"We have to shoot the really skinny stuff where we drop down to 5, 6, 700 calories a day, [for] a good three or four weeks, and it's going to be pretty uncomfortable, but we'll be together in our misery," Hemsworth told Entertainment Tonight of the extreme body prep he endured with his costars Cillian Murphy, Ben Whishaw and Paul Anderson. "I spend more time thinking about food than anything else at the moment."
The film, directed by Ron Howard, chronicles the aftermath of the real-life nautical disaster that inspired Herman Melville's Moby Dick. Hemsworth plays Owen Chase, a man who is shipwrecked with his crewmates after a whale attacks their ship in the winter of 1820.
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While Hemsworth ate "nonstop" to gain 20 lbs. of muscle for his role in Thor, the starvation depicted in In the Heart of the Sea has required the actor to essentially starve himself in order to convincingly portray a ship-wrecked person.
So what's in store for his post-production binge fest?
"All the bad stuff – pizza, hamburgers, ice cream, anything that is not on the menu – is something you have an obsession with!"