“A waist trainer is a device similar to a corset, typically manufactured from elastic material,” explains Kelley Vargo, MS, MPH, CSCS, a certified strength and conditioning coach. Often, waist trainers feature
a velcro strap that can be cinched around the waist, or bra-style hook and eyes that can be progressively tightened. The intention behind wearing one? “To create a slimmer waist and an hourglass figure,” Vargo says. If worn consistently over time, waist trainers can create a pretty extreme effect (think: Kim K at the Met Ball last year).