Toning shoes are all the rage, promising to firm up a mushy tush, tone your thighs and help you burn more calories than you would with plain old walking. But they may not be the magic bullet you’ve been dreaming of.

Fitness shoes are designed with a rounded bottom—similar to the stability balls you’ll find at the gym—to create instability. This is supposed to make your muscles work harder with every step you take. According to Skechers—the makers of Shape-ups—wearing toning shoes may give you stronger leg and butt muscles, help you burn more calories and improve your posture.

However, some experts say there aren’t any long-term benefits to these popular fitness shoes. According to Phillip Vasyli, podiatrist and founder of Orthaheel footwear line, “toning shoes make it harder to walk distances and potentially take away from a walking workout.”

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To find out whether toning shoes are actually effective, the American Council on Exercise (ACE) decided to put them to the test. The organization enlisted researchers from the Exercise and Health Program at the University of Wisconsin, La Crosse, who had active women ages 19 to 27 complete a dozen five-minute exercise intervals on a treadmill while wearing Skechers Shape-ups, Reebok EasyTone Reeinspire, Masai Barefoot Technology (MBTs) shoes or traditional New Balance running shoes. The small study found no evidence to suggest that toning shoes helped wearers burn more calories, improve muscle strength and tone or exercise more intensely.

According to ACE, toning shoes don’t offer any benefits that people looking to trim down cannot reap just by walking, running or working out in traditional athletic sneakers.

On the positive side, the mere act of purchasing toning shoes may motivate some couch potatoes to take a walk, which ACE acknowledges is an upside of the shoes. “The only real benefit of toning shoes is that they may inspire some people to get up and move around more than they would otherwise,” says Kelvin Gary, a certified personal trainer at Equinox in New York City.

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But if you really want to firm up, the key is to change up your workout—and constantly surprise your muscles—rather than simply lace up a pair of shoes. “Much like doing the same routine over and over, at first you’ll see changes, but after a while you’ll plateau and the changes stop,” explains Gary. But this can happen whether you’re wearing toning shoes or regular athletic sneakers.

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The real downside of toning shoes is believing that you’re burning extra calories, which can backfire. “People may overestimate the amount of calories they are burning due to the shoes,” notes Steve Portenga, Ph.D., director of sports psychology at the University of Denver. “If they feel that they’ve burned a lot of calories during the day, they may chose to ‘treat’ themselves, which could easily undo whatever they’ve burned from walking.”

The bottom line: If you have your heart set on nabbing a pair of shiny new toning shoes and they actually get you off the couch, then pat yourself on the back. Just be sure to wear them with eyes wide open, don’t assume you’re burning extra calories with every step and change up your workout routine regularly.

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