PHOTO Kim Kardashian flaunts her tiny midsection in a waist trainer, but is it safe?

Between regularly tweeting about trying to shed the stubborn final pounds she gained during pregnancy to posting a (Photoshopped) throwback picture from “#SkinnyDays, it’s clear Kim Kardashian’s favorite subject these days is her weight-loss mission.

But, because simply losing weight isn’t good enough, Kim’s also using a “waist trainer” similar to the one Khloe Kardashian showed off in May. She posted this picture yesterday, adding, “#hourglass #waisttraining #nophotoshopnecessary #whatawaist.com @premadonna87”

Besides the Kardashians — who almost certainly have a pretty lucrative endorsement deal with WhatsAWaist.com, even though Kim misspelled it — Jessica Alba’s also praised the idea of “waist training.”

“It was brutal, it’s not for everyone,” the Sin City 2 star told Net-a-Porter last year of the extreme measure she took to regain her pre-baby body. “I wore a double corset day and night for three months. It was sweaty, but worth it.”

However, the praise is far from universal — especially when when medical professionals are brought into the conversation.

“Corset training can restrict any type of movement in your midsection,” Dr. Nicole Florence, Co-Director of Memorial Weight Loss and Wellness Center at Memorial Medical Center, told Ebony this year. “It can restrict your lungs, which can cause lung infections and other lung problems, as well as restrict your bowels, which can cause constipation. It can also cause bruising and rib pain.”

University of Massachusetts obesity expert Sherry Pagoto, Ph.D., said in an email to Huffington Post that marketing waist trainers is really just “aiming to take advantage of (and money out of the pockets of) people who need guidance on how to develop healthy lifestyles to reduce their risk for disease.”

Both doctors concluded “waist training” is one fad to skip.