Many actors have been known to change their entire body for a movie role – we're looking at you, Renee Zellweger and Matthew McConaughey – but this has to be the most extreme transformation we've seen yet.
Chris is the main star in Ron Howard's upcoming film In the Heart of the Sea, based on a true story that inspired Herman Melville's classic, Moby Dick.
The 32-year-old plays a sailor who gets shipwrecked for almost three months after a whale hits his ship… and as you can see Chris had to change his body for the role, a lot.
On Saturday the actor shared a photo on Instagram of what he looked like when he was filming the movie.
"Just tried a new diet/training program called 'Lost At Sea'," Chris said, joking about his weight loss. "Wouldn't recommend it."
Don't ever say Chris doesn't commit to his roles!