While many women have one or two—or six or seven—tummy-shaping undergarments in their dresser drawers, many of us probably think of restrictive corsets as a relic of the past.

But scroll through the Instagram accounts of celebrities like Jessica Alba and Kim Kardashian, and it’s clear that some women in the spotlight are trying to bring back the trend. They tout the restrictive “waist training” devices—basically a super-tight belt that fits across your entire midsection—as the secret to getting impossible hourglass curves, even soon after giving birth.

The pictures are impressive, but will these corsets really leave you with a toned waistline once you take them off?

Not exactly, says Dr. Victor Prisk, an orthopedic surgeon with Allegheny Health Network who also knows a little something about body shaping; he’s a former gymnast who is now also a competitive bodybuilder.

“Being aware of the fact that you’re trying to lose weight and get in shape, and having something to remind you of that—there’s that purpose and that’s great,” he says. “But there’s no evidence to support that they actually do work.”

Prisk says using waist-training devices may produce some short-term effects. He’s noticed a difference in fellow bodybuilding competitors who have used them. They can also be a useful tool to force better posture, and as a restrictive reminder that you should sit and stand up taller.

Plus, Prisk says, there’s another consequence—or benefit, depending on your goals—of being constrained all day: “You can’t eat as much when you have it on, and you tend to get fuller faster.”

But for some people, regularly wearing undergarments that compress the midsection carrie significant risks. If you’re prone to problems with acid reflux, or you have a hiatal hernia, the extra abdominal pressure could trigger bigger reflux issues.

Too much wear could also end up doing the opposite of toning up that six-pack.

“There isn’t really evidence to say wearing them will cause back problems, but I think excessive wear could lead to an overreliance on it or a weakening of the core,” Prisk says.

Focusing on shrinking the size of your midsection can be smart, according to Prisk, as the visceral fat we carry around the waist is particularly bad stuff that can cause health problems. But at the end of the day, Prisk says old-fashioned hard work at the gym and smart food choices are the ways to shape the look—and health—of your belly.

“It certainly doesn’t circumvent the need to work on core strength and conditioning, or the need for a healthy diet and to get regular exercise,” he says.