Jake Gyllenhaal would get fat for an acting role.

The 34-year-old actor spent months in physical training and on a strict diet in order to get fit for his part as champion boxer Billy 'The Great' Hope in forthcoming movie 'Southpaw', but he has revealed that he would happily pile on the pounds for a part.

Asked whether he would ''get fat'' for a role, Jake said: ''Absolutely!

''I mean I think, it just depends on the role and it depends on if I'm driven by it. I like to learn and do almost anything for a role. It's not an easy thing that, but I'd give it a go.''

Despite being one of Hollywood's most sought-after stars, Jake - who will also appear as a mountaineer in forthcoming 3D film 'Everest' - admitted that he is not always a fan of watching himself on screen.

He told BBC Radio 1: ''It is strange to watch yourself but I love movies and I love making them and the stories are really interesting to me.

''Shaping them you know, when you're watching them be shaped by an editor and they're becoming a movie after you've shot many different scenes, that's amazing to see.''

Meanwhile, Jake revealed how he was mentored by a cop to prepare for his 2012 film 'End of Watch' and they subsequently became friends.

He said: ''I learned everything about being a police officer and everything involved in it. All the lessons he learned and everything he had been through, and we became close.''