05/09/2012 09:13 am ET Updated Jul 28, 2014

'Dancing With The Stars': 13 Celebrities Who Have Lost Weight Competing

Hours and hours of training go into each performance on "Dancing With The Stars," as week after week, celebrities and their professional dance partners compete for America's votes.

While all that practice certainly comes in handy when it's time to perform the next foxtrot or rumba or waltz, all that training has also helped a number of stars off of the dance floor. Viewers have witnessed some astounding transformations over the past 13 seasons (and during this one, too!) as celebrities have toned and trimmed their way to healthier weights.

It's no surprise. Dancing is a serious cardio workout that also builds muscle and increases flexibility, balance and agility, Fabio Comana, exercise physiologist and senior fitness education for the National Academy of Sports Medicine, told HuffPost last month.

But a "Dancing With The Stars"-fueled slim down is becoming so common, stars are now signing up for the reality TV show to dance with specific weight-loss goals in mind, reports ABC, thanks to the inspiration drawn from famous (and slimmer!) faces of seasons past.

There have been many transformations over the seasons of "Dancing With The Stars," but here are a few of the most dramatic.

'DWTS' Weight Loss

For more on fitness and exercise, click here.

For more on weight loss, click here.

For more on "Dancing With The Stars", click here.