American Idol judge Kara DioGuardi put in some long hours in the gym to strut her bikini on stage during the season 8 finale of the hit Fox show. And that's nothing out of the ordinary for the songwriter, who tells Women's Health that she hits the gym about four times a week, running two miles or 25 minutes of cardio. "Boxing, treadmill, step-ups, walking lunges, sprints... I mix it up," she says. "And weight training is important as you get older. You build muscle, which burns fat when you're at rest." And in addition to drinking at least "two huge bottles" of water a day, she eats plenty of veggie stir-fry, adding that "the more roughage you eat, the more it fills you up."