Matt Damon thought George Clooney was playing a trick on him when he gained weight.

The 'Informant!' actor - who raises three children with wife Luciana Bozan Barroso - was so unwilling to admit he had put on weight he convinced himself his actor pal had paid someone to alter all his clothes so they didn't fit.

Matt Damon says gaining weight for his new movie is the most fun thing he's ever done. The "Informant!" actor - who plays overweight Mark Whitacre, an agricultural businessman who becomes an FBI informer, in the film - piled on 30lbs for the role, and delighted in gorging on calorific treats.

He said: "It was very, very easy to gain the weight. It was very, very fun, probably the most fun time I've had working because I didn't have to go to the gym after work and I just ate everything I could see."

Emily Blunt is going to "dance boot camp." The "Young Victoria" star is set to appear in "The Adjustment Bureau" alongside Matt Damon and says that playing a ballerina will provide a new challenge for her.

She explained: "I'm going to dance boot camp. I'll never be at the same standard as a professional, but hopefully I'll be able to do a little bit."