Zach Galifianakis displayed drastic weight loss at a screening of Birdman in New York

Zach Galifianakis before and after weight loss

He played the portly and lovable Alan in the 2009 comedy hit The Hangover.

But Zach Galifianakis was more Bradley Cooper than the rotund funny man fans are used to seeing when he attended a movie screening on Saturday showing-off a much slighter frame.

The 45-year-old actor displayed the drastic weight loss at the premiere of Birdman at Alice Tully Hall in New York - his first public event in a year.

Zach Galifianakis before and after weight loss

While there, the Campaign star spoke to The Hollywood Reporter and revealed his feelings about life in the spotlight. He said: 'It's confusing to me - all of this is confusing to me. They oversell it like we're curing cancer, you know what I mean? I just think it can be gross sometimes, the way Hollywood congratulates itself all the time.'

Earlier in the day at a press conference, the funny man reportedly said: 'Being a celebrity is sh*t - it's dumb, and I'm not interested in it,

'I like to be an actor, and that's it. The blurred lines are, I think, man-made. I think celebrity is a man-made thing; it's not innate in us…I'd rather just do my work and go home and watch Lifetime.'

The Due Date star looked dapper in a grey suit featuring fine blue checks and matching pale blue shirt with navy tie to complete the ensemble.

He also sported jaw-length curly locks as well as his signature scruffy beard.

According to IMDb, Birdman Or The Unexpected Virtue of Ignorance focuses on a washed-up actor called Riggan Thomson, played by Michael Keaton, 'who once played an iconic superhero'.

He 'must overcome his ego and family trouble as he mounts a Broadway play in a bid to reclaim his past glory.'

Naomi Watts plays the protagonist's girlfriend, Lesley, a nervous actress in the play while Zach plays Jake, the play's producer, in the black comedy.