Ben Affleck enjoyed ditching his strict diet for Gone Girl.
The 42-year-old actor, who has since beefed up to play Batman in 'Batman v Superman: Dawn of Justice,' embraced the opportunity to gain weight for his role in the new drama.
He said: "I ate unhealthily, so I would look like a slob."
The Oscar-winner was also relieved to only have to focus on being in front of the camera after both directing and starring in Argo.
He said: "It was a relief. David Fincher [the director] could say 'cut,' and I could go back to my trailer and if the whole thing fell down, I'd be like, 'OK, you deal with it.' It was nice not to have that on my plate."
The 'Good Will Hunting' star credits his wife Jennifer Garner, with whom he has daughters, Violet, eight, and Seraphina, five, and son Samuel, two, for first encouraging him to take on the adaptation of Gillian Flynn's best-selling novel.
He told Us Weekly magazine: "She'd read it it and she's friends with [producer] Reese [Witherspoon]. Our kids hang out. And then there was never any question once I knew David Fincher was directing it. I would have read the phone book for him!"