Though waist training has been around for centuries, it’s undeniable that Kim Kardashian and Amber Rose popularized it in the past two years via their enthusiastic IG posts. Users say they can slim your waist one to four inches, both immediately and longer term, when used consistently. But it’s not necessarily that simple. Want to try it? We talked to Ruben Soto, CEO of HourglassAngel.com, to find out what you need to know before you cinch up.

Feel the Squeeze

Waist trainers work by physically compressing your waist and making you sweat, which sheds water weight. There is a lot of speculation about the long term effects. When used daily for several weeks, they have been found to actually displace your organs to make your abdomen smaller. But there is no evidence that the effects last indefinitely.

Size Matters
It’s important to buy a waist trainer that is comfortable and effective, so pull out measuring tape and use the company’s size guide to order. “When in between sizes, we actually recommend that you size up rather than down,” Soto says. “A waist trainer that is too small will be extremely uncomfortable and will not give you the most flattering results.”

Time Matters, Too 
Experts say you should work up to wearing a waist trainer eight to ten hours a day to see real results. But start with just a few hours at a time until you get comfortable wearing it.

It’s Hard to Put On

Give yourself plenty of time to put it on the first time. Most have hook and eye closures, and Soto offers this advice for getting it on: “Start by fastening from the bottom up, but holding it above your waistline. Pull the waist trainer down over your waist as you fasten each hook.

Exercise Is a Must
Not only will a waist trainer not cinch in your waist long term if you don’t exercise (and eat well), but wearing it for long periods of time without working out can actually cause you to lose the muscle tone you already have. Do abdominal exercises at least three times a week for the best results.

It Might Impact Your Appetite
So, it turns out that wearing something tight around your abdomen makes you less likely to eat a bunch. It might pay to monitor your caloric intake to be sure you’re not jacking up your diet.

Listen to Your Body
If it doesn’t feel right, take it off! “Don’t continue wearing your waist trainer if you experience any numbness, pinching or pain,” Soto says. “It should never be painful or restrict your breathing. If it does, consider another size.”