Los Angeles, Aug 10 (IANS): Actor Matt Damon says he was always grumpy on the set of "Elysium" because he was on a strict diet to stay in shape.

The 42-year-old underwent a tough fitness regime and followed a strict diet plan to get in shape for the movie, directed by Neill Blomkamp. He admits giving up treats left him angry and unapproachable.

"I was grumpy on this set, because I was on a diet for the whole movie. I think I shut up a little bit and keep to myself," femalefirst.co.uk quoted Damon as saying.

"It's not even that it was as extreme as diets I've done before, but it's like, at my age, I want to eat everything in my path, you know what I mean? I think I've become more of a glutton. It was really hard because I love to eat and I love to drink," added Damon.

The actor, who raises four daughters Alexia, 14 , Isabella, six, Gia, four and Stella, two, with wife Luciana Barroso, had previously said that his wife doesn't mind when he changes shape for movies because she "likes the variety".

"I'm at the point in my life where somebody was silly enough to marry me and won't leave me if I put on a few pounds," said Damon.

"I think my wife likes the variety. When I did 'The Informant', I put on 40 pounds. I was like, 'You like this guy, too, don't you?' I'm trying to talk her into that guy. That's the guy I'm most comfortable being," he added.