01/12/2014 07:45 GMT | Updated 01/12/2014 08:59 GMT

Jake Gyllenhaal Is Unrecognisable After Beefing Up To Play A Boxer In ‘Southpaw' (PICS)

The last time we laid eyes on Jake Gyllenhaal, he was looking a lot skinnier than his usual defined self after losing 30lbs to play a sociopath in the crime thriller ‘Nightcrawler’, which makes his latest transformation all the more astonishing.

The actor has now gone to the other end of the weight spectrum after massively bulking up to play a boxer in the forthcoming ‘Southpaw’.

Jake Gyllenhaal (yes, really)

The 33-year-old star gained 15lbs of muscle to look the part for the role, which involved working out for six hours a day for six months.

Talking to Deadline Hollywood about Jake’s transformation, ‘Southpaw’ director, Antoine Fuqua said: “We literally turned him into a beast. Jake, my god, he’s a very electric, powerful fighter in this movie. He’s so committed and gives his heart. The word is sacrifice.”

Jake was looking noticeably slimmer for his role in 'Nightcrawler'

It’s not uncommon for actors to radically transform themselves for the sake of a role.

Matthew McConaughey survived on Diet Coke, egg whites and a piece of chicken a day to lose 40lbs for his Oscar-winning turn in ‘Dallas Buyers Club’ last year.

Whilst Renée Zellweger famously gained 30lbs to play Bridget Jones in 2001 after feasting on 4000 calories a day.

See which other Hollywood stars have undergone body transformations for film roles in our gallery below..

Photo gallery Actor Transformations See Gallery