He lost over four stone for his role as an emaciated insomniac in The Machinist, and two to play Dicky Eklund, a real-life boxer and former drug addict, in The Fighter.
Yet, the talent – which has earned Christian Bale a slew of awards – goes far beyond a willingness to suffer extreme transformations. After starring with him in the boxing movie Mark Wahlberg said he just "inhaled" his character. "He became him".
This hard work and effort evidently paid off, as in 2011 his perfomance in The Fighter was awarded with an Oscar for Best Supporting Actor.
The youngest of four children, he was born in Wales on January, 1974 and raised in a family steeped in the entertainment business.
One grandfather was a stand-up comic, the other was a stand-in for John Wayne.
His mother Jenny was a circus performer, and his father, David, left his career as a commercial pilot to manage Christian when it became clear that there was a promising future ahead of him in film.
A brief appearance in made-for-TV drama Anastasia, when he was 12, with Amy Irving, then married to Steven Spielberg, led to his breakthrough role.
Christian beat 4,000 other hopefuls to star in the famed director's war movie Empire Of The Sun.
It was then, though, he learned to be wary of the attention that comes with being a movie star.
"Girls were all over me, boys wanted to fight me, and I was being asked to open local fêtes when all I wanted to do was ride my BMX bike in the woods," he recalled.
"I told my parents I wasn't interested in doing anything again because the attention ruined it".
He didn't stay away for long, returning in Kenneth Branagh's Henry V and a movie version of A Midsummer Night's Dream with Michelle Pfeiffer and Calista Flockheart.
In 2000, he blew US audiences away with a scarily intense portrait of a serial killer in American Psycho and then in 2005 in the title role of Christopher Nolan's Batman Begins.
Along the way Christian also earned a reputation for having an explosive temper.
Just after the second of his Batman films, The Dark Knight was released, he was arrested in London for allegedly assaulting his mother and sister.
The charges were dropped, but the incident was followed by the leaking of an unfortunate recording of the actor on the set of Teminator Salvation. Christian was seen launching a tirade at a crew member.
He apologised profusely and members of the profession, including Whoopi Goldberg, rallied to his defence.
The film's director McG explained that the incident "was taken wildly out of context".
"The truth is simply Christian’s a good guy. Don’t accuse him of being a bad guy because he’s not.
"He loves his family, he has no entourage, he’s an actor’s actor and he operates from a place of passion".
The family, to whom he is devoted, is his wife Sandra 'Sibi' Blazic, a former model, and their daughter Emmaline.
They were introduced by Winona Ryder, his co-star in Little Women, who had hired Sibi as a personal assistant.
Their marriage in 2000 showed Baleheads, as his fans are known, the actor's softer side.
Of his little girl, born in 2005, he said: "I've absolutely fallen into the cliché of a dad who could happily talk about my daughter endlessly".
When the star took home his first Academy Award for his portrayal of Dicky Eklund in The Fighter, he expressed his disbelief at the situation.
"What a room full of talented inspirational people – what the hell am I doing here?" he quipped as he picked up his gong - before paying tribute to his wife Sibi - "my mast through the storms of life".
In 2013, Christian starred in Out of the Furnace and American Hustle. He recieved a Golden Globe nod for Best Actor for American Hustle, as well as another nomination for the 2014 Oscars.