A man dedicated to disappearing into his characters, Christian Bale is once again unrecognisable on screen. The actor talks to Susan Griffin about reuniting with the man who led him to Oscar glory.

Most people might feel a little self-conscious if they're carrying extra weight. Not Christian Bale, who spends the first five minutes of his latest film with his paunch and 'moobs' proudly on display while his character, conman Irving Rosenfeld, stands in front of the mirror tending to his comb-over.

It's quite a transformation for the actor who's played Batman on three occasions, but it's not the first time he's dramatically changed his body for a role.

Back in 2004, he became emaciated in order to portray an insomniac in The Machinist, and then lost weight again to play a drug addict in David O. Russell's The Fighter in 2010.

Bale's now reunited with the director for his waist-expanding role in American Hustle.

"I'm always interested in what David's making. I always know it's going to be really fascinating and will hopefully become very, very memorable for many years to come," says a bearded and (now) trim-looking Bale, dressed in a black button-down shirt and dark grey trousers.

Rather than sit quietly behind a monitor, when Russell directs a film, he stands just off camera, fine-tuning the acting, rewriting and feeding new lines to the actors and re-blocking scenes. It's a winning formula.

Bale, along with Melissa Leo, won an Oscar for The Fighter, while co-star Amy Adams received a nomination. Russell then led Jennifer Lawrence to Oscar glory in Silver Linings Playbook, while her fellow actors Bradley Cooper, Robert De Niro and Jacki Weaver all got nods (the first time in over 30 years that a single film had seen actors nominated in all categories).

Award success looks set to continue, with Bale, Lawrence, Adams and Cooper already recipients of Golden Globe nominations for American Hustle, a fictional take on the headline-making Seventies Abscam scandal.

Bale couldn't wait to immerse himself "in such a wonderfully, exuberant era", he reveals, and that's despite the questionable fashion. "It was like Halloween for a decade; the colours were garish. The style was just phenomenal for us to look back on, but the people themselves were no different to now," he says.

At the heart of the movie is a powerful love story between Irving and his seductive partner, Sydney Prosser (Adams), who are forced to work for a wild FBI agent, Richie DiMaso (a permed Cooper) when they're caught in a con.

DiMaso sets up a sting to capture corrupt government officials, starting with Carmine Polito, a volatile political operator played by Jeremy Renner, while Irving's unpredictable wife Rosalyn (Lawrence) proves to be the loose canon whose emotional ties could bring them all down.

As different as they might first appear, all of the characters are trying to change their lives through reinvention, explains the British actor.

"Everyone's performing in a certain way, and then at some point, it's about stripping away that mask and seeing what's really beneath," he says in a transatlantic accent, the by-product of living in LA for the last two decades.

"That's what happens, in some ways, to each one of the characters. It's an attempt to reinvent themselves, and a need to move on and find something else in their lives."

These themes were explored in Russell's two previous movies.

"David's very interested in who the true person is, what their heart is, and their soul, emotion and feeling," notes Bale, a married father-of-one.

"The characters in this are really colourful, shiny and an awful lot of fun to play. But we were shooting this film for 42 days, so you've got to find much more in order to get up and still be fascinated. You've got to go beyond colourful shininess."

The actor, who turns 40 in January, doesn't like to define what it is he loves about Irving. "Or what I really love about the film," he adds. "I do that intentionally because then you [the audience] are discovering the character, discovering the piece as you go."

Bale is known for being intense, particularly on set, as one unfortunate crew member on Terminator Salvation discovered when the actor accused him of being a distraction and launched into a foul-mouthed tirade.

But Bale makes no apologies about taking his craft very seriously.

"Everybody dreams at night. They tend to go a little insane and that's acceptable. To me, acting's like dreaming in a waking state, as you get to study people, go a little insane and be obsessive about something, and it's expected. I find that very addictive," says the actor who, aged 13, landed a starring role in Steven Spielberg's Empire Of The Sun, after the director spotted him in a TV mini-series called Anastasia: The Mystery Of Anna.

Much like the method actor Daniel Day-Lewis, his ability to 'disappear' into the character is one of Bale's hallmarks.

As Richard Suckle, one of the producers of American Hustle says: "Christian bought an amazing authenticity; it was like he stepped out of the Seventies. The way he looked, his mannerisms, the whole Bronx quality. He embodied the character as written on the page."

The movie itself defies description, veering between comedy and drama and, like all Russell films, boasts an operatic quality, which was perhaps another draw for Bale?

"The only thing I would say is I'm no fan of opera whatsoever. An operatic nature is usually something I'd laugh at," he says. "But you do get occasional moments when some sort of tragedy in your life and deep emotions can be whirled very quickly.

"Usually that would seem like melodrama, but there are times [like in this film] when it makes absolute sense. Is that a reasonable answer?"

It would take a brave person to say that it wasn't.

Extra time - Christian Bale

:: Christian Bale was born on January 30, 1974, in Pembrokeshire, Wales.

:: His father was a commercial pilot so he spent the vast majority of his childhood moving from place to place.

:: His first acting job was a cereal advert in 1983 and the following year, he starred alongside Rowan Atkinson in a West End production of The Nerd.

:: He says he's considered quitting acting twice - after starring in Empire Of The Sun and following the death of his father in 2003.

:: He married his wife Sibi in January 2000 and their daughter Emmeline was born in March 2005.

:: American Hustle is released on Wednesday, January 1