What Is CoolSculpting, and Is It Safe for Weight Loss?

Every year, millions of people follow extreme diets or undergo surgery, hoping to achieve a slimmer figure.This can be a difficult goal for many reasons, so it's no surprise that the idea of banishing body fat without restrictive eating or going under the knife draws thousands of people each year to cryolipolysis, which is commonly known by the brand name CoolSculpting.

The U.S. Food and Drug Administration (FDA) approved CoolSculpting for use in 2010, and in 2019 it was the fourth most popular noninvasive cosmetic procedure in the United States.

 But in recent months, a public conversation about the safety of this procedure has become voluble, inspired in large part when the Canadian model Linda Evangelista announced on Instagram that a CoolSculpting procedure had left her “permanently deformed.”

Speaking to People magazine in February 2022, Evangelista, whose modeling career soared in the 1990s, shared that she developed paradoxical adipose hyperplasia (PAH) following the procedure.PAH is a rare side effect of the CoolSculpting process that’s characterized by areas of increased tissue volume, creating firm bulges in the skin, and health experts say that although the procedure is generally low-risk, this possible side effect is one factor patients need to consider.

Read on to find out what else you need to know about CoolSculpting.

What Is CoolSculpting?

Cryolipolysis is the process of using cold temperatures to destroy fat cells just below the surface of the skin. (The clue is in the name: “cryo” means cold, “lipo” means fat, and “lysis” means “destruction.”)

Although the term “CoolSculpting” is often used to refer to the process of cryolipolysis, it’s actually the brand name of a specific medical device used to achieve cryolipolysis. The procedure is usually carried out by a doctor, a nurse, or a physician assistant, though some medical spa professionals can also perform CoolSculpting. Check your state’s medical board for more information on who’s qualified to carry out the procedure.

How Does CoolSculpting Work?

In the procedure, a technician will apply gel pads to the targeted areas and then pass over them with the device. They may also use an applicator cup with a vacuum to draw tissue into the cup.

In either case, the goal is to apply low temperatures to specific areas of the body to kill fat cells, thereby changing the shape of the body. CoolSculpting relies on the same basic science as other fat reduction procedures like liposuction, various heat and sound-wave treatments (such as SculpSure and TruSculpt), and chemical treatments (such as Kybella).

The dead fat cells don't necessarily disappear overnight. It may take up to six months for the body to fully process and eliminate dead fat cells after the procedure, according to the CoolSculpting manufacturer.

Who Might Consider CoolSculpting?

All humans are born with a fixed number of fat cells, says Alan Matarasso, MD, a clinical professor of surgery at the Donald and Barbara Zucker School of Medicine at Hofstra Northwell in Hempstead, New York. After our teen years, the cells shrink or swell as we gain or lose weight. With procedures like CoolSculpting, the goal is to reverse those effects of time on the body.

At the same time, CoolSculpting is a strictly cosmetic procedure and isn't effective as a means of weight loss, says Joshua Zeichner, MD, the director of cosmetic and clinical research in the dermatology department at Mount Sinai Hospital’s Department of Dermatology in New York City. Because the cold temperatures delivered by the device penetrate only the upper layers of fat below the skin, the procedure is best used to eliminate small areas of stubborn fat. CoolSculpting can't change a person's overall body composition.

“It's important to think of CoolSculpting as a fat reduction treatment rather than a weight reduction treatment,” Dr. Zeichner says. “It is not effective for people who have visceral fat, which is fat around the organs.” Visceral fat is linked to high cholesterol, insulin resistance, cardiovascular disease, and breast cancer.But CoolSculpting mainly targets subcutaneous fat, which tends to be located on the lower half of the body and is “pinchable.”

CoolSculpting may be a good option for people who want to reduce subcutaneous fat in a specific area, and for whom surgery might be too risky (for example, organ transplant recipients), says Dr. Matarasso. But it can't remove as much fat as surgical options like liposuction, and it won't remove excess skin that may develop after childbirth or significant weight loss. Excess skin requires surgical removal, Matarasso says.

What Are the Potential Side Effects of CoolSculpting?

CoolSculpting is generally a safe, low-risk procedure.Common side effects are usually mild, and may include pain or decreased sensation in the targeted area. Some people may feel faint, nauseated, or dizzy during the procedure, or may develop a rash, swelling, or other discoloration afterward. But these side effects typically resolve on their own in the weeks following the procedure, Zeichner says.

In some cases, the procedure may result in irregular divots or ripples in the skin, Matarasso says. But this isn’t a common side effect — one review suggested this happened in 0.14 percent of procedures.

CoolSculpting can be unpredictable, Matarasso adds, noting that the person undergoing the procedure may be disappointed if their results aren’t what they expected.

What Is Paradoxical Adipose Hyperplasia?

PAH, the side effect that Evangelista reported, is the best-known moderate-to-severe potential side effect of CoolSculpting, though research has not yet determined what causes it. It occurs when CoolSculpting triggers an increase, rather than a decrease, in fat cells in the targeted area. Over the course of several months following the CoolSculpting treatment, PAH causes new tissue to grow in the shape of the treated area. The new tissue is usually harder than normal fat, and may have an almost rubbery texture, Matarasso says. Blood flow to the affected area may also increase. In some cases, new fat growth can't be removed using liposuction, Matarasso says, and the patient must choose between having the new tissue surgically removed or leaving it in place.

“This is terrible, because they had someone who wanted a minimally invasive procedure,” he says, “and then they end up with a big scar.”

The amount of data available about the people who develop PAH is limited, Matarasso says. He adds that this is partly because the procedure is not always performed by doctors, who are required to report negative outcomes.

One clinical report suggested PAH may be underreported; the authors noted that the incidence rate of PAH at their practice was significantly higher (2 in 422, or 0.47 percent) than the incidence rate claimed by the CoolSculpting brand (1 in 20,000).

PAH may be slightly more common in males than in females, though the reason is unclear.

The study also noted that the incidence of PAH was 75 percent lower when technicians used newer-model CoolSculpting units, suggesting that the machines themselves may be a contributing factor to the risk of PAH.