Watch out, Jennifer Lopez and Kim Kardashian! When Fergie walked the red carpet at the Jan. 31 Grammy Awards in LA, she wowed with her rock-hard body, killer curves and the hottest butt in Hollywood. Her figure was especially impressive considering that earlier last year the Black Eyed Peas singer was still trying to shed the 17 pounds she gained to play a voluptuous prostitute in the movie musical Nine. But dropping the extra weight didn't require extreme dieting. Fergie simply turned to Carrie Wiatt, her nutritionist and the creator of Diet Designs, for a healthy lifestyle plan. "Fergie restricts her carb intake at night," Wiatt reveals to Life & Style. "That means avoiding carbs at dinner and doubling up on veggies -- and having three small snacks during the day to prevent overeating at mealtimes." By sticking to 1,600 calories daily, Fergie was able to drop the pounds while amping up her assets with frequent workouts focusing on her booty.

Her trainer, Don Brooks of Don-A-Matrix Training tells Life & Style he has Fergie tighten and squeeze her glutes while walking at an incline on the treadmill or up a hill, and while doing simple exercises like single-leg hip raises. And her menu helps Fergie get through rigorous workouts. "She usually opts for hunger-blasting ingredients like protein-rich chicken, omega-3-rich pine nuts, fiber-filled grapefruit and healthy fats from avocado," says Wiatt, who includes these ingredients in Fergie's Diet Designs main meals.

For more on Fergie's diet and fitness routine, pick up the latest issue of Life & Style, and for more details on celebs who have packed it on or shed pounds for a movie, check out ThatsFit.com.

Photo Credit: Retna