Shia LaBeouf found it "horrible" gaining 40lbs for his role in 'Lawless'
The actor put on weight very quickly for his role in the gangster film so he would be more believable as Tom Hardy's brother, but said the process was horrible as he had to wake up in the night just to drink protein shakes.
Speaking on 'The Tonight Show with Jay Leno', he said: "Once Tom Hardy got cast, he's a big boy and it became, 'Are we from the same fabric of man, can I be your brother?' Standing next to him I felt like [singer] Josh Groban, I just felt very meek.
"I gained about 40lbs, just eating, your whole lifestyle becomes something else. Every three hours you consume, food becomes vitamins, it's about necessity, which is gorging, it's horrible."
"It was protein shakes really, a lot of chicken and eggs. At night, you wake up every three hours, take the shake and wake up. It's monotonous. You only have a certain amount of time, I had a month, two months to get there."
Shia said bulking up his physique didn't make him more attractive to his girlfriend Karolyn Pho.
He added: "I was sweating like a beast snoring, it was a disaster you know, terrible."
The 26-year-old actor has also taken on another risky role recently, appearing full frontal nude in the video for band Sigur Ros' song 'Fjögur Pianó, which he said felt natural when it came to shooting the scenes.
He explained: "They explained the idea, and we get to the markers and they were like 'OK, you guys have been having sex all night, now you wake up and you stand by the wall.' And my actress showed up and she was naked, and I figured, 'Well, if we'd been having sex all night, I wouldn't have my clothes on, you don't have sex with your clothes, on,' so I thought logically I should take my clothes off."