Who has the best body after baby?

WINNER
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.

The actress was spotted at a spinning class just a day before giving birth to daughter Sunday Rose on July 7, and was back on the bike three weeks later. She then showed off her famously slim figure on Sept. 8 in London – just two months after giving birth!

Admitting that she "never felt less sexy" than when she was pregnant, Alba wasted no time after the June 7 birth of daughter Honor Marie. Thanks to hour-long workouts, five or six days a week – plus a strict diet of 1,700 calories a day, according to trainer Ramona Braganza – the actress (at the ALMA Awards) dropped 25 lbs. in three months.

"I felt great physically," Richie told PEOPLE of gaining pregnancy weight. "It wasn't something I thought about. It was more like, 'What am I going to wear?' When I stopped fitting into my jeans, I wore leggings." And after Harlow Winter's birth Jan. 11, her body bounced back naturally. "People asked me if I work out. I'm like, 'I don't know what kind of time you think I have!'"

The singer – who admitted to Harper's Bazaar that her weight is "an ongoing battle and it's a nightmare" – looked lean and chic less than two months after the Aug. 21 birth of her second son, Zuma Nesta Rock. "It's so much work [after pregnancy] to get the weight off," she has said. "If you just do it, it comes off."

"I never felt my weight get out of hand," the singer said about carrying son Max Liron, born Jan. 12. 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.

She gained 50 lbs. during pregnancy, but Lopez didn't let that get in the way of a glam night in New York, just weeks before the Feb. 22 birth of twins Max and Emme. She 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.