"I was a real tomboy. My teacher used to write on my report card 'Michelle is one of the biggest girls in class'" the Mirror quoted her, as saying.
"All I wanted to be was to be one of a petite little girls but my mother always cut my hair in a pixies and there was nothing feminine about me," she added.
Michelle, who is playing an ancient witch trying to restore her youth and beauty in new movie Stardust, said that she resorted to a complete makeover in weight and wardrobe to get into acting.
"A friend knew a beauty pageant where a judge was an agent who signed girls. That was my ticket," she said.