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Cryolipolysis is a medical treatment used to destroy fat cells. Its principle relies on controlled cooling to near 4 Celsius for the non-invasive localized reduction of fat deposits in order to reshape body contours. The exposure to cooling is set so that it causes cell death of subcutaneous fat tissue without apparent damage to the overlying skin. The procedure is billed as a nonsurgical alternative to liposuction. "Cryolipolysis" is a portmanteau of "cryogenic" and "lipolysis." Generically the process can also be known as "fat freezing". Specific treatments are using medical devices called CoolSculpting made by Zeltiq Aesthetics, Inc. In Europe cryolipolysis machines are used in aesthetic clinics and spas.
Method of action and animal studies
Lipolysis procedures attempt to "dissolve" fat cells by nonsurgical means. A number of methods have been attempted, including the use of laser, ultrasound, and Radio frequency current. Popsicle panniculitis is a dermatologic condition that shows that exposure to low temperatures can selectively damage subcutaneous fat while leaving skin intact. Based on the premise that fat cells are more easily damaged by cooling than skin cells, Cryolipolysis was developed to apply low temperatures to tissue via thermal conduction. In order to avoid frostbite, a specific temperature level and exposure is determined. Physicians Dieter Manstein and R. Rox Anderson at The Wellman Center at Massachusetts General Hospital originated the concept, explored it in a number of experiments on pigs, and reported their data in 2008. While the process is not fully understood, it appears that fatty tissue that is cooled below body temperature but above freezing undergoes localized cell death followed by a local inflammatory response, a local panniculitis, that gradually over the course of several months results in a reduction of the fatty tissue layer. When exposed to extreme cold, the body's usual response is to restrict circulation to keep the core of the body at the correct temperature. Cryolipolysis makes use of a powerful vacuum which adds to the inflammatory response by drawing blood up to the surface layers of the skin.
Experience in humans
The first human study appeared in 2009 when Coleman et al. reported results after cryolipolysis had been applied to love handles in a single session to ten patients, each patient being their own control. A session takes less than an hour and does not require anesthesia. With a single treatment subjects had a 20% reduction after two months and 25% reduction at six months in the fat layer as assessed by ultrasound. The lipolytic effect of treatment takes place within about two to four months. It appears primarily applicable to limited discrete fat bulges. With the small number of patients treated, clinical data remain scarce, thus it is not known how long the treatment effect will last, or when and if later treatments would be necessary to maintain the result.
Side effect data are based on a limited experience. Transient local redness, bruising and numbness of the skin are common side effects of the treatment and are expected to subside. Typically sensory deficits will subside within a month. The effect on peripheral nerves was investigated and failed to show permanent detrimental results. No serious long-lasting side effects were encountered during follow-up time of six months.
Typical cost per treatment area ranges from $750 to $1500 depending on the size of the applicator and the area being treated. 
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- Ingargiola MJ, Motakef S, Chung MT, Vasconez HC, Sasaki GH (June 2015). "Cryolipolysis for fat reduction and body contouring: safety and efficacy of current treatment paradigms.". Plast Reconstr Surg. 135 (6): 1581–90. doi:10.1097/PRS.0000000000001236. PMC 4444424. PMID 26017594.
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- Manstein, D; Laubach, H; Watanabe, K; Farinelli, W et al. (2008). "Selective cryolysis: A novel method of non-invasive fat removal". Lasers in Surgery and Medicine 40 (9): 595–604. doi:10.1002/lsm.20719. PMID 18951424.
- Zelickson, B; Egbert, BM; Preciado, J; Allison, J et al. (2009). "Cryolipolysis for noninvasive fat cell destruction: Initial results from a pig model". Dermatologic Surgery 35 (10): 1462–70. doi:10.1111/j.1524-4725.2009.01259.x. PMID 19614940.
- Coleman, SR; Sachdeva, K; Egbert, BM; Preciado, J et al. (2009). "Clinical efficacy of noninvasive cryolipolysis and its effects on peripheral nerves" (PDF). Aesthetic Plastic Surgery 33 (4): 482–8. doi:10.1007/s00266-008-9286-8. PMID 19296153.
- Nelson, AA; Wasserman, D; Avram, MM (2009). "Cryolipolysis for reduction of excess adipose tissue". Seminars in Cutaneous Medicine and Surgery 28 (4): 244–9. doi:10.1016/j.sder.2009.11.004. PMID 20123423.