If you are comparing fat freezing vs ultrasound cavitation, it usually means you are not trying to lose weight in general. Most people who reach this stage are already close to their natural or target weight, but are frustrated by one or two stubborn fat areas that simply do not respond to diet or exercise.
These areas often include:
- Lower abdomen
- Upper abdomen
- Flanks (love handles)
- Inner or outer thighs
- Upper arms
- Lower back
- Under the chin
This situation is extremely common, and it is not a failure of willpower or discipline. It is a consequence of how human fat biology actually works.
Modern non-surgical fat reduction treatments were developed specifically to address this problem. Among these, fat freezing (cryolipolysis) and ultrasound cavitation are two of the most widely used and most researched technologies.
They are often discussed as if they are competitors. In reality, they work in completely different ways, affect fat tissue through different biological mechanisms, and are used for different purposes in clinical practice.
This guide will explain, in clear and medically grounded terms:
- Why some fat is so resistant to change
- What non-surgical fat reduction can and cannot do
- Exactly how fat freezing works inside the body
- Exactly how ultrasound cavitation works inside the body
- What clinical studies show for both
- The real differences between them
- Why clinics sometimes combine them
- Who each treatment is suitable for
- And how to make a sensible, informed choice
You can also read the full individual treatment pages here:
Fat Freezing (Cryolipolysis)
Ultrasound Cavitation
Why Some Fat Is So Stubborn
The body stores fat in two main compartments:
- Visceral fat — deep fat stored around the internal organs
- Subcutaneous fat — fat stored under the skin
Non-surgical fat reduction treatments only work on subcutaneous fat. They do not affect visceral fat.
However, even within subcutaneous fat, not all fat behaves the same way.
Medical research in endocrinology and metabolism has shown that certain fat areas:
- Have poorer blood supply
- Have a higher concentration of alpha-2 adrenergic receptors (which actively inhibit fat breakdown)
- Are therefore biologically resistant to lipolysis (fat burning)
This means that some fat deposits are genetically and hormonally programmed to be harder to lose, even in people who exercise regularly and eat well.
This is why:
- You cannot reliably “spot reduce” fat with exercise
- You can lose weight but still keep fat in specific areas
- Two people with the same lifestyle can have very different fat distribution
A scientific explanation of regional fat metabolism and receptor behaviour can be found here
Non-surgical fat reduction treatments were developed to bypass these biological limitations by acting directly on the fat tissue itself.
What Non-Surgical Fat Reduction Can and Cannot Do
Non-surgical fat reduction refers to medical devices that target fat tissue directly, without:
- Surgery
- Needles
- General anaesthetic
- Cutting or stitches
It is extremely important to understand what these treatments are not:
- They are not weight loss treatments
- They do not treat obesity
- They do not replace diet or exercise
What they are designed to do is:
Reduce the thickness and shape of specific, localised fat deposits.
Think of this as body contouring rather than weight loss.
Most patients who get good results are:
- Already at a relatively stable weight
- Already living reasonably healthy lifestyles
- But have one or two areas that simply do not change
Fat Freezing (Cryolipolysis)
Full Fat Freezing treatment page
What Is Fat Freezing?
Fat freezing, medically known as cryolipolysis, is a non-invasive treatment that reduces fat by selectively destroying fat cells using controlled cooling.
The scientific basis for this treatment comes from a very simple but important observation:
Fat cells are more sensitive to cold injury than skin, nerves, blood vessels, or muscle.
This means that if fat tissue is cooled in a precise, controlled way, fat cells can be damaged without harming the surrounding structures.
How Fat Freezing Works Inside the Body
During a fat freezing treatment:
- The applicator draws the fat tissue into a controlled cooling chamber
- The tissue is cooled to a temperature that specifically stresses fat cells
- Inside fat cells, the lipid (fat) content crystallises before water-rich tissues do
This process triggers:
- Cellular stress
- Inflammatory signalling
- Apoptosis, which is programmed fat cell death
Over the following 6 to 12 weeks:
- The immune system recognises the damaged fat cells
- Macrophages and other immune cells gradually break them down and remove them
- The fat layer in the treated area slowly becomes thinner
This mechanism was first described in the original cryolipolysis research
Later histological studies confirmed:
- Inflammatory fat clearance
- Gradual reduction in fat layer thickness
- No structural damage to skin, nerves, or muscle:
What Clinical Studies Show About Fat Freezing
Multiple large, peer-reviewed clinical studies show:
- An average 20–25% reduction in fat layer thickness in treated areas
- Measured using ultrasound and MRI
- Progressive improvement over 2–3 months
A major multicentre safety and efficacy review can be found here (PubMed Central Study)
Importantly:
Fat freezing reduces the number of fat cells, not just their size.
This is why results are considered long-term, provided body weight remains stable.
What Fat Freezing Is Best For
Fat freezing is particularly well suited to:
- Clearly defined, pinchable fat pockets
- Abdomen, flanks, thighs, arms, chin, and back
- People who are close to their natural or target weight
- People who want structural reduction of a fat bulge
Limitations of Fat Freezing
Fat freezing:
- Is not weight loss
- Does not treat visceral fat
- Does not tighten loose skin
- Works gradually, not instantly
It changes volume and shape, not overall body weight.
Ultrasound Cavitation
Full Ultrasound Cavitation treatment page
What Is Ultrasound Cavitation?
Ultrasound cavitation is a non-invasive treatment that uses low-frequency ultrasound waves to create mechanical pressure changes inside fat tissue.
Unlike fat freezing, cavitation does not rely on temperature. It relies on sound-wave energy and mechanical forces.
How Cavitation Works Inside the Body
During cavitation:
- Ultrasound waves pass through the skin into the fat layer
- These waves create:
- Compression cycles
- Expansion (rarefaction) cycles
In the fluid between cells, this leads to:
- Formation of tiny microbubbles
- These bubbles expand and collapse (the “cavitation effect”)
This process:
- Places mechanical stress on fat cell membranes
- Increases their permeability
- Can partially disrupt fat cells
- Causes release of:
- Triglycerides
- Fatty acids
These are then processed by:
- The lymphatic system
- The liver
- Normal metabolic and excretory pathways
A technical explanation of cavitation physics in tissue
What Clinical Studies Show About Cavitation
Clinical studies generally show:
- Reduction in body circumference measurements
- Reduction in fat thickness
- Improvement in tissue texture and smoothness
An example clinical study on waist circumference reduction
A broader review of non-invasive ultrasound body contouring
Limitations of Cavitation
Cavitation:
- Does not reliably destroy fat cells
- Primarily affects fat cell contents, not fat cell number
- Requires multiple sessions
- Depends heavily on:
- Lifestyle
- Hydration
- Metabolism
This means:
Cavitation is best understood as a fat-mobilisation and refinement treatment, not a permanent fat-cell removal treatment.
Fat Freezing vs Ultrasound Cavitation: The Real Differences
| Feature | Fat Freezing | Cavitation |
| Primary effect | Destroys fat cells | Empties / disrupts fat cells |
| Permanence | Long-term | Maintenance-based |
| Speed | Slow, gradual | Faster visual change |
| Purpose | Structural reduction | Refinement and smoothing |
They are not interchangeable treatments.
They solve different parts of the same problem.
Why Clinics Sometimes Combine Them
In medicine, it is very common to combine treatments that work through different mechanisms.
In fat reduction:
- Fat freezing changes the structure (number of fat cells)
- Cavitation improves function and clearance (movement and processing of fat)
Cavitation is often used:
- After fat freezing
- To help mobilise remaining fat
- To improve smoothness
- To support lymphatic drainage
Example Patient Case (Illustrative)
Patient: Joanna R, 38
Concern: Localised lower abdominal fat despite a healthy lifestyle
Plan:
- 1 fat freezing session
- 6 cavitation sessions over 8 weeks
Result at 12 weeks:
- 4.1 cm reduction in the lower abdomen
- Visible contour improvement
- Body weight unchanged
This demonstrates:
This is body contouring, not weight loss.
Which Should You Choose?
- If you want a permanent reduction of a specific fat bulge → Fat Freezing
- If you want smoothing, refining, or supportive treatment → Cavitation
- Many patients benefit from both when used intelligently.
Safety and Medical Boundaries
Both treatments:
- Are non-surgical
- Have strong safety records
- Are supported by clinical literature
Large cryolipolysis safety review
They are:
- Not obesity treatments
- Not weight loss solutions
- Not substitutes for lifestyle management
Book Fat Freezing in the UK
| Location | Book |
| Birmingham | Fat Freezing Birmingham |
| Manchester | Fat Freezing Manchester |
| London | Fat Freezing London |
| Belfast | Fat Freezing Belfast |
| Glasgow | Fat Freezing Glasgow |
| Leeds | Fat Freezing Leeds |
| Liverpool | Fat Freezing Liverpool |
| Nottingham | Fat Freezing Nottingham |
| Cardiff | Fat Freezing Cardiff |
| Sheffield | Fat Freezing Sheffield |
| Newcastle | Fat Freezing Newcastle |
Book Ultrasound Cavitation in the UK
| Location | Book |
| Birmingham | /clinics/birmingham/ultrasound-cavitation/ |
| Manchester | /clinics/manchester/ultrasound-cavitation/ |
| London | /clinics/london/ultrasound-cavitation/ |
| Belfast | /clinics/belfast/ultrasound-cavitation/ |
| Glasgow | /clinics/glasgow/ultrasound-cavitation/ |
| Leeds | /clinics/leeds/ultrasound-cavitation/ |
| Liverpool | /clinics/liverpool/ultrasound-cavitation/ |
| Nottingham | /clinics/nottingham/ultrasound-cavitation/ |
| Cardiff | /clinics/cardiff/ultrasound-cavitation/ |
| Sheffield | /clinics/sheffield/ultrasound-cavitation/ |
| Newcastle | /clinics/newcastle/ultrasound-cavitation/ |
Final Summary
Fat freezing and ultrasound cavitation:
- Work in different biological ways
- Are not competing treatments
- Are often complementary when used properly
The right approach depends on:
- Your body
- Your fat type
- Your goals
- Your expectations
