Katy Perry used trainer Harley Pasternak's 5 factor diet, 5 well-portioned, well-balanced meals a day to get into great shape for her wedding. (Once a week you get a cheat day!) She also works out at least five days a week and does 25 minutes of circuit training. Click here to learn more!

Anne Hathaway is determined to be an amazing Catwoman — even if it means her normal life is suffering a bit. According to the 28-year-old actress, who's been busy shooting The Dark Knight Rises — she's been eating a strict diet and working out ALL THE TIME. Click here to find out what she ate!

Since giving birth to twins, Mariah Carey has been following the Jenny plan -- in addition to a strict workout regiment. "She works out a minimum of two hours a day, seven days a week now," a source tells Star magazine. Click here to learn more!

Jennifer Aniston does at least 20 minutes of cardio a day and was seen doing up to two hours on a treadmill while filming Just Go With It. Jen was once a Zone dieter, but now she keeps it healthy with fruit and yogurt for breakfast, salad for lunch, and broiled fish and steamed veggies for dinner. Click here to learn more!

If you've ever envied Jennifer Lopez's big ol' butt (and we mean that in a GOOD way!) well, now you can have it! Gunnar Peterson shared one of her sample routines with HollywoodLife.com — and it isn't as complex as we thought. Dare we say it? We may even be able to try it ourselves! "I'm a big fan of a lot of different movements," Gunnar told us. "[I do] big sequences back to back spliced with high intensity cardio stuff, which could be anything from a rower, to a stair climber, to a treadmill." Click here to get the full workout!

Just HOW does Kim Kardashian manage to look so damn good all the time? Trust us, it isn't easy — but her workout routine IS doable! Kim's trainer, Gunnar Peterson (who also works on J.Lo's fab booty!) mixes strength moves — alternating upper and lower body exercises with core work — with cardio and wa-la! You can get the Keeping Up With the Kardashians starlet's hot bod! Click here for Kim's exact workout!

We've got the scoop from NutriFit founder Jackie Keller on how her clients like Jessica Alba, Susan Sarandonand Uma Thurman fight the fat and how you can too! Check out how you should be eating this week to prepare for the rest of the year by clicking here!

Jordin Sparks decided to take control of her life and get healthy. She didn't go crazy, though. No crash diets or exercise addictions for this girl. Instead, she took baby steps. "I would walk, and that turned into jogging, which turned into hiking a mountain and going to the top, which turned into Zumba classes, then 'let's see if there's a trainer.'" Click here to see more of how she did it!

Want a new body in 2012? We have all the diet and fitness tips from the hottest A-listers in Hollywood!

If you're anything like us, you pledged to eat healthy and get fit in 2012. Now the new year is underway and it's time to accomplish those goals! From Kim Kardashian to Jennifer Aniston, we scoped out the best diet and fitness tips around, making it easier than ever for you to get that perfect bikini body you've always wanted!

Katy Perry used trainer Harley Pasternak's 5 factor diet, 5 well-portioned, well-balanced meals a day to get into great shape for her wedding. (Once a week you get a cheat day!) She also works out at least five days a week and does 25 minutes of circuit training. Click here to learn more!

Anne Hathaway is determined to be an amazing Catwoman — even if it means her normal life is suffering a bit. According to the 28-year-old actress, who's been busy shooting The Dark Knight Rises — she's been eating a strict diet and working out ALL THE TIME. Click here to find out what she ate!

Since giving birth to twins, Mariah Carey has been following the Jenny plan -- in addition to a strict workout regiment. "She works out a minimum of two hours a day, seven days a week now," a source tells Star magazine. Click here to learn more!

Jennifer Aniston does at least 20 minutes of cardio a day and was seen doing up to two hours on a treadmill while filming Just Go With It. Jen was once a Zone dieter, but now she keeps it healthy with fruit and yogurt for breakfast, salad for lunch, and broiled fish and steamed veggies for dinner. Click here to learn more!

If you've ever envied Jennifer Lopez's big ol' butt (and we mean that in a GOOD way!) well, now you can have it! Gunnar Peterson shared one of her sample routines with HollywoodLife.com — and it isn't as complex as we thought. Dare we say it? We may even be able to try it ourselves! "I'm a big fan of a lot of different movements," Gunnar told us. "[I do] big sequences back to back spliced with high intensity cardio stuff, which could be anything from a rower, to a stair climber, to a treadmill." Click here to get the full workout!

Just HOW does Kim Kardashian manage to look so damn good all the time? Trust us, it isn't easy — but her workout routine IS doable! Kim's trainer, Gunnar Peterson (who also works on J.Lo's fab booty!) mixes strength moves — alternating upper and lower body exercises with core work — with cardio and wa-la! You can get the Keeping Up With the Kardashians starlet's hot bod! Click here for Kim's exact workout!

We've got the scoop from NutriFit founder Jackie Keller on how her clients like Jessica Alba, Susan Sarandonand Uma Thurman fight the fat and how you can too! Check out how you should be eating this week to prepare for the rest of the year by clicking here!

Jordin Sparks decided to take control of her life and get healthy. She didn't go crazy, though. No crash diets or exercise addictions for this girl. Instead, she took baby steps. "I would walk, and that turned into jogging, which turned into hiking a mountain and going to the top, which turned into Zumba classes, then 'let's see if there's a trainer.'" Click here to see more of how she did it!

Want a new body in 2012? We have all the diet and fitness tips from the hottest A-listers in Hollywood!

If you're anything like us, you pledged to eat healthy and get fit in 2012. Now the new year is underway and it's time to accomplish those goals! From Kim Kardashian to Jennifer Aniston, we scoped out the best diet and fitness tips around, making it easier than ever for you to get that perfect bikini body you've always wanted!