CoolSculpting (Cryolipolysis) and Why I Withdrew DIY CoolSculpting

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The commercial CoolSculpting® device.

CoolSculpting® is a brand of cryolipolysis, a treatment that chills a fold of skin and fat to kill some of the fat cells underneath. It produces a real but small reduction in fat thickness in the treated area, typically a few millimeters two to three months after treatment[1][2][3]. The most important risk is paradoxical adipose hyperplasia (PAH), where the treated area grows more fat rather than less. When I first wrote this page, the quoted risk of PAH was about 1 in 20,000[4]. The best current estimate is about 1 in 450 patients, probably higher in men, and PAH usually needs liposuction or surgery to correct[5][6]. Earlier versions of this page also described a "DIY CoolSculpting" method using bags of ice water. I've withdrawn that advice, and I explain why below.

Summary

  • How much fat is lost? Typically a few millimeters of fat thickness in the treated area, or about 40ml of fat volume, measured two to three months after a single treatment[1][2]. It is a local, cosmetic change rather than a way to achieve Weight Loss.
  • What is the main risk? PAH in roughly 1 in 450 patients (0.22%)[5], with individual clinics reporting rates of 1-2% of patients, especially with older equipment[7][8]. Men appear to be at higher risk[5].
  • What else can go wrong? Temporary numbness, redness, swelling, and pain are common[3]. Rarer problems include persistent pain or altered sensation, motor nerve injury[9], frostbite[10], and reports of abdominal hernias[11].
  • How good is the evidence? Much of the efficacy research is small, short-term, and either funded by the manufacturer or carried out by researchers with financial ties to it.
  • What about DIY? I no longer recommend applying ice to reduce fat. See below.

What is CoolSculpting?

CoolSculpting is an FDA-cleared device[5]. An applicator, usually with vacuum suction, holds a fold of skin and fat against cold plates for a treatment cycle of roughly 35 to 60 minutes, depending on the applicator[2]. Fat-rich tissue crystallizes at higher temperatures than the surrounding water-rich tissue, so the fat cells can be damaged while the skin is spared[5]. The damaged fat cells die over the following weeks and are removed by the body's inflammatory response, mostly within about three months[5][3]. CoolSculpting was developed by ZELTIQ, which is now part of Allergan Aesthetics, an AbbVie company[5]. Other companies make cryolipolysis devices, and cheap imitation machines are widely sold online.

How Much Fat Is Lost?

The fat loss is real but modest.

  • In a study where 11 people had one flank (love handle) treated and the other flank left untreated as a control, skinfold thickness on the treated side fell from 45.6mm to 38.6mm after two months, while the untreated side did not change significantly. 3D imaging showed about 40ml more fat lost from the treated side[1]. A skinfold caliper measures a double layer of fat, so the change in the fat layer itself is roughly half the skinfold change.
  • An industry-sponsored study that treated each flank with a different applicator found an average reduction of 4.4mm in fat layer thickness, measured by ultrasound, 12 weeks after treatment[2].
  • A 2025 meta-analysis of 30 studies with 3,158 participants found that suprailiac skinfold thickness fell by an average of 5.2mm at 12 weeks, though the pooled change in overall subcutaneous fat thickness was not statistically significant[3]. The analysis compared measurements 12 weeks after treatment with each person's own baseline rather than with an untreated control, and the authors noted that follow-up was limited to about three months[3].

Much of this evidence comes from the manufacturer or from researchers with ties to it. For example, the ultrasound study above was sponsored by ZELTIQ[2], and the first author of the 2025 meta-analysis offers CoolSculpting in his clinics[3]. I've noted funding and conflicts of interest in the references where I could confirm them.

Risks and Side Effects

Paradoxical Adipose Hyperplasia (PAH)

PAH is a firm, well-defined increase in fat in the treated area that typically appears two to four months after treatment[5][8]. The first report, in 2014, put the risk at about 1 in 20,000 and noted that it appeared more common in men[4]. Since then, the estimates have risen steadily.

  • The rate reported by the manufacturer rose from 0.0051% in 2014 to 0.025% in 2018 and 0.033% (about 1 in 3,000) in 2021[5].
  • Individual clinics have reported much higher rates: 0.72% of treatments (about 1 in 138) in one Miami practice[6], and 4 of 398 patients (1%) in a French series[7].
  • A review of 2,114 patients at eight Canadian clinics found PAH in 2.0% of patients treated with older CoolSculpting units, falling to 0.11% after the clinics switched to newer units[8]. However, another large practice found little difference between applicator generations[5].
  • A 2025 systematic review and meta-analysis of 28 studies with 13,078 patients estimated that PAH affects 0.22% of patients (about 1 in 455), and 0.48% in the studies at lowest risk of bias[5]. The authors rated this evidence as low certainty. Only 4 of the 28 studies followed patients for 16 weeks or more, which is long enough to reliably detect PAH, so the true rate may well be higher[5].

In the studies that reported sex, PAH occurred in 1.39% of men and 0.14% of women. A formal statistical comparison was not significant because so few studies could be pooled, but the authors suggest male sex may be a risk factor[5]. PAH is benign, but it can be distressing, and because it develops slowly, many people assume the fat has simply come back[8]. A 2025 review found no reports of PAH resolving on its own[5]. Treatment is usually liposuction, typically after waiting several months, and occasionally abdominoplasty ("tummy tuck")[6].

An example of paradoxical adipose hyperplasia after cryolipolysis, showing a marked increase in fat in the treated area[4].
An MRI showing that the increase in fat is greatest at the edges of the treatment zone[4].

Other Side Effects and Complications

  • Common and usually temporary. In pooled data, about half of patients reported numbness, 45% redness, 31% swelling, and 29% pain[3].
  • Serious but rare. A systematic review of 53 papers listed severe or persistent pain, altered sensation (dysesthesia), skin darkening (hyperpigmentation), motor nerve injury, and PAH as the more serious complications[9].
  • Frostbite. Case reports include a full-thickness frostbite injury after treatment at a non-medical aesthetic clinic, which required hospitalization and several operations[10], and a smaller flank injury after treatment in a beauty salon[12].
  • Hernias. An analysis of the FDA's adverse event database (MAUDE) for 2015 to 2021 found 47 reports of abdominal hernias, all attributed to CoolSculpting devices. PAH made up 73% of the body contouring reports[11]. MAUDE reports cannot show how often a problem occurs or prove that the device caused it, but they do show these problems are being reported.
  • Blood fats and liver function. The 2025 meta-analysis found no significant changes in cholesterol, triglycerides, or liver enzymes[3].

If You're Considering CoolSculpting

If you're considering CoolSculpting, these points from the research are worth discussing with the clinic.

  • Expect a modest local change of a few millimeters, not weight loss[1][3].
  • Ask about PAH specifically, including how often the clinic has seen it, which generation of applicator they use[8], and how PAH would be treated.
  • Plan for follow-up of at least a year so that PAH is recognized rather than mistaken for fat returning[8].
  • Men should be aware that their risk of PAH appears to be higher[5].
  • Be wary of non-medical settings and unbranded devices, which feature in published frostbite reports[10][12].

CoolSculpting and Weight Maintenance

In earlier versions of this page, I wondered whether reducing the number of fat cells might make it easier to maintain weight loss, while admitting there was no evidence for the idea. The closest relevant evidence points the other way. In a randomized trial, 36 normal-weight women had small-volume abdominal liposuction. The fat under the skin did not grow back, but six months later the women who didn't exercise had a 10% increase in visceral fat (the fat around the abdominal organs), while an exercise program prevented this[13]. Cryolipolysis removes much less fat, and more gradually, so it may not trigger the same response. However, the idea that it helps with weight maintenance remains unsupported.

Why I Withdrew DIY CoolSculpting

Earlier versions of this page described a "DIY CoolSculpting" method of applying bags of ice water to the skin for one to three hours a day. This was based on my own experiment in 2012, after which I measured about a 2mm skinfold difference between the iced and un-iced sides of my abdomen. I've removed the instructions and equipment recommendations because I no longer think the possible benefit justifies the risks.

  • The evidence for benefit was weak. It was a single, unblinded self-experiment measured with skinfold calipers.
  • I focused on the wrong risk. I argued that ice water can't get cold enough to cause frostbite. That is broadly true, but prolonged cooling can cause other injuries at temperatures above freezing.
    • Nerve injury. Icing has caused peripheral nerve injuries in athletes, occasionally with disability lasting months. The risk is greater with thinner subcutaneous fat and longer cooling[14][15]. Lean runners icing for hours a day fit that profile.
    • Cold panniculitis. Cold can inflame the fat layer itself, causing painful nodules. This has been reported in an adult using a post-surgery cold therapy unit for one hour a night[16].
  • The PAH risk is unknown. One proposed cause of PAH is fat cells being injured but not killed, for example through poor contact with the applicator[5]. Home icing is far less controlled than a commercial device, and there is no data on whether it causes PAH.
  • Colder DIY methods are clearly dangerous. Using dry ice for DIY cryolipolysis has caused full-thickness wounds[17].

If you tried the DIY method from earlier versions of this page and have persistent numbness or weakness, painful lumps, or a firm area of fat that is growing rather than shrinking, please see a doctor.

Page History

I substantially rewrote this page in October 2026. Earlier versions were more enthusiastic about CoolSculpting, quoted an outdated PAH risk, and included the DIY method described above. I've also removed sections on device temperatures, massage after treatment, and thermogenesis. Older versions remain available in the page history.

References

  1. ↑ 1.0 1.1 1.2 1.3 Lilit Garibyan, William H. Sipprell, H. Ray Jalian, Fernanda H. Sakamoto, Mathew Avram, R. Rox Anderson, Three-dimensional volumetric quantification of fat loss following cryolipolysis, Lasers in Surgery and Medicine, volume 46, issue 2, 2014, pages 75–80, doi 10.1002/lsm.22207, PMID 24535759
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Suzanne L. Kilmer, Prototype CoolCup cryolipolysis applicator with over 40% reduced treatment time demonstrates equivalent safety and efficacy with greater patient preference, Lasers in Surgery and Medicine, volume 49, issue 1, 2017, pages 63–68, doi 10.1002/lsm.22550, PMID 27327898. Industry funded: sponsored by ZELTIQ Aesthetics; the author is on ZELTIQ's medical advisory board and receives research support from ZELTIQ and Allergan.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 R. Ravindran, D. Pizzol, M. Rahmati, S. Caminada, DK. Yon, JI. Shin, N. Veronese, P. Soysal, G. Fond, L. Boyer, JF. López-Gil, K. Kostev, J. Gawronska, L. Smith, Cryolipolysis and associated health outcomes, adverse events, and satisfaction: A systematic review and meta-analysis, Obesity Reviews, volume 26, issue 8, 2025, e13925, doi 10.1111/obr.13925, PMID 40211915. No funding; the first author provides CoolSculpting to patients in his clinics.
  4. ↑ 4.0 4.1 4.2 4.3 H. Ray Jalian, Mathew M. Avram, Lilit Garibyan, Martin C. Mihm, R. Rox Anderson, Paradoxical Adipose Hyperplasia After Cryolipolysis, JAMA Dermatology, volume 150, issue 3, 2014, pages 317–319, doi 10.1001/jamadermatol.2013.8071, PMID 24382640
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 AE. Mah, P. Razeghi, C. Li, S. Datta, BK. Tao, J. Ahmad, RE. Austin, Incidence of Paradoxical Adipose Hyperplasia After Cryolipolysis: A Systematic Review and Meta-Analysis, Aesthetic Surgery Journal Open Forum, volume 7, 2025, ojaf142, doi 10.1093/asjof/ojaf142, PMID 41322038. No funding; one author (J. Ahmad) is a consultant for Allergan Aesthetics.
  6. ↑ 6.0 6.1 6.2 ME. Kelly, J. Rodríguez-Feliz, C. Torres, E. Kelly, Treatment of Paradoxical Adipose Hyperplasia following Cryolipolysis: A Single-Center Experience, Plastic and Reconstructive Surgery, volume 142, issue 1, 2018, pages 17e–22e, doi 10.1097/PRS.0000000000004523, PMID 29952891
  7. ↑ 7.0 7.1 N. Stroumza, N. Gauthier, P. Senet, P. Moguelet, R. Nail Barthelemy, M. Atlan, Paradoxical Adipose Hypertrophy (PAH) After Cryolipolysis, Aesthetic Surgery Journal, volume 38, issue 4, 2018, pages 411–417, doi 10.1093/asj/sjx159, PMID 29145587
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 A. Nikolis, KM. Enright, A Multicenter Evaluation of Paradoxical Adipose Hyperplasia Following Cryolipolysis for Fat Reduction and Body Contouring: A Review of 8658 Cycles in 2114 Patients, Aesthetic Surgery Journal, volume 41, issue 8, 2021, pages 932-941, doi 10.1093/asj/sjaa310, PMID 33216910. No funding; the first author is a consultant speaker and research collaborator for Allergan.
  9. ↑ 9.0 9.1 B. Hedayati, M. Juhász, S. Chu, NA. Mesinkovska, Adverse Events Associated With Cryolipolysis: A Systematic Review of the Literature, Dermatologic Surgery, volume 46, supplement 1, 2020, pages S8–S13, doi 10.1097/DSS.0000000000002524, PMID 32976167
  10. ↑ 10.0 10.1 10.2 C. Benoit, A. Modarressi, Severe frostbite complication after cryolipolysis: A case report, JPRAS Open, volume 25, 2020, pages 46–51, doi 10.1016/j.jpra.2020.05.004, PMID 32637531
  11. ↑ 11.0 11.1 Y. Lim, A. Wulkan, M. Avram, FDA MAUDE database reported adverse events on noninvasive body contouring, cellulite treatment, and muscle stimulation from 2015 to 2021, Lasers in Surgery and Medicine, volume 55, issue 1, 2023, pages 146–151, doi 10.1002/lsm.23592. No outside funding; the authors reported no financial conflicts.
  12. ↑ 12.0 12.1 W.L. Choong, H.S. Wohlgemut, M.J. Hallam, Frostbite following cryolipolysis treatment in a beauty salon: a case study, Journal of Wound Care, volume 26, issue 4, 2017, pages 188–190, doi 10.12968/jowc.2017.26.4.188
  13. ↑ F. Benatti, M. Solis, G. Artioli, E. Montag, V. Painelli, F. Saito, L. Baptista, LA. Costa, R. Neves, M. Seelaender, E. Ferriolli, K. Pfrimer, F. Lima, H. Roschel, B. Gualano, A. Lancha Jr, Liposuction Induces a Compensatory Increase of Visceral Fat Which Is Effectively Counteracted by Physical Activity: A Randomized Trial, J Clin Endocrinol Metab, volume 97, issue 7, 2012, pages 2388–2395, doi 10.1210/jc.2012-1012, PMID 22539589. Publicly funded (FAPESP).
  14. ↑ FH. Bassett, JS. Kirkpatrick, DL. Engelhardt, TR. Malone, Cryotherapy-induced nerve injury, American Journal of Sports Medicine, volume 20, issue 5, 1992, pages 516–518, doi 10.1177/036354659202000505
  15. ↑ TR. Malone, DL. Engelhardt, JS. Kirkpatrick, FH. Bassett, Nerve Injury in Athletes Caused by Cryotherapy, Journal of Athletic Training, volume 27, issue 3, 1992, pages 235–237, PMID 16558167
  16. ↑ MM. Lipke, JE. Cutlan, AC. Smith, Cold Panniculitis: Delayed Onset in an Adult, Cutis, volume 95, issue 1, 2015, pages 21–24
  17. ↑ C.D. Leonard, S.A. Kahn, J.B. Summitt, Full-thickness wounds resulting from 'do-it-yourself' cryolipolysis: a case study, Journal of Wound Care, volume 25, issue Sup4, 2016, pages S30–S33, doi 10.12968/jowc.2016.25.Sup4.S30
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