Just when you thought she couldn't get any skinnier, KEIRA KNIGHTLEY steps out looking thinner than ever.

The super-svelte star took to the red carpet last night with co-star SIENNA MILLER for the premier of their new film, The Edge of Love.

But despite denials she is suffering from an eating disorder the actress appeared uber-skinny, even next to super-slim Sienna.

Just two days ago Keira's mother spoke out in defense of her daughter, denying the actress is anorexic and blasting the media as "playground bullies"