Lifting Treatment Should Change with Skin Thickness and Fat Volume

In lifting consultations we are often asked, “How many mm do you fire at?” It is a good question. To answer it, however, one must first know what lies at the place those mm reach.

There is a measurement study in which the faces of 53 Korean and Thai cadavers were dissected by region and the thickness of each layer was measured. The figures that came out of it are the starting point for this whole article.

What deserves attention here is not the skin but the fat. Skin thickness moves by only about 0.5mm as the region changes. The superficial fat, however, runs from 1.6mm to 5.1mm. That is a difference of 3.5mm.

Set that beside the fact that the depth intervals of ultrasound lifting cartridges are 1.5mm → 3.0mm → 4.5mm, that is, increments of 1.5mm, and the meaning becomes clear. The variation in layer thickness that arises naturally within a single face is larger than the adjustment increment the device offers. It means that using the same cartridge on the cheekbone and on the perioral area places the energy at different anatomical positions in the two places.

This is not a defect of any particular device. That is simply how anatomy is. Which is why treating the face region by region is the basis of the procedure.

High-intensity focused ultrasound (HIFU) gathers energy at a single point, the way a lens gathers sunlight. At that point the tissue temperature rises to 60–70°C and a coagulation point of around 1mm forms; as those points heal, the tissue is drawn together.

There is a study in which the coagulation points of five devices were actually sectioned in phantoms and cadavers. What was confirmed is as follows.

• The coagulation point of the 4.5mm cartridge is placed across the superficial fat into the SMAS and, depending on the region, into the layer beneath it. This is the layer targeted in lifting.
• With the 3.0mm cartridge, coagulation was observed in front of the focus as well — that is, coagulation also occurring in the dermis. Ultrasound does not act only at the focus; it also leaves heat along the path it passes through.
• Even at the same labelled depth, the shape and position of the coagulation point differed between devices. ‘4.5mm’ does not mean the same thing when the company is different.

There is something that should be recorded honestly here. We could not find a study that directly measured in living people that an individual’s fat thickness was great enough for the focus to fall outside the target layer. Placing the measurements above beside the phantom study above, it is inferred that this is likely to happen; it has not itself been measured.

Radiofrequency works on a different principle from ultrasound. Rather than gathering a focus, it passes a current so that the tissue itself generates heat through resistance. As a result, the electrical properties of the tissue are reflected directly in the outcome.

An eightfold difference means that the same output does not produce the same result in a person with a thick fat layer and a person with a thin one. In fact, calculations have been reported showing that at the boundary between dermis and fat the current is scattered, so that the area over which half of the current gathers spreads far more widely than it would in homogeneous tissue. In a recent study using porcine tissue together with a finite element model, the thinner the fat layer, the more the temperature rose under the same conditions.

On top of this comes electrode size. In monopolar radiofrequency, penetration depth is broadly proportional to the electrode radius. A small electrode generates heat shallowly and narrowly; a large one, deeply and widely. This is why device companies release tips in several sizes.

So far this has been anatomy and physics. So then — does changing the settings actually change the outcome on a real human face? There is a study that tested this question directly.

It is a split-face trial in 31 people in which monopolar radiofrequency tips of different sizes were randomly assigned to the left and right sides of the same person’s face. One side used a 3cm² tip, the other a 4cm² tip. Because it is the same person, age · skin condition · lifestyle are completely controlled.

What this result tells us is clear. The direction that dividing the settings to suit the region is better than using one setting over the whole face has been confirmed in living people. In particular, in the periorbital area, where both skin and fat are thin, the small electrode was significantly superior. That matches the physics of the previous section exactly. Shallow places call for an electrode that reaches shallowly.

In the remaining two regions, however, although the direction favoured the larger tip, it was not statistically significant. This study did not go so far as to prove “a large tip for a large region”.

An approach in which skin and fat thickness are measured by ultrasound before the procedure and the cartridge and output are then decided from those values has been introduced recently. As an idea it sits well with everything above. So — were the results actually better?

A study published in 2026 compared an anatomy-based approach with a conventional approach over 16 weeks in 20 women aged 60 and over. The results were as follows.

• The figures on the anatomy-based side came out better. The direction is supportive.
• However, the size of the difference was 0.19–0.20mm, that is, sub-millimetre.
• There were 20 participants, and while several indicators were compared together, no correction for multiple comparisons was made.
• The paper does not state by what specific rule the ultrasound measurements led to the cartridge selection. It is therefore difficult to reproduce as it stands elsewhere.

In summary, the direction that “personalisation is better” is supported, but the evidence has not accumulated to the point where one can say “personalisation is definitely better”. This is the part of this article that must be written most honestly.

Reading this far, it is easy to conclude that thickness and fat volume govern the outcome. Yet there is a study reporting precisely the opposite. It is data that must not be left out of this article.

It is a study that followed 25 people who had received monopolar radiofrequency at 3 months · 6 months · 12 months and analysed which factors predicted treatment response. The conclusion was this.

In other words, the less lax the person, the better the lifting response, and whether the skin was thick or the fat plentiful was not nearly as decisive.

This result and the material above do not in fact conflict. It is enough to distinguish two things.

• Thickness and fat volume are — used to decide how the energy is to be delivered (depth · tip · output).
• The degree of laxity is — used to gauge how much improvement there will be once it has been delivered that way.

In consultation, the two questions are different. The first is a question of design; the second, a question of expectations. Sasaki’s data does not mean that measuring thickness is pointless; it is right to read it as meaning that one cannot promise a result from thickness alone.

The most practical reason for treating depth region by region is not results but safety.

In a review of 45 papers collecting the adverse events of ultrasound lifting, facial fat atrophy was rare, at under 1%. Considering how common the procedure is, that is a reassuring figure. What matters, though, is what those rare cases arose from. The review’s summary was “inappropriate depth selection”.

In data from a single institution that looked retrospectively at 39 people, the complication rate was 23%, and among them there were 1 case of persistent fat atrophy and 3 cases of transient reduction in lip · eyebrow movement. All are of the kind that occurs when energy is placed deeper or shallower than the intended layer.

In addition, there is literature recommending that after the deepest 4.5mm pass, repetition on the same area within 6 months be avoided. The intent is to give the tissue time to recover.

Not using a deep cartridge as it comes on places where the fat is thin — the temples, the periorbital area, the hollowed inner cheek. This is the clearest practical benefit of looking at thickness. Not in order to produce more effect, but in order not to deliver energy where it should not be delivered.

Since it is difficult to measure facial thickness every time, the question may arise whether body type could serve as a gauge. When one checks, it does not work that way.

• Several studies have reported that facial skin thickness cannot be predicted from BMI. Body fat and facial fat move independently.
• That said, in ultrasound lifting reviews there is a tendency to treat a BMI above 30 as a relative contraindication. In one small dataset, only 3 of 11 people with a BMI over 30 showed improvement. However, this is data cited through another review, and we could not verify the original source directly.

The conclusion is simple. Body type is of no help as a reference; the face has to be assessed on the face. Palpation and observation, and ultrasound where necessary, take its place.

Translated into practice, the material above comes to the following. It is a commonsense procedure with nothing to exaggerate and nothing to mystify.

1. We divide the face into regions. The temples · periorbital area · cheekbones · jawline · neck are separate areas with different thicknesses. We do not use the same setting over the whole face.
2. For thin areas we use shallow depths and small electrodes. The trial in which the small tip was significantly superior in the periorbital area supports this choice.
3. On areas where the fat is thin or hollowed, we avoid deep cartridges. This is because reviews have linked fat atrophy to ‘inappropriate depth selection’.
4. We assess the degree of laxity separately. Thickness is used for design, laxity for expectations. Where laxity is marked, we say in advance that it may go beyond what lifting devices alone can achieve.
5. We leave an interval after a deep pass. We do not repeat on the same area at short intervals.
6. We distinguish cases where volume is the problem. Whether the issue is density and texture, sagging, or hollowing changes the relative weight of skin boosters and lifting. We have set out this distinction separately in which comes first, boosters or lifting.

The devices used at Miso Clinic are XERF (radiofrequency), Density (radiofrequency), and Oligio Kiss (radiofrequency · ultrasound). The depth settings of each device and the range that has been confirmed are set out on the relevant pages.

Setting out separately what has been confirmed in this article and what has not yet been confirmed gives the following.

• Confirmed — superficial fat thickness differs more than threefold between facial regions. The electrical conductivity of fat and dermis differs by nearly eightfold. Changing electrode size produced a significantly different result in the periorbital area. Fat atrophy from ultrasound lifting is rare but is reported in connection with ‘inappropriate depth selection’.
• Inferred — a fixed-depth cartridge may fall outside the intended layer because of an individual’s difference in thickness. The direction is sound, but we could not find data measured directly in living people.
• Not yet confirmed — the proposition that measuring thickness by ultrasound and then choosing the settings produces better results. In a study of 20 people the direction was supported, but the difference was sub-millimetre and there was no correction.
• Data pointing the other way — in a follow-up study of 25 people, thickness and fat depth did not predict response, and only the degree of laxity was a predictive factor.

That is why the title of this article is not “results differ according to thickness” but “treatment should change with thickness and fat volume”. It is not a sentence that promises a result but a sentence about a principle of design. That principle is amply supported by the anatomical · physical · safety data confirmed so far.

Written and reviewed by Lee Chi-Hak, MD, medical director of Miso Clinic in Daegu, South Korea. Every study cited above is given together with its design, its size and the limitations the authors themselves recorded, and where we could not find data, we have said that we could not find any.