linda evangelista says she has pah. what’s that?

evangelista took to instagram on wednesday night to explain why she’s rarely been seen in public over the last five years. she claimed that she developed paradoxical adipose hyperplasia (pah) as a result of coolsculpting, a procedure that freezes fat cells, allowing the body to eliminate them. evangelista said that in her case, coolsculpting “increased, not decreased, my fat cells and left me permanently deformed after undergoing two painful, unsuccessful, corrective surgeries.” she says the risk of developing pah was not disclosed to her in advance, and that the diagnosis “has not only destroyed my livelihood, it has sent me into a cycle of deep depression, profound sadness, and the lowest depths of self-loathing.”

the procedure is a popular one: in 2016 it was used in 3,218 places around the world; in just two years that number increased by 76 per cent . it’s been promoted by celebrities including khloe kardashian , kris jenner , debra messing , molly sims , sonja morgan and malin ackerman .

while pah, the side effect that evangelista says left her “disfigured,” has been reported, it was seen as very rare. it was first reported in a 2014 study published in jama , which said it had an incidence of 0.0051 per cent. (that study also said that “no single unifying risk factor has been identified,” but that pah appeared to be more common in men than women.) people with pah report that rather than getting smaller, the area treated with cryopolysis get bigger, leaving what participants in one study described as a “painless, visibly enlarged, firm, well-demarcated mass” under the skin. it’s sometimes called the “stick of butter” effect: rather than abdominal fat settling all around the waist, for instance, all of that fat is concentrated in what looks like a stick of butter in one spot.

dr. rohan bissoondath, medical director and founder of calgary’s preventous collaborative health and preventous cosmetic medicine (and occasional contributor to healthing ), has both performed coolsculpting on patients and received the treatment himself. he says he still considers it safe. “we have four coolsculpting devices and have performed thousands of treatment cycles with no cases of pah to date,” he told healthing.

evangelista says she wasn’t warned about the possibility of pah. as of thursday, the coolsculpting website lists several possible side effects , including pah: “though rare, some additional side effects such as paradoxical hyperplasia, late onset pain, freeze burn, vasovagal symptoms, subcutaneous induration, hyperpigmentation and hernia may also occur.”

a 2015 study , this one in the journal lasers in surgery and medicine, called pah as a result of cryolipolysis an “underreported entity.” it found that pah happened in 1 in 211 treatments, or 0.47 per cent — 100 times greater than what coolsculpting was reporting at the time.

and a 2018 study published in plastic and reconstructive surgery said that pah was estimated to occur in 1 out of every 4,000 treatment cycles — that is, there was a 0.025 per cent chance it would happen. (a low number, but still higher than the 2014 assessment.) but the study’s authors noted that within the parameters of their study, it appeared to be more common: they saw it in 1 out of every 138 treatments, or 0.72 percent.