Keira Knightley has slammed the Hollywood system for encouraging actresses to lose weight. The skinny star insists she is curvy compared to most of the leading ladies she goes up against at auditions - and has called on studios to take a more responsible attitude. She says, "I'm twice the size, height and everything else of most of the other actresses who are going for an audition. It's mad, isn't it? When you realise that even at my size I'm one of the largest there. "It's at the point you start to say, 'I don't think it'd be healthy for me to stay here much longer.' "Are we surprised that there are people out there who feel they have to lose weight? "It's shocking for young girls. There is a lot of pressure - it's like you've got to be perfect."