Some actors work harder than others for a role. Jake Gyllenhaal, you may agree, works harder than most.
Fresh from his emaciated form for 'Nightcrawler', Jake has beefed up to immense proportions for his latest role in 'Southpaw', the tale of a light heavyweight champion boxer who sees everything he cares about disappear in one terrible night, and must work to redeem himself and gain back the trust of those around him.
Watch Jake get in shape in our exhausting Featurette above, which goes behind the scenes of 'Southpaw'.
But never mind the narrative, here's what Jake had to do just to get in shape for the role of boxer Billy Hope.
The film also stars Rachel McAdams as Billy's wife, with 50 Cent as his fickle manager, and Forest Whitaker a down-at-heel trainer who only deals with amateurs. Antoine Fuqua, who previously steered Denzel Washington to an Oscar in 'Training Day' directs.
'Southpaw' is in UK cinemas from Friday 24 July. Here are some more stunning screen transformations...