Celebrity contestants on " Dancing With the Stars" shed serious pounds each season by shaking, shimmying and dancing their hearts out night after night on the dance floor.

Ricki Lake, Nancy Grace, Rob Kardashian and Chaz Bono all slimmed down during the show's 10-week season, following in the footsteps of stars from seasons' past such as Kirstie Alley, Kelly Osbourne, and Marie Osmond.

"It is so rewarding to see your partner start one way and then three months later be a completely different person, like with Kelly. It's amazing," "Dancing With the Stars" pro Louis van Amstel said today on " Good Morning America."

Credit: Adam Larkey/ABC

Van Amstel starred on seven seasons of the hit ABC show and trained partner Kelly Osbourne as she transformed her body into a size 2, dropping 40 pounds. Now, the three-time, world-dance champion and GoodMorningAmerica.com blogger is out with LaBlast, a five-disc DVD set of fitness-based dance workouts that bring the ballroom and all of its benefits to you.

"It's really a workout in disguise because you're working out for an hour but you don't feel like it," van Amstel said. "You just keep going on and dancing, and that's the secret of losing weight, by doing dance."

Blending classic dance techniques such as the Cha Cha, disco and jive into one calorie-burning workout, van Amstel says you'll work the waistline, legs and upper body, all in your living room.

"In the first three DVDs you learn all the dances, and then in [DVDs] four and five, you can work the specific body part … all through dance," he said.

You don't need a partner or a real sense of rhythm to reap the rewards. (You don't need the sequins or spray tan that you do on the show, either).

"LaBlast is partner-free and you can still learn all these dances," he explained. "Level 1 is for the absolute beginner or for the person really needs to lose 50 or 60 pounds, or simply feels they can't do it because they're uncoordinated. Anyone can dance. If you're willing to give up control, you can dance."

Here's a roundup of "DWTS" stars who have lost weight on the show.

Here are more exercise tips to stay on track in the New Year.