Amanda Seyfried wouldn't gain weight for a role.

The 28-year-old actress insists it would be ''unhealthy'' to try and change her body shape for a part and finds it easy to maintain her slender figure, even when she indulges in her cravings for calorific treats.

Asked if she would gain 20 kilos for a role, she said: ''No. That's so unhealthy. I wouldn't want to lose or gain any pounds. I don't want to inflict that on my body, it would make everything out of sync. You've got to take care of your body.

''Sometimes, like everyone, I eat badly: I love sugar and cheese. I don't have to struggle to stay slim, but because I'm so short, you see it immediately. Luckily, I lose the weight pretty quickly, I do a lot of exercise, I run and I walk, with my dog of course. I'm sure that with kids, it would be even easier!''

The 'Les Miserables' star also admitted she isn't afraid to ''beg'' for a role she wants and once auditioned in disguise after she had been turned down for a part.

She told France's Grazia magazine: ''Three years ago, a director told me I wasn't made for a certain role and he didn't want to meet me. I called up the casting director and begged him to let me have a trial. I went and he once again told me it was a no.

''I contacted an acting coach, which I never normally do, and went back in a different outfit and did the audition in a different accent, begging them to see me another time. They gave the role to someone else: but it didn't matter, I just wanted to be sure I had done my best. It's my biggest strength: not being scared of doing castings that some actresses think they're above. I had five auditions for 'Les Miserables!' Of course, I would never go as far as getting undressed to land a role...''