, Christian Bale. Cheney, meanwhile, is 77, American, and his silhouette is more Penguin than Batman. But Oscar-winning filmmaker Adam McKay knew after directing Bale in The Big Short that he would be perfect to play the former veep in Vice, a comedic biopic that follows Cheney at two distinct points in his career.

“What Christian Bale really does is he psychologically breaks someone apart and puts them back together again,” McKay told Deadline. “I’ve never seen someone work so hard at it, and it is hard on him, but really amazing to watch. The second I thought of doing the movie, I knew right away, the most exciting person to play him is Christian.”

Vice, which opens in theaters this Christmas, tracks Cheney’s under-the-radar rise from bureaucratic Washington insider to the most powerful man in the world as vice president to George W. Bush, reshaping the country and the globe in ways that still reverberate today. The film reunites Bale with Amy Adams, his co-star in The Fighter and American Hustle, who plays Lynne Cheney, and features several other A-listers as Bush-era heavy hitters, including Steve Carell as Donald Rumsfeld; Sam Rockwell as Bush; Bill Pullman as Nelson Rockefeller; and Tyler Perry as Colin Powell.

To shape-shift accordingly, Bale has said that he shaved his head, bleached his eyebrows, and gained 40 pounds. (Co-star Carell also said that Bale did specific exercises to thicken his neck.) This January, Bale waved off any praise for the extreme character-preparation, telling Yahoo that he was just trying to provide “a blank canvas through which these incredible [hair and makeup] artists could create the various ages of Cheney. . . . They would shave my head every day, bleach and pluck eyebrows.”