Blunt, who plays a ballerina in the film, claimed that it was the most challenging role of her career due to the amount of physical strain the part demanded of her.
"It's an endurance test physically because you are effectively living the life of an athlete for months on end," Blunt explained to the Daily Star. "I ate nothing but chicken, salad and veg, which I hate - because I eat like a truck driver.
"I found it very hard because I never danced before. It was so alien to me."
The Adjustment Bureau, which also stars Matt Damon and Terence Stamp, will be released in cinemas March 4, 2011.