Chris Hemsworth tells of how he barely ate anything to lose 15kgs to play a starving sailor in In The Heart Of The Sea...

Chris Hemworth actually caused quite a stir on social media on Sunday when he shared a shirtless selfie of himself in character for his new movie, In The Heart Of The Sea, looking gaunt after losing considerable weight for the role.

And now Chris Hemsworth is sharing how he was able to transform his Thor physique to that of a starving sailor.  Talking to KIIS FM's Kyle & Jackie O on Wednesday, the 32-year-old actor said that it wasn't hard to play the part as he was barely eating during filming, adding:

 'We felt as if we were going to pass out any second'.

The Australian heartthrob plays Owen Chase in the Moby Dick-inspired film.

His character is a sailor stranded at sea with the other crew for 90 days as they struggle to overpower the massive beast before the killer whale destructs their ship, killing many on-board.

Jackie was quick to address the unrecognizable, behind-the-scenes photo that Chris had shared on Twitter on Sunday evening.

'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,' she told him.

'I thought it was Saddam [Hussein] straight out of the hole,' her shock jock co-star chimed in, referencing the late former President of Iraq who was found hiding in an underground bunker. 

Chris, who shot to A-list fame thanks to his recurring role in Thor, explained that he'd lost about 15kgs for the part.

'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,' Chris said.

'So, what is the trick?' Jackie prompted.

'Don't eat,' Chris told her. 'Pretty straight-forward.'

In his usual self-deprecating style, Kyle joked:

 'I could lose 15kgs and still be overweight.'

Thoughtfully, Jackie asked him: 'When you're that food deprived and cranky, does it help with doing a film where you're essentially lost at sea and you wouldn't be in the best of moods?'

'It does,' Chris answered. 'Looking back, it was essential to doing the story justice. It was based on true events which inspired Moby Dick to be written.' 

He added that because of the actors' starvation before and during filming:

 'There wasn't a lot of acting required for those last couple of weeks.'

Earlier this week Chris revealed her partook in a 500-calorie a day diet ahead of his new film.

I spend more time thinking about food than anything else,' he told Entertainment Tonight.

'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,' he revealed in the interview.

The average amount of calories recommended for a man per day depends on his size and activity levels, but it's somewhere between 2000-3000.