Gaining weight is not only easy but a lot of fun, according to Hollywood golden boy Matt Damon, who had to assume larger proportions for his role as a corporate honcho in 'The Informant!' 'It was very, very easy to gain the weight,' Damon said Monday at the Venice film festival ahead of the out-of-competition screening of Steven Soderbergh's new movie. 'It was very, very fun, probably the funnest time I had working, because I didn't have to go to the gym after work and I just ate everything I could see,' Damon told reporters. 