The 39-year-old Swedish actor hopes he doesn't have to do the same for a sequel, reported Femalefirst.
"It was the misery diet. It was awful. I was on a strict diet and exercise plan for eight months to get in shape. I ate a lot of chicken breasts, it was really hard.
"I got called back to do more filming a few months after wrapping up and I was like, 'Nooooo' because I didn't want to go back on the diet again," Skarsgard said.