1 of 12
Less than six months after giving birth to daughter Nahla Ariela on March 16, the Oscar winner was back in movie-star shape – thanks to 60-minute sessions, five days a week, with a trainer.
2 of 12
She gained 50 lbs. while pregnant with twins Max and Emme (who were born Feb. 22). Lopez took it easy for four months – then started working out six times a week with Gunnar Peterson, who trained her for a charity triathalon in September.
3 of 12
To get her famous abs back, Spears, 27, hit the gym at least 3 days a week for aerobics, jogging and weight training with a trainer.
4 of 12
JENNIFER LOVE HEWITT
"This was my year to try to feel better," says Hewitt, 29, who started strength training and running up to five times a week.
5 of 12
"I never felt my weight get out of hand," the singer said about carrying son Max Liron, born Jan. 12, 2008. So she waited until mid-March to exercise with trainer Tee Sorge. "I do the treadmill, I box, and I do a lot of weights. I feel so much better when I work out." She also burns calories breast-feeding – and by summer, Aguilera was back in body-hugging dresses.
6 of 12
The singer has been showing off a tighter, toned body – thanks to her regime of water aerobics – and changed her diet, even taking Oprah Winfrey on a tour of her refrigerator. Part of Carey's new meal plan? Baked clams, rice, berries, swordfish and vegetable soup – "Always a winner," she says. "You can eat as much of this as you want and you won't gain one pound!"
7 of 12
The 26-year-old Knocked Up star has been working out with trainer Harley Pasternak to prepare for his superhero role in The Green Hornet.
8 of 12
By going on NutriiSystem, Osmond, 49, lost 40 lbs. "I was a size 14 and I cut it down to a size 4!" she boasted. "I had been putting on 5 lbs. a year – it's so easy to do! So I decided to only buy healthy food: salads, fruit and veggies."
9 of 12
Coleman, 28, lost 15 lbs. on Dancing with the Stars – and now does "spinning, running, hiking – anything fun!"
10 of 12
She lost 28 lbs. on Medifast, then started jogging. "My butt and thighs look great!" says the 39-year-old.
11 of 12
The former Saturday Night Live star, 39, lost around 100 lbs. by cutting back on booze and "eating better," he has said.
12 of 12
Latifah, 38, lost more than 5 percent of her body weight with Jenny Craig and daily elliptical workouts.