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Surgery and Cosmetics

Cryolipolysis: The Cold War Against Fat

Nazanin Saedi, Anthony Petelin, Christopher Zachary

Thursday, July 15, 2010

With the rising demand for body contouring, non-invasive mechanisms for fat reduction have become increasing popular. Cryolipolysis is a novel technology using controlled cold exposure, which selectively reduces subcutaneous fat. The technology is based on the concept of "popsicle panniculitis", or cold-induced inflammation of adipose tissue and resulting fat loss. By controlling and modulating the cold exposure, it is possible to selectively damage adipocytes, while avoiding damage to the overlying epidermis and dermis. The decrease in fat thickness occurs gradually over the subsequent 3 months, and it is most pronounced in patients with limited, discrete fatty bulges.

Mechanism of Action

The exact mechanism of cryolipolysis remains unknown. Adipocytes appear to be more susceptible than skin cells to necrosis after exposure to cold. The initial reports of infants suffering from cold panniculitis and adults with equestrian panniculitis demonstrate a perivascular inflammatory infiltrate consisting of histiocytes and lymphocytes, developing approximately 24 hours after cold exposure. This inflammatory infiltrate subsequently progresses to a lobular panniculitis, with resolution over several weeks, and ultimately results in fat resorption without persistent tissue damage or scarring.1,2

The use of cryolipolysis for fat reduction shows similar histologic findings. Immediately after treatment, adipocytes are intact and there is no apparent fat damage. Within 3 days of treatment, there is evidence of adipocyte apoptosis with an influx of inflammatory cells.3 At approximately 14 days, the inflammation peaks and, between 14 and 30 days after treatment, lipid phagocytosis becomes apparent. The adipocytes become smaller and irregularly shaped as they are slowly digested by macrophages. After this period, the inflammatory response subsides and the volume of fat cells decreases, with apparent thickening or condensation of the interlobular septae occurring by 60 days. The inflammatory process declines further by day 90 post-treatment.

Clinical Use

Cryolipolysis studies conducted on Yucatan pigs demonstrated significant fat reduction using a prototype device, without any change in the serum lipid levels.4 The Zeltiq System (Zeltiq Aesthetics Inc, Pleasanton, CA) was developed subsequent to these animal studies, with similar predictable results. This device consists of a control console, with a treatment applicator attached by a cable. A thermal coupling gel sheet is placed on the area to be treated, and the applicator is then applied. The target tissue is drawn into the cup-shaped applicator with a moderate vacuum to position the tissue optimally between two cooling panels. A cooling intensity factor (CIF) is then selected by the treating clinician. The CIF is an index value representing the rate of heat flux into or out of tissue opposite the cooling device. The cold exposure treatment is generally 60 minutes per area. The energy extraction rate, or cooling, is controlled by sensors that monitor the heat flux out of the treated areas and is modulated by thermoelectric cooling cells. Following completion of the treatment cycle, the vacuum is released and the device is transferred to the next area to be treated.

Given that the applicator is only able to chill a relatively small area at any one time, multiple applications may be necessary to effectively expose the entire area to cryolipolysis. For instance, it might take two or three applications per session to treat the abdomen, and four applications to treat both "love handles". Review at 2-3 months indicates good or very good fat reduction in about 70% of cases when appropriate patient selection is made (Figures 1 and 2). Ultrasound examination both pre- and post-treatment indicates that approximately 100% of patients respond. However, in our opinion, it is the patient's perception of improvement that is the most important consideration. Thus, patient expectations must be reasonable. It is important to note that the Zeltiq device is presently FDA-indicated for skin cooling and surface anesthesia, and that use of the Zeltiq device for cryolipolysis is currently off-label.

Figure 1. Prior to treatment. (Photograph courtesy of Christopher Zachary, FRCP)


Figure 2. 3 months post-treatment. (Photograph courtesy of Christopher Zachary, FRCP)

Safety Profile

The known risks of the procedure include relatively modest discomfort during the procedure, temporary erythema of the skin, transient bruising, and a dysaesthesia at the treatment site, which generally disappears within a few weeks. Coleman et al. reported that there are no long-term sensory effects and, to date, there have been no reports of scarring, ulceration, or alterations in blood lipid or liver function profiles.5,6 However, we have noted that two patients have reported "severe pain" following this treatment: one case in Southern California, and the other in Ottawa. These were both self-limiting, but lasted for several weeks. In at least one of these cases, the patient had an excellent result.


Cryolipolysis is a novel procedure, which uses controlled cold exposure to produce non-invasive, essentially painless and predictable adipocyte loss. In animal and human clinical studies, cryolipolysis has been shown to result in significant improvement in the clinical appearance of localized fatty deposits. The current data support the concept that cryolipolysis is most effective for localized, discrete fatty bulges. The patients who desire large-scale fat removal should rely on weight reduction with exercise and diet, although localized fat loss may still be achieved in some of these cases with cryolipolysis. The treatment is particularly appealing given that it is not associated with any downtime, and it does not require local or regional anesthesia. Overall, cryolipolysis appears to be a promising new technology for safe, effective, and non-invasive treatment of fat.


  1. Epstein EH Jr, Oren ME. Popsicle panniculitis. N Engl J Med 1970;282:966-967.
  2. Nelson AA, Wasserman D, Avram MM. Cryolipolysis for reduction of excess adipose tissue. Semin Cutan Med Surg 2009;28:244-249.
  3. Avram MM, Harry RS. Cryolipolysis for subcutaneous fat layer reduction. Lasers Surg Med 2009;41:703-708.
  4. Zelickson B, Egbert BM, Preciado J, et al. Cryolipolysis for noninvasive fat cell destruction: initial results from a pig model. Dermatol Surg 2009;35:1462-1470.
  5. Klein KB, Zelickson B, Riopelle JG, et al. Non-invasive cryolipolysis for subcutaneous fat reduction does not affect serum lipid levels or liver function tests. Lasers Surg Med 2009;41:785-790.
  6. Coleman SR, Sachdeva K, Egbert BM, Preciado J, Allison J. Clinical efficacy of non-invasive cryolipolysis and its effects on peripheral nerves. Aesthetic Plast Surg 2009;33:482-488.