The Pirates of the Caribbean star denies suffering from anorexia but says close family members have been affected.
She says: 'I've got a lot of experience with anorexia - my grandmother and great-grandmother suffered from it, and I had a lot of friends at school who suffered from it, so I know it's not something to be taken lightly and I don't.
'It's quite interesting because it's normally high-achieving women who suffer from it because I guess they are control freaks.'
She adds: 'I'm not saying there aren't people in the film industry that suffer from it, because I am sure that there are, but I am not one of them.'
But the 21-year-old, who shot to fame in movie Bend it like Beckham, has admitted to feeling pressure to maintain her small frame.
She says: 'I'm a skinny person and I remember recently when I went into clothes shops in LA, even I couldn't fit into some of them. It's worrying to see people pushing themselves to terrifying lengths to achieve what's perceived as being beautiful today.'
