Fergie’s looking fit in her striped two-piece on the cover of the July 2009 issue of Allure Magazine, but getting her svelte figure back into shape after filming her role in the upcoming film Nine wasn’t easy.

Last year, director Rob Marshall asked the Black Eyed Peas songstress to gain weight in order to play the part of Saraghina, a prostitute, in the movie which is due to hit movie theaters in November. Ferg says gaining 17 pounds for Nine allowed her to order lots of foods that were “fried and full of fat” — and she did it with the help of Oscar-winning co-star Penelope Cruz.

“We were eating our brains out,” Fergie told Allure.