06:06 PM EDT 08/24/2014
Originally posted 11/14/2011 02:20PM
She added a few pounds, had the blonde wig, and spent hours in makeup each day to play Marilyn Monroe in the upcoming film My Week with Marilyn. But Michelle Williams had to learn to move like the Hollywood legend, too.
"I wasn't watching what I ate, let's put it that way," Williams, 31, told PEOPLE Sunday, at the film's New York premiere, about her physical transformation, which also included some helpful wardrobe tricks that helped her jiggle a bit more.
"The costume designer and Michelle came up with some great stuff," said director Simon Curtis. "But an awful lot is Williams's understanding of the way Marilyn walked, and the way Williams herself took on the wiggle."
Top 10 News Categories
The most buzzed about stars this minute!
Treat Yourself! 4 Preview Issues
More On PEOPLE.com
Got a News Tip?
Send it to our People.com editors!