New Year, New You: The Diet Secrets of Sexy Stars

Jan. 3, 2012 -- A new year brings new resolutions to get fit and stay in shape, especially if you've recently opened a magazine, watched a movie or tuned into TV, only to see another A-list leading lady with a figure to die for.

Just how do Hollywood celebrities manage to look so hot, all the time?

Us Weekly magazine tracked down the experts to get the sizzling, body-slimming secrets of stars like Miranda Kerr, Katy Perry, Kim Kardashian and more.

Check them out here, and try them for yourself.

How does singer Katy Perry keep her curves, and still look like a "teenage dream"?

Circuit training, jumping rope and sticking to meals rich in dietary fiber are the 27-year-old's secrets, according to Us Weekly.

"Katy Perry loves to wear those body baring, skimpy costumes on stage, so she trains really hard with Harley Pasternak in LA," Jaimee Zanzinger, executive editor at Us Weekly, told "Good Morning America."

"They circuit train together," she said of Perry and Pasternak's plan. "So she'll go from hitting the treadmill to the jump rope."

Click HERE to try Haley Pasternak's full body toning moves yourself.

Meanwhile, reality TV star Kim Kardashian makes jaws drop every time she steps out, from the red carpet to the clubs to even the new bangs she debuted this New Year's Eve.

For 31-year-old Kardashian, steering clear of sugar, eating organic foods and skipping water breaks while exercising are the secrets to her body success.

"When it comes to workouts, Kim Kardashian takes no prisoners," Zanzinger said. "She goes from one move to another and really mixes it up. She runs, she does lunges and pull-ups. She focuses on moves that will allow her to keep those curves while blasting that body fat."

Hollywood's blonde bombshell, Amanda Seyfried, also has a body to kill for, but the 26-year-old actress admits she has to fight hard to keep it that way.

"Amanda is refreshingly honest about her weight," Zangiger said. "She says she's not one of those skinny girls that stays skinny. She has to really work at it."

Seyfried, like Katy Perry, also counts trainer Harley Pasternak as one of her secret weapons, but she also likes to try workout classes with her friends, and take her workout outdoors, on hikes with her dog.

When it comes to eating, the actress credits a diet high in fiber and protein-rich meals - a favorite snack is Greek yogurt - and also does not deprive herself of a food item she really wants.

Seyfried's fellow young actress, Olivia Wilde, made a name for herself on Hollywood's A-list body list by appearing in a skintight bodysuit in the 2010 box office hit "Tron: Legacy," but the experience changed the actress's body philosophy.

"Olivia has a really healthy attitude about dieting. She doesn't do it," said Us Weekly's Zanzinger. "Over the past few years she stopped eating carbs so she could fit into the skintight suit that she wore in the movie "Tron," but she said it really stressed it out her so much that it ended up working against her goal."

Today, Wilde, 27, maintains her "Tron"-worthy figure by sticking to a vegetarian diet, indulging in healthy snacks like miso soup and mangoes, and taking hula-hoop classes.

New celebrity moms like Kate Hudson, Mariah Carey and Victoria Beckham all made headlines recently by quickly bouncing back to their pre-baby shape, but supermodel Miranda Kerr may have outshone them all.