In today’s society there is a ubiquitous pressure to lose weight, reduce fat, and rejuvenate the skin that stems not only from images of idealized bodies in the media but also from our growing knowledge of the detrimental effects of obesity. Along with diet and exercise, it has become popular to use noninvasive devices to attain these goals by means of body contouring—the optimization of the definition, smoothness, and shape of the human physique.1 In fact, body contouring currently is the fastest-growing area of cosmetic dermatology.2
Previously, body contouring primarily involved invasive procedures (eg, liposuction) that are associated with various adverse effects, financial costs, and lengthy downtime.3 More recently, a growing demand for safer and less painful procedures for adipose tissue reduction and skin tightening have led to the development of several novel modalities for noninvasive body contouring. Although the results achieved using these new technologies may be less dramatic than invasive techniques and are not immediate, they do not carry the risks and adverse effects that are associated with surgical procedures and therefore are increasingly requested by cosmetic patients.4,5 New noninvasive techniques primarily target the physical properties of fat, resulting in an efflux of triglycerides from fat cells, causing either reduced size, necrosis, or apoptosis of adipocytes.3,6 Of these modalities, cold-induced adipocyte apoptosis has been commercially available the longest and has been the most researched; however, other noninvasive body contouring techniques have been increasingly explored by researchers since the first reports of human adipose tissue explants exhibiting features of apoptosis after heat injury became available.7,8
There currently are 4 leading modalities used for noninvasive body contouring: cryolipolysis, radiofrequency (RF), high-intensity focused ultrasound (HIFU), and laser therapy (Table). Although no procedure has yet been accepted as the gold standard, investigators are working to determine which technique is the most effective.9 In this article, we provide an overview of these techniques to help dermatologists choose appropriate modalities for their cosmetic patients.
Cryolipolysis is unique in that it employs the principle that lipid-rich adipocytes are more susceptible to freezing than surrounding water-rich cells, allowing selective apoptosis while preserving the adjacent structures. As macrophages digest the apoptotic adipocytes, patients experience a decrease in subcutaneous fat volume over the subsequent 2 to 3 months.10-13 Cryolipolysis has been gaining popularity since 2010, when it was first approved by the US Food and Drug Administration (FDA) for fat reduction in the flank areas; it was later approved for the abdomen in 2012, thighs in 2014, and submental area in 2015.14 Most recently, cryolipolysis was approved for fat reduction in the arms, back, and buttocks in 2016.
The most popular cryolipolysis device applies suction to the treatment area and vacuums the tissue between 2 cooling panels for 30 to 60 minutes.9 Clinical studies investigating the safety and efficacy of cryolipolysis have reported a high degree of patient satisfaction with the procedure and only minimal side effects.4,6,15,16 Common complications of cryolipolysis include erythema, swelling, and sensitivity at the treatment site followed by a lesser incidence of pain, tingling, and bruising, all of which generally resolve within a few weeks of treatment.6 With the removal of adipocytes, there has been concern regarding elevations in blood lipid levels and liver enzymes; however, these laboratory values have been reported to remain within normal limits during and after cryolipolysis.17,18 Of note, patients should be advised of the risk of paradoxical adipose hyperplasia, a rare side effect of cryolipolysis in which a large, demarcated, tender fat mass develops at the treatment site 2 to 3 months after treatment, with an estimated incidence of 1 in 20,000.19 However, the incidence of paradoxical adipose hyperplasia may be underestimated, as a single practice reported an incidence of 0.47% in 422 cryolipolysis treatments.20 This complication has not been associated with any of the heat-induced fat reduction modalities.
Cryolipolysis has been found to be safe for all skin types with no reported pigmentary changes.16 It should not be performed in patients with cold-induced conditions (eg, cryoglobulinemia, cold urticaria) or in those with severe varicose veins or atopic dermatitis.21,22 Patients benefitting most from this procedure are those who require only small or moderate amounts of adipose tissue and cellulite removal with separate fat bulges.12,17 Interestingly, cryolipolysis also has been used off label to treat pseudogynecomastia in male patients.23