The image of Ginger Rogers and Fred Astaire floating across a room is still iconic seven decades after they first graced a screen. And yet for some reason most of our own generation has never associated Ginger's perfect body with the healthy benefits of ballroom dancing. For that, it took John O'Hurley ‑- that dapper, funny gentleman from Seinfeld ‑- who very publicly lost 15 pounds on this summer's sleeper hit, Dancing with the Stars. It turns out that fox-trotting, twirling and swinging to the beat can be legitimate ways to lose weight.

If the only times you've ever danced with a partner are at proms and weddings, you might need a little patience before the ballroom becomes your gym alternative. Beginner classes start off slowly: You can spend the entire first hour doing nothing but the basic step, first in front of the mirror and then with rotating partners, and the only sweat comes from your palms (or, unfortunately, your nervous partner's). But soon enough, once you learn a turn and a variation or two, you'll be moving continuously through entire songs. It's this uninterrupted movement that raises your heart rate while you're too busy thinking about the steps and having fun to notice. According to the iVillage calorie calculator, a 140-pound person can burn an average of 349 calories in an hour of fast social dancing and 191 calories in slower styles. Swing, salsa and quickstep are obvious fast choices. However, with the slower styles such as tango or traditional ballroom (waltz, cha-cha and foxtrot), it's easier to dance longer without stopping.