Flops That Make You Fit?

July 9, 2008— -- Can a type of footwear once associated with hippies be the new key to toned bodies?

If numbers tell us anything, then there are a lot of men and women who are banking on the FitFlop, dubbed by the manufacturer as "the fastest-selling fitness shoe in history," and as a potential saving grace for busy women and men, looking to tone up and trim down.

FitFlops have sold more than 1 1/2 million pairs since they debuted in the U.S. and the United Kingdom a year ago, where they were met by salivating mobs of women. At around $50 a pop and higher, it looks like their makers have hit on something big.

"I'm from a beauty background, so I know that women want something they can easily use that fits into their schedule," said Marcia Kilgore, founder of Bliss Spa and FitFlops.

Kilgore said she got the idea for the sandals while talking to some of her friends.

"I thought, well, 'What about a flip-flop with a gym built-in? A flip-flop that tones your legs when you walk around in it,'" Kilgore said.

So, with the help of two scientists from London's South Bank University, her dream fitness shoe arrived, and in good time. Increasingly, fitness classes that utilize balancing during weight exercises, as well as barefoot exercises to better activate the leg muscles, are becoming more and more common in gyms across the country. Companies, such as Nike, even have shoes that simulate walking barefoot. According to Kilgore, her sandals tap into that idea.

"When you step in the center section, which is quite soft, the eversion rate of your foot, which is how fast your foot rolls over, slows down on this midsole because there's a little bit of wobbling going on," Kilgore said. She claims that by causing the foot to step that way, the FitFlop activates the buttocks, hamstring and the thigh muscles, giving you a little workout with every trip out of the house.

This stylish fitness shoe for women claims to tone thighs, burn calories and erase cellulite. They were an instant hit, receiving buzz on television shows across the U.K. and the United States. (Don't worry guys, men's versions will be available in the U.S. later this summer.) Recently they landed on one of pop culture's most coveted lists, Oprah Winfrey's "Top Picks for Summer."

But, are these shoes more hype than science? ABC News brought the FitFlops to a running coach and a sports medicine doctor for their evaluation.