Cryolipolysis: The Science Behind Freezing Fat

What is Cryolipolysis

Cryolipolysis, also known as “fat freezing”, is a noninvasive cosmetic procedure for fat reduction over a localized area of the body. The idea of fat reduction from freezing came from the observation that a child’s cheeks undergo temporarily loss of cheek fat (a phenomenon called cold-panniculitis) after sucking on an ice-popsicle.^[1] The first cryolipolysis machine was first introduced in 2007.^[2]  It is now used for body contouring and is an alternative to liposuction and surgical fat resection (commonly known as “tummy tuck”). An example of a cryolipolysis device is Coolsculpting^®.^[3]

How Does Cryolipolysis Work?

Cryolipolysis works by controlled cooling of the fat cells to near 4 degrees Celsius (approximately 39 degrees Fahrenheit), which destroys fat cells while reducing damage to surrounding skin, nerves, vessels, and muscles. This is because fat-containing body tissue is more vulnerable to cold-injury than the surrounding water-rich tissue.^[2] Cooling causes fat cells to undergo cell death, a processed called apoptosis. Apoptosis causes the release of inflammatory molecules (cytokines) around the treatment area; this is our body’s way of “cleaning up” dead debris. For mechanisms not entirely clear, it is hypothesized that over 2-4 months following treatment, our body naturally processes the dead cells, transporting them through the lymphatic system and eventually eliminating them. The end result is a reduction in the thickness of the fat layer.^[2] During this period when fat cells (adipocytes) gradually disappear, there is typically no increase in blood levels of fat (lipid) or change in liver enzymes.^[4,5] This makes researchers believe that cryolipolysis is a safe process of metabolism. In animal models, selective cooling causes inflammatory cells to surround and start digesting the injured fat cells within 24 hours after cold treatment. This inflammation subsides about 90 days after treatment, which correlates with the time course of gradual fat reduction after cryolipolysis.^[5]

What Conditions Does Cryolipolysis Treat? 

The ideal person to undergo cryolipolysis for fat reduction is someone who is already relatively fit but has stubborn fat bulges that do not easily go away with diet and exercise. Since cryolipolysis only treats a small area at a time, it is should not be used for general weight loss.

Coolscuplting^® is a device that is FDA-cleared for body contouring^[6] in individuals with a body mass index (BMI) of 30 or less for removing limited visible fat bulges located:

• under the chin (double chin),
• around bra straps
• abdomen
• flanks (love handles)
• underneath the buttocks (banana rolls).

Practitioners have also used cryolipolysis for other areas such as lumbar rolls (lower back), hip rolls, inner thighs, inner knees, arms, and ankles.

Some practitioners may also use cryolipolysis off-label for treatment of cellulite. However, well-designed clinical studies have not been done to prove its results and safety in cellulite treatment.^[7]

How is Cryolipolysis Done?

The cryolipolysis machine has a tissue-cooling applicator. One end of the applicator is attached to the treatment area on the skin while the other end is connected to a machine that generates energy for the cooling process. During treatment, the applicator is attached to the treatment area which undergoes controlled cooling. Cryolipolysis is supposed to be nonpainful and people should typically feel gentle suctioning and a cooling sensation over the treatment area. However, after the cooling treatment is complete, there is a massage step while the skin is rewarmed and this can feel painful and uncomfortable. Some practitioners may ask the patient to massage the treatment area for up to 4 months to enhance the fat reduction.^[8] 

People typically experience gradual fat loss for up to 6 months after treatment. Treatment can be repeated 2-4 months after the initial procedure if a greater fat reduction is desired.^[9] Since cryolipolysis is noninvasive, people can typically return to work and normal daily activity right after treatment. However, the result of fat reduction from cryolipolysis is more gradual and less dramatic compared to invasive procedures such as liposuction.

What Are the Potential Side Effects and Risks of Cryolipolysis? 

There may be temporary redness over the treatment area, which should typically resolve on its own within a few minutes to hours. Some people may get bruising and swelling which also clear on their own after a few weeks.

Some people, especially young women, who undergo abdominal cryolipolysis may experience delayed post-treatment pain, which resolves on its own within 3-11 days with long-term side effects.^[10] There have also been reports of people having increased fat growth after cryolipolysis.^[11] 

To date, despite the overall safety, the exact mechanisms of how the destroyed fat cells are metabolized and eliminated in our body after cryolipolysis remain unknown. Therefore, all potential side effects may not yet be known or reported.