Flickr/CC
Flickr/CC

'Avengers' star Chris Hemsworth lost around 20 pounds for his upcoming movie Heart of the Sea directed by Ron Howard, and said that the crew almost "went insane" trying to diet to look like starved shipwrecked men.

The movie releases on December 11, 2015, and is based on the non-fiction book of the same name written by Nathaniel Philbrick, about the loss of ship Essex when it was attacked by a whale in the Pacific Ocean in 1820.

Hemsworth has the lead role of the vessel's veteran first mate Owen Chase, for which he had to slim down for a lean and starving look for the shipwrecked scenes. He had already lost a lot of weight for Michael Mann's Black Hat, which was shot immediately before the historical seafaring epic.

The actor said reducing his diet drastically was a sheer "misery".

"We kind of went insane, weighing ourselves every day," Hemsworth told Entertainment Weekly. "We all felt like a bunch of supermodels, trying to get down in weight for a show, or something. That's all we spoke about. You've got 15 burly blokes on the sea and all we talked about was our diet, and who'd lost more weight, and who's looking really skinny. It's ridiculous!"

As the crew of the movie started to camp on the open seas around the Canary Islands, after shooting in London's Leavesden studios, the actors ate just 500 calories a day.

"We have to shoot the really skinny stuff where we drop down to 5, 6, 700 calories a day, a good three or four weeks and it's going to be pretty uncomfortable, but we'll be together in our misery," said Hemsworth.

In the past, he has also worked in opposite direction to get the best look for the movies such as Thor: The Dark World and Avengers: The Age of Ultron.

For Avengers, for instance, the 31-year-old actor had a routine of eating eight meals and attending gym twice a day to get a heavily built-up mass for his character.

"It's the accordion effect which is the worst part. First I had to gain 20 pounds of muscle mass for Thor and then I had to lose all that and then lose another 20 pounds to play my character In the Heart of the Sea," he reportedly told the British edition of OK! magazine.

The actor said he found himself constantly thinking about high-calorie food during his period of stringent diet.

"All the bad stuff pizza, hamburgers, chocolate, ice cream... Anything that is not on the menu it automatically is something that you have an absolute obsession with," he quipped.