Actor Chris Hemsworth lose 15 kgs off his weight during the production of his new film.

The “Avengers: Age of Ultron” star is not sick but he trimmed tons of weight just so he could convincingly portray a role of a starving sailor in the movie “In The Heart of the Sea.”

The movie is based on real life events. Hemsworth played a 19th-century sailor, first mate Owen Chase, who served on the whaling ship, Essex, but ended up stranded at sea for 90 days after a whale destroyed their ship, Inquisitr noted.

When their ship was destroyed, Chase, ship’s captain George Pollard, Jr. (Benjamin Walker), and the rest of the crew have to survive the elements and the lack of food in a lifeboat-sized craft.

The cast members’ had to go on a diet to steadily reduce weight over the course of the production to realistically depict starving ship crew, Entertainment Weekly reported.

Hemsworth shared on Twitter a photo of himself, in which he looked totally different when he played the character Thor.

Director Ron Howard told EW that the entire cast had to work out every single day, even when they were filming. He said that although the cast lose weight rapidly, it was done in a healthy way.

The Australia actor and the rest of the cast were only consuming 500 calories a day when they were filming in open sea around the Canary Islands, EW added.

“When you’re already starting off lean, its brutal to chew through that kind of weight. Every pound feels like a kilogram,” Hemsworth told EW.

The 2014 People “Sexiest Man Alive” also revealed to KIIS FM’s Kyle & Jackie that “Castaway” actor Tom Hanks also gave them some advice on how to shed some weight.

“I saw this photo of you the other day that you’d posted up – you looked like, it’s like the Tom Hanks, Castaway sort of physique,” Jackie told Chris.

“It’s funny you mention ‘Cast Away’ because we called up Tom Hanks and he gave us some advice on how to lose the weight,” the actor replied.

“So, what is the trick?” Jackie asked.  “Don’t eat. Pretty straight-forward,” said Hemsworth.

Inquisitr noted that before Hemsworth started filming “In The Heart of the Sea,” he had already trimmed down when he starred in Michael Mann’s thriller “Black Hat.”

“In The Heart of the Sea” will hit theaters on December 11.