English actress KEIRA KNIGHTLEY has credited her Hollywood success to her body. The Atonement star, who has spent the last year battling the world's obsession with her body image, admits she owes much of her fame to her slim physique. She says: "I mean I'm an actress and it's a tool, after all. "It's pretty much all I've got. I've got whatever's in my head, my face and my voice and then there's my body, and that's it. And I do trade on that, of course I do."