Michelle Williams felt she had been "reborn" when she gained weight to play Marilyn Monroe.

The 32-year-old actress worked hard to transform herself by perfecting the late screen icon's mannerisms ahead of her role in 'My Week With Marilyn' but admits she needed a long time to prepare for the physical changes the part needed.

Speaking about her weight gain, she said: "Unfortunately, it went right to my face. So at some point it became a question of, 'Do I want my face to look like Marilyn Monroe's or my hips?'

"It felt like being reborn. It felt like breaking my body and remaking it in her image, learning how she walked and talked and held her head. None of that existed in my physical memory, and I knew I needed as much time as possible to make it part of me."

Michelle also spent six months researching Marilyn, studying her old movies and photographs, reading biographies, diaries, and old letters and tracking down old clips on YouTube, likening her immersion in the star to her previous experiences of studying for exams.

She added in an interview with America's Vogue magazine: "I'd go to bed every night with a stack of books next to me. And I'd fall asleep to movies of her. It was like when you were a kid and you'd put a book under your pillow hoping you'd get it by osmosis."