Non-invasive Fat Removal and Tissue Tightening: What’s the Truth?

Mathew M. Avram, MD, JD

Non-invasive Fat Removal

This is a technique with limited, but real efficacy. It is important that Dermatologists critically assess these technologies in this emerging field. There are many different technologies for fat removal, the first of which is Focused Ultra Sound, known commercially as “Ultra Shape”.  This is mechanical, non-thermal energy. It is currently not FDA approved.  The initial study looked at 30 patients treated at 3 monthly sessions. The researchers did bilateral treatments, with no control, of thighs, abdomen, and flanks and achieved a circumference reduction of 2-3 cms.  LFTs, lipids, & liver ultrasound showed no adverse systemic effects and there were similar findings in a subsequent study.  The problem that clinicians face is that there was no untreated control so it is difficult to ascertain the true degree of efficacy.  Circumference, when subject to mathematical analysis, is an inherently imprecise measure of improvement.  MRI could provide a more objective improvement; however, it was performed in this study.

A subsequent study in Hong Kong using this device treated 51 subjects, with 3 monthly treatments. They didn’t see any significant change in ultrasound, circumference or caliper measurements and it resulted in poor patient satisfaction.

High-Intensity Focused Ultrasound is commercially known as Lipo Sonix, was recently FDA-cleared. This features rapid heating of adipocytes producing coagulative necrosis and cell death in adipose tissue.  There is a published retrospective study that looked at 85 patients with1 treatment session. On average a 4.6 cm decrease in waist circumference was seen after 3 months and lipids, LFTs, and CBC were within normal limits. Temporary adverse effects in 11.8% of patients (4-12 weeks) included prolonged tenderness, ecchymosis, nodules, edema, and procedural pain in one patient that required discontinuing the procedure. Unfortunately, this was not an ideal study because it was retrospective and diet was not controlled. Dr Avram felt that this, in fact, undermines the findings of the study.

In a recent poster presentation, diet was controlled and there was a statistically significant circumference improvement at 12 weeks in treated patients versus sham patients. Yet, it was unclear how circumference measurement was validated.

Adverse events were more common than in the published study and included procedural pain in 90% of patients, post-treatment pain in 57%, bruising in 66%, and swelling in 9%.

Monopolar radiofrequency has been shown to produce lipoatrophy in some patients and is still awaiting clinical studies. Bipolar radiofrequency which is combined with infrared light and vacuum massage, is FDA approved; however, its efficacy is yet to be determined.

Low level light therapy (LLLT), which is, FDA-cleared, is a multiple head low-level diode laser at 635 nm. An LLLT study (blinded bi-lateral treatments) looked at 59 patients who received three treatments per week for 2 weeks some improvement was reported however, at a minimum, further study is needed.  There were no data of efficacy more than 2 weeks out. There were no data on ultrasound or other non-invasive evidence of decreased fat layer and no histology.

Cryolipolysis is a technique that was developed at Massachusetts General Hospital and is FDA-approved for non-invasive fat removal.

Cryolipolysis is the non-invasive cooling of fat to selectively cause fat cell death without damage to surrounding tissue types. It is based on the concept of the clinical phenomenon of “popsicle panniculitis”.  The mechanism of action involves the selective crystallization of lipids in fat cells at temperatures above freezing. This results in apoptotic fat cell death followed by slow dissolution of cells and gradual release of lipids; therefore, causing an inflammatory process resulting in fat layer reduction over 2-3 months. After the animal studies, there was a human study where 32 subjects in the “love handle” group were analyzed. One side was treated and there was a contra-lateral side untreated control. The parameters ranged from CIF 33 (-64 mW/cm2) for 60 minutes to CIF 42 (-72 mW/cm2) for 45 minute. The researchers evaluated efficacy 4 months post-treatment utilizing visual assessment as primary a endpoint, as well as ultrasound and histology. Ultrasound showed a   22.7% decrease in fat layer thickness. Post-procedure side effects included redness that lasted for a few minutes to a few hours, bruising and temporary dulling of sensation in treated area. There were no changes in pigmentation and type VI skin types have been successfully treated.  No laboratory abnormalities were detected. A  rare side effect (1 in 1,500) is the report of significant pain lasting about 2 weeks and resolves without sequelae. The mechanism for this side effect is unknown.

Treated and Control Side

In conclusion, the data regarding cryolipolysis (Zeltiq) indicates clear, but limited non-invasive fat removal. It not a replacement for liposuction and is not a weight loss device. It is best suited for local fat removal resistant to exercise in relatively fit patients. The best areas to treat are the love handles and lower abdomen. It is important that clinicians recognize that patient selection is crucial.

We can see that non-invasive fat removal is here. It cannot be compared to liposuction. There are several different technologies presently available. Proper patient selection is important as some devices work, and others do not.

Tissue Tightening

Many different technologies exist for tissue tightening.  They all attempt to tighten skin laxity by the deposition of heat.

The temperature-related effects will differ depending on the amount of heating that one chooses to perform:

42-52 ºC reversible injury, heat shock
> ~52 ºC cell apoptosis, necrosis
> ~68 ºC type I collagen denaturation
> ~100 ºC vaporization

The mechanism of action  is tissue contraction; therefore, each device produces heating of the dermis in order to cause significant shortening of collagen structures.  The devices also want to achieve a secondary wound healing response with collagen deposition. This has been demonstrated using monopolar radiofrequency (Thermage technology) using animal histology.

Tissue Tightening Technologies

The good news is that these technologies can achieve a certain degree of tissue tightening and they are continuing to improve and, for the most part, they are rather safe. The bad news is that the results can be unpredictable and in many cases are not seen. Each patient has to be looked at individually and they must realize that the results can take months before they are actually manifested. These treatments can often be painful and quite expensive and many times patients may require multiple treatments. It is important that physicians counsel patients and give them a proper sense of potential results.

Ablative Fractional Resurfacing

Ablative fractional resurfacing can produce some modest tissue tightening.  However it is very important to resist the temptation to be aggressive in order to maximize the clinical benefit.  Hypertrophic scarring of the neck has been reported with ablative fractional resurfacing.  (Avram MM, Tope WD, Yu T, Szachowicz E, Nelson JS. Hypertrophic scarring of the neck following ablative fractional carbon dioxide laserresurfacing. Lasers Surg Med. 2009 Mar;41(3):185-8.)


There are monoploar, bipolar and fractional bipolar radiofrequency devices. The mechanism of action of monopolar radiofrequency devices is that the current runs through the dermis but does not conduct well in the fat however it conducts along the septae in the fat causing heating of the septae and surrounding fatty tissue. Monopolar radiofrequency devices that are combined with a superficial radial cooling component (Thermage device) allows the user to change cooling and heating parameters to deliver heat to the deeper tissue in a given targeted area while protecting the epidermis with the cooling system. There is also no patient recovery time. It often takes up to 3-6 months to see the results.

Biopolar radiofrequency consists of two electrodes.  The heat runs between them and many of these devices are coupled with a suction device to maximize the tissue between the electrodes allowing clinicians to achieve deeper penetration. It may provide a mild benefit for tissue tightening.

Fractional bipolar radiofrequency utilizes a fractional pattern of bipolar RF heating that is delivered by a micro-needle electrode array directly into the deep dermis .It provides real time dermal temperature monitoring.  The treatment is painful and requires significant anesthesia.  However, its efficacy is yet to be determined.

Focused ultrasound (US) allows for deep, non-invasive treatment at any tissue depth. US can treat far below the dermis.  Treatments are guided by real time imaging.  The key to success and avoiding complications is to target carefully using imaging to guide the treatment of the skin and SMAS.  It is important to remember that one should avoid targeting any arteries or nerves.  It has great potential for not only targeting tissue for aesthetic purposes but for other medical therapies.

Skin Imaging Slide

Skin Imaging

Issues around US include clinical questions regarding pattern, depth, density and the number of necessary treatments. US looks like a promising technology; yet, its efficacy still requires more proven results.

Its important to remember that there are limits to tissue tightening technologies. It is important to discuss these issues with patients and consider that the current treatment paradigm may need to be approached in a different manner. Perhaps dermatologists need to consider restoring elasticity, rather than tightening. We do know that tissue tightening can improve non-invasive skin elasticity, the results are unpredictable, this should not be looked at like a face-lift and patient education and communication is key its the success.