The Impossible star joined Chris Hemsworth and Cillian Murphy in the cast of In the Heart of the Sea playing emaciated whalehunters who are stranded after a shipwreck.

Chris has been vocal about the tough task of slimming down, admitting he lived off "a boiled egg, a couple of crackers and a celery stick" during the gruelling shoot, but his co-star Tom was not allowed to lose any weight for the role because he was under the age of 18.

The actor, now 19, reveals he tried to bend the rules by piling on the pounds before filming started so he could be shown getting thinner throughout the movie.

Tom tells Britain's Independent newspaper, "When we first started getting into shape I was notified that legally I wasn't allowed to lose any weight I had previously so I had to gain as much weight as I could prior to the weight loss and then lose it all again. Towards the end of the film I did lose a little more than I should have but it's my art and I love it."

After the shoot, Tom then had to bulk up to play superhero Spider-Man in Captain America: Civil War, which is due for release next year (16).