Abdominal obesity, characterized by the accumulation of excess fat in the abdominal region, is a significant risk factor for cardiovascular diseases. It contributes to the development of major classical risk factors, including dyslipidemia and insulin resistance, eventually leading to atherosclerosis. As such, interventions targeting abdominal fat reduction have gained considerable attention.
The Role of Subcutaneous Adipose Tissue
Subcutaneous adipose tissue acts as a buffer for dietary fatty acids (FAs), storing and releasing them under the influence of various factors. The fatty acid composition of adipose tissue reflects dietary intake of FAs over the previous 6 to 9 months. The ratio of consumed FAs, especially the content of mono- and polyunsaturated FAs to saturated FAs in the diet, is crucial in the development of atherosclerosis.
Non-Invasive Techniques for Adipose Tissue Reduction
In recent years, aesthetic medicine treatments have become increasingly popular. Interventions like liposuction, injection lipolysis, ultrasound, and radiofrequency treatments aim to reduce adipose tissue. However, these procedures may carry a risk of metabolic disorders with effects that are difficult to assess. Adipose tissue lysis occurs during these procedures due to damage to adipocyte cell membranes, potentially dispersing triglycerides into the interstitial fluid.
Ultrasound for Body Sculpting
Ultrasound used for body sculpting falls into two categories: relatively low-intensity/low-frequency nonthermal ultrasound and high-intensity focused ultrasound (HIFU). Ultrasound can lyse adipocytes through mechanical and thermal mechanisms. Nonthermal ultrasound uses a low frequency to increase the likelihood of cavitation while generating little heat through absorption mechanisms. At lower frequencies, ultrasound can easily cause cavitation, creating holes (cavities) when the ultrasound wave has sufficient negative pressure to overcome the adhesion of the medium molecules to each other, causing cell death. Low-intensity nonthermal ultrasound is approved for circumference reduction of the waist, hips, and thighs. The mechanical energy may also be absorbed by the tissues and converted into heat, which can cause changes such as improved microcirculation, accelerated metabolism, activation of enzymatic reactions, increased elasticity of collagen fibers, and increased permeability of cell membranes. HIFU delivers focused, high-intensity ultrasonic energy to deep subcutaneous tissue, producing heat capable of ablating adipose tissue and thermally modifying collagen.
Radiofrequency Treatments
Radiofrequency is another non-invasive method that generates heat in different tissues by transforming energy through three basic mechanisms from an electromagnetic field: (i) orientation of electric dipoles, (ii) polarization of atoms and molecules, and (iii) displacement of conduction electrons and ions in the tissue. Radiofrequency primarily works through skin tightening rather than destruction of adipose tissues, making it better suited for patients with cellulite than for reduction in waist circumference.
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With monopolar radiofrequency devices, energy passes from a single electrode into the skin and subcutaneous tissues and is directed to a return pad in another area of the body. With multipolar radiofrequency, two or more electrodes within the same handpiece are positioned at different points on the skin so that the waves pass between them to create heating. This latter method directs the trajectory of the current but not the depth. The temperature of tissues increases to 45-55 °C. A large portion of the heat generated by radiofrequency electromagnetic waves is absorbed by subcutaneous adipose tissue, muscles, body fluids, and parenchymal organs. Increased temperature causes vasodilatation and enhancement of tissue metabolism, as well as the destruction of the cross-links between collagen fibers. Skin and subcutaneous tissues are heated to the same extent. Radiofrequency emitting devices generally use skin cooling to protect the epidermis from thermal damage. RF waves can be delivered in a continuous or pulse mode. In pulse mode therapy, the temperature increase is lower, but deeper penetration is achieved.
Evaluating the Effects of Lipocavitation and Thermolipolysis
Given the limited reports on the effects of non-invasive techniques for adipose tissue reduction on metabolic parameters, a study was conducted to evaluate the early and long-term metabolic effects of lipocavitation and/or thermolipolysis on abdominal fat reduction.
Study Design and Methods
The study population comprised 60 women with low risk of cardiovascular diseases but with excessive accumulation of adipose tissue in the abdominal region. Subjects were randomly allocated into one of 3 subgroups: ultrasound (U group), radiofrequency (RF group), or combined radiofrequency and ultrasound (RF/U group). Each subgroup received 10 treatments for the abdominal region, provided three times a week. Each treatment involved 20 minutes of massage with a dedicated applicator head on a rectangular 20 cm × 10 cm area of the abdominal region. Ultrasound treatments were performed using an applicator head with a 38.47 cm2 spot area, generating ultrasound with 1 MHz frequency and 1.4 W/cm2 intensity. Radiofrequency treatments were performed using an applicator with a 20 cm2 spot area generating electromagnetic waves with 1 MHz frequency and 5 W/cm2 intensity. In the RF/U group, massage with a radiofrequency applicator head (20 min) was followed by a massage with a head generating ultrasound (20 min). During the study, participants continued with their usual diet and physical activity.
Anthropometric parameters, including body height, body weight, waist and hip circumference, abdominal fat content, visceral fat content, and blood pressure, were measured. Body weight and height were measured with a certified device. Waist and hip circumferences were measured with a medical tape measure, and the content of abdominal fat and visceral fat was determined by bioimpedance analysis. The measured parameters were used to calculate the body mass index (BMI) and the waist-to-hip ratio (WHR).
Patients from all study subgroups were tested for white blood cell (WBC) count in peripheral blood and levels of glucose, insulin, C-reactive protein (CRP), total cholesterol (TC), LDL cholesterol, HDL cholesterol, and triglycerides (TG) in fasting venous blood plasma. Measured glucose and insulin levels (fasting) were used to calculate two insulin resistance indices, HOMA and QUICKI. All parameters were measured again after 10 treatments and 6 months after the last treatment. The determination of WBC, CRP, and the full lipid profile was also repeated 4 hours after the end of the first treatment. The plasma level of selected free fatty acids (FFAs) in fasting blood was also analyzed.
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Key Findings
The series of 10 treatments significantly reduced body weight, BMI, and waist circumference, and the effects persisted for 6 months after treatments. The performed treatments had no effect on the other analyzed parameters. The direct effect of the first treatment assessed 4 hours after the procedure showed an increase in inflammatory parameters (increased WBC count) but did not influence the level of lipids.
All treatments resulted in a reduction in body weight and BMI after 10 treatments, but the long-term effect evaluated 6 months after the last treatment was only found in the RF subgroup. None of the methods used alone resulted in short- and/or long-term hip circumference reduction. Short-term reduction in waist circumference was found for the RF and RF/U interventions, but not for U. Long-term reduction in waist circumference assessed 6 months after treatment was only achieved for the RF intervention.
Blood tests measuring the level of FAs showed no direct effect of the treatments on the early and short-term concentrations of the analyzed FAs, regardless of the treatment applied. RF and U treatments, but not RF/U, had a significant long-term effect on the levels of some FAs measured 6 months after the completion of treatments.
A series of 10 treatments to reduce abdominal adipose tissue using ultrasound, radiofrequency, or both methods resulted in a cosmetic effect reflected in weight loss and BMI reduction.
Ultrasonic Cavitation: A Closer Look
Ultrasonic cavitation is a non-invasive fat reduction technique that uses ultrasonic waves to break down fat cells without surgery. It is a popular alternative to traditional liposuction due to its lower risk and shorter recovery time. Patients can typically resume daily activities immediately after the session, making it a convenient option for busy individuals. The technology targets localized fat deposits effectively, including abdominal fat, thighs, and arms.
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How Ultrasonic Cavitation Works
The device uses ultrasonic waves to target specific areas, penetrating deep into the layers of fat. These waves vibrate at high speeds, causing adipocytes in adipose tissue to convert into liquid. A trained technician applies a special gel to the target area of adipose tissue and moves the applicator head over the area in a circular motion.
The liver plays a key role in processing the broken-down fat cells. Ultrasound fat reduction targets adipose tissue, helping reduce body fat percentage and improving overall health. Reducing fat can lower the risk of cardiovascular diseases and can lower the BMI.
Benefits of Ultrasonic Cavitation
- Non-invasive: No surgery is required.
- No downtime: People can resume their normal activities immediately after treatment.
- Targeted treatment: Patients can choose which parts of their body to treat.
- Cost-effective: Generally cheaper than surgical options like liposuction.
Limitations of Ultrasonic Cavitation
- Multiple sessions: Patients usually need multiple sessions to see results.
- Individual variability: It might not work for everyone, and some people may experience only minor changes in fat reduction.
- Potential side effects: Some patients report mild redness or swelling in the treated area; in rare cases, individuals might experience bruising or discomfort.
Ultrasound vs. Radiofrequency
Ultrasound and radiofrequency (RF) technologies reduce fat differently. Ultrasound uses high-frequency sound waves to create an ultrasound field, generating mechanical vibrations that disrupt fat cells. Radiofrequency employs electromagnetic waves to heat fat tissues, causing the fat cells to shrink and die.
Ultrasound technology is known for its precision, targeting only fat cells without affecting surrounding tissues like skin and muscles. RF technology heats a broader area, which can sometimes affect nearby tissues. Ultrasound is ideal for small, specific areas where precision is crucial, while RF might be better for larger areas needing both fat reduction and skin tightening.
What to Expect During and After Treatment
During an ultrasonic cavitation session, patients often feel warmth on their skin as the device emits sound waves that penetrate to target fat cells. Visible changes are not immediate; it typically takes a few weeks for noticeable changes to appear.
Staying hydrated is crucial after an ultrasonic cavitation session, as drinking plenty of water helps the body flush out the released triglycerides and other waste products. Patients should avoid alcohol and caffeine for at least 48 hours after the session. Most people see the full benefits of ultrasound fat reduction within 6 to 12 weeks.
Low-Intensity Ultrasound for Body Fat Reduction
Nonfocused low-intensity ultrasound is generally believed to be less efficacious than High-Intensity Focused Ultrasound (HIFU) at body fat reduction. However, this technology has already been widely used clinically for body contouring purposes.
Study on Low-Intensity Ultrasound
A study aimed to evaluate the efficacy and safety of this new technology by applying 1 MHz nonfocused ultrasound at 3 W/cm2 to the outer-thigh region of rat models. Ultrasonography measurement demonstrated an average reduction of 0.5 mm of subcutaneous fat thickness that persisted for at least three days after treatment. Biochemical analysis quantified a significant increase in lipid levels, specifically triglyceride, high-density lipoprotein, and total cholesterol. These two findings of subcutaneous fat reduction and plasma lipid increase showed a positive correlation. No evidence of adverse events or complications was observed after the treatment.
This study validated nonfocused low-intensity ultrasound as an effective and safe method for body fat reduction, especially with repetitive treatment. However, the concurrent increase in plasma lipid level will require further investigation to determine this technology's long-term impact, if any, on health.
Materials and Methods
Three-month-old male Sprague-Dawley (SD) rats (n = 11, weight: 396.4 ± 28.0 g) were randomly recruited. During housing, the rats received a normal diet without drugs that are known to induce lipolysis in animal model. General anesthesia was given to the rat subjects using 1 mL of Chloride Hydrate injected into the abdominal region with a 30-gauge needle syringe. Hair on the outer-thigh region was removed for better ultrasound transmission coupling. A commercial ultrasound device was used to treat the outer-thigh, generating continuous ultrasound wave with frequency of 1 MHz and intensity of 3.2 W/cm2.
Results
The effect of treatment yielded inconsistent results, ranging from 0.2 to 0.9 mm reduction in the fat layer. There was a statically significant reduction (p < 0.01) in the fat layer thickness between the pre-treatment and posttreatment groups, indicating that the intervention with low-intensity nonfocused ultrasound caused reduction in adipocyte thickness by inducing lipolysis.
Blood TG level increased by 0.42 ± 0.10 mmol/L, HDL increased by 0.53 ± 0.17 mmol/L, and total cholesterol increased by 0.50 ± 0.27 mmol/L after treatment. There were significant increases (p < 0.01) in all three blood lipid levels after treatment.
Statistical analysis showed a statically significant association (p < 0.05) between the increased lipid levels and the reduced fat layer thickness; however, these two parameters had poor linear correlation, with a maximal correlation coefficient of less than 0.6.
Discussion
The ultrasound settings used in this research experiment (1 MHz ultrasound at 3.2 W/cm2) mimicked those of therapeutic ultrasound devices claiming to be effective in body contouring. After a 30-minute treatment, the 11 rat subjects experienced an average fat layer reduction of 0.05 ± 0.02 cm (15.2% of the original thickness) in the outer-thigh region. This reduction was further maintained for at least 3 days posttreatment, indicating that low-intensity ultrasound may have a significant and durable effect on body fat reduction.
The biochemical analysis of plasma lipid changes provided further evidence supporting the treatment efficacy of low-intensity ultrasound in subcutaneous fat reduction. The three blood parameters, TG, HDL, and TC, all increased significantly after the ultrasound treatment, supporting the hypothesis that low-intensity ultrasound induced sonoporation in adipocytes to cause release of their lipid content into the microcirculation.
Non-Invasive Body Contouring: What to Consider
Body contouring, also known as body sculpting, refers to changing the shape of an area on your body and is used to describe a variety of effects such as:
- Changing the circumference of an area on your body like your waist or thighs.
- Changing your body’s silhouette by reducing small areas of fat.
- Improving tone and firmness of certain muscles.
- Improving the appearance of cellulite.
Non-invasive body contouring describes non-surgical procedures that do not remove any tissue (fat or skin) from the body. It is different from a surgical body contouring procedure, like tummy-tuck surgery, which cuts out excess skin, or liposuction, which uses a narrow vacuum-type device to pull fat out through a small incision. Non-invasive body contouring does not treat obesity or improve your health. It will not result in weight loss or contribute to the health benefits associated with weight loss.
Technologies Used in Non-Invasive Body Contouring
- Cold (Cryolipolysis or Fat Freezing): Uses cold temperatures that are intended to kill fat cells and reduce visible fat bulges without surgery.
- Heat (Radiofrequency Energy, Light-Based Energy, Ultrasound): Damages the fat cells in the layer of fat under the skin and reduces the thickness of fat in the treated area.
- Non-Thermal (Photobiomodulation, Magnetic Field, Mechanical Massage or Vibration): May temporarily reduce circumference of the body in the treated area.
Risks Associated with Non-Invasive Body Contouring Technologies
As with any medical procedure, there are risks and complications associated with using body contouring devices. Complications reported for all body contouring devices may include:
- Pain or discomfort
- Redness
- Swelling
- Bruising
- Nodules
Maintaining Results
Maintaining long-term results requires a healthy lifestyle. Diet plays a crucial role, as eating balanced meals helps keep off the fat that has been reduced. Exercise is equally important.
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