The 30-year-old Albert Nobbs starlet has lost weight for her current role as Natasha Kampusch in 3096, based on the real-life story of Austrian Kampusch kidnapped aged 10 by Wolfgang Priklopil and held in captivity for eight years (3,096 days).
Yesterday, the Northern Irish star revealed the extent of her frail figure in a sheer blue floral frock as she graced the red carpet along with Burton, Helen Bonham Carter and Lauren Laverne.
Matthew McConaughey has also been losing weight for a film role and was recently spotted looking gaunt and emaciated, as he prepares to play Texan electrician Ron Woodroof who contracts AIDS through drug abuse in the late '80s in The Dallas Buyer's Club.
Filming for 3096 began back in May and the movie is set for cinematic release around February 2013.
See more pictures of stars losing and gaining weight for movie roles here:
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