Volume Loss or Sagging?

Sagging: One Word, Two Separate Processes

When people look in the mirror, they usually describe the change they see with a single word: sagging. Yet beneath that word lie two different processes.

The first is volume loss: the tissue has diminished. An area that used to be full now contains less tissue; the surface sinks inwards and the light falls on it differently.

The second is descent: the tissue has not diminished; it has moved down. The same mass is still there, but it sits lower than before.

This distinction is not just an academic nicety. The understanding of facial ageing has moved on from a time when it was explained by gravity alone to one in which changes in volume are also taken into account. This shift began when it was shown that facial fat is made up of compartments with defined boundaries. So saying “it’s sagging” does not yet tell you what is actually happening.

The distinction matters for you too. What you see in the mirror is the result, not the mechanism; the same shadow and the same line can have two different causes. Knowing which one stands out in your face determines where the conversation at your consultation begins.

What Happens to the Tissues in Volume Loss

In volume loss, the tissue itself diminishes, and this reduction is not limited to a single layer.

Facial fat is not one continuous layer; it is made up of compartments with defined boundaries. In a study that compared magnetic resonance imaging (MRI) scans of the same people taken years apart, the superficial fat compartments of the mid-face, those lying close to the skin, showed a significant decrease in both volume and thickness. This decrease occurred in both women and men.

The bone underneath changes too. Research on the ageing facial skeleton reports region-specific bone loss (bone resorption) and remodelling around the eye socket (orbit), in the upper jaw (maxilla) and at the angle of the lower jaw. Bone is the foundation on which the soft tissue rests; when that foundation recedes, the appearance changes even if the tissue above it has not diminished at all.

So volume loss does not simply mean “the fat has melted away”; the foundation the tissue rests on may also have become smaller.

The loss does not progress at the same rate in every area. This difference between fat compartments is reported to be linked to the different mechanical and biological environments in which the deep and superficial fat pads sit. That is why in one face the temples and the under-eye area show it early, while in another the central part of the cheek may flatten first.

What Happens to the Tissues in Sagging

In descent, what changes is not the amount of tissue but its position.

Not every layer of facial fat is equally mobile. In an ultrasound study, measurements showed that during smiling the superficial fat compartments of the mid-face moved upwards by an average of 3.7 mm, while the deep compartments stayed in place. In other words, the face has one layer that moves and one that hardly moves at all.

The structures that hold the tissue in place, the facial retaining ligaments, also change. Age-related loosening of these ligaments is reported to contribute to sagging, to jowls along the jawline and to the downward movement of tissue.

Put these two findings together and the picture becomes clear: the mobile layer moves down when the ligament holding it loosens. Nothing has been lost; something has moved.

Descent leaves recognisable signs. Because the retaining ligaments hold the tissue along particular lines, the result does not look the same everywhere on the face; jowls along the jawline are one example.

Both Occur Together in the Same Face

In real faces, these two processes do not stay separate.

The same study that compared MRI scans of the mid-face taken years apart shows this clearly: the width of the superficial fat compartments decreased in their upper and middle parts but increased in their lower part. The researchers interpret this as a shift of volume within the superficial fat itself. So both a reduction and a downward shift were measured in the same area at the same time.

That is why the right question is not “Which one is present?” but “Which one dominates?” The job of the consultation is not to choose one of the two but to see which one is shaping the picture.

This is exactly what a mirror cannot do. A mirror shows you the sum of the two processes; it does not show how much each one contributes. So looking at your own face and saying “this is sagging” may be right, but it may also be incomplete.

What Changes When You Lie Down, and What Doesn’t

One of the simplest ways to tell the two apart is to remove the effect of gravity.

Research has reported that the soft tissue of the face shifts position between sitting and lying down, and that this difference becomes more pronounced in faces with laxity. In a study that measured and compared photographs taken in the sitting and lying positions, this shift was shown in numbers, and the researchers stressed that it is important to assess laxity in the sitting position.

In practice, this means the following: a finding that improves when you lie on your back is related to descent, because the tissue has slid back. A finding that stays the same when you lie down cannot be explained by descent; in that case, there is either missing volume or a change in the structure of the tissue itself.

This observation alone is not enough to make a diagnosis. Both kinds of finding can be present in the same face, and you cannot tell at a glance which one predominates, or by how much.

What Supporting the Cheekbone Shows

The second observation concerns the cheekbone area.

In a step-by-step method developed for assessing under-eye shadows, the examination does not end with looking. The steps are:

• Visual inspection under suitable lighting.
• Separate examination of the cheek and the under-eye area.
• Examination of the eye socket rim and the soft tissue by hand.
• Determining the front-to-back relationship between the eyeball and the cheekbone.
• A separate assessment of skin quality.

In the same study, all the doctors who took part in the survey agreed that mid-cheek volume is decisive when under-eye hollows are being addressed.

This is where supporting the area below the cheekbone upwards with your hand is useful. If the shadow under the eye and the flattening of the cheek both ease when this support is given, what is shaping the picture is most likely not the under-eye area itself but the neighbouring area just below it.

An international consensus statement reflecting the shared view of experts points in the same direction: assessment is not only visual; examination by hand and observing how the tissue behaves in motion are separate steps, and it is the person who is assessed, not a photograph.

These two observations are used together. If a finding that changes when you lie down and a finding that eases with support from your hand point in the same direction, the picture is mainly one of descent; if neither changes, volume loss and tissue quality come to the fore. This is not a diagnosis; it is a way of organising the observations you bring to your consultation.

Under the Eyes: Where the Two Are Most Easily Confused

The under-eye area is where volume loss and descent are most easily confused, because both create the same shadow.

Research on treating under-eye hollows with hyaluronic acid (HA) filler recommends treating volume loss in the mid-face first to achieve a natural-looking result, and states that the under-eye area can be treated directly if this is not enough. This is where the order comes from: the under-eye area itself cannot be assessed until support from the neighbouring area is in place.

This research also stresses that patient selection needs to be based on defined criteria, and that the benefit of the treatment needs to be weighed against the risk of irregularities or of the filler becoming visible. In this area, the price of going ahead without making the distinction is not just “getting no result”.

The “vector”, a separate step in under-eye assessment, also becomes important here: it describes whether the eyeball sits forward of or behind the cheekbone. This relationship changes how the same amount of volume looks. The vector differs from person to person and is assessed not just by looking but together with an examination by hand.

Rapid Weight Loss Complicates the Picture

In recent years, a new factor has emerged that makes this distinction harder: rapid weight loss.

Research on how medication-assisted rapid weight loss affects the face reports that several changes occur together in this process: deflation of the superficial fat compartments, reduced deep support, bone loss (bone resorption) and skin laxity. According to this research, volume loss in the mid-face occurs mainly in the superficial compartments and leads to flatter facial contours and more visible transition lines between areas.

In the mirror, this looks like sagging, but the mechanism behind it is largely deflation. If you have lost a noticeable amount of weight over a short period, this needs to be taken into account when interpreting the change you see in the mirror. Which layers are affected, and to what extent, is seen at a consultation.

An international consensus statement prepared for this group of patients also lists the skin and the superficial and deep fat pads as the layers most affected by rapid weight loss. For assessment, it names three-dimensional volume analysis as a quantitative method, and photo-based scales and patient-reported outcome measures as qualitative methods.

Why the Wrong Distinction Leads to the Wrong Treatment

When the distinction is made wrongly, the treatment carried out also misses its target. The reason is not the methods themselves but which findings they correspond to.

In a face where volume loss dominates, the main problem is not the position of the tissue. Methods based on repositioning tissue do not replace missing volume; lifting deflated tissue upwards does not fill the areas where the surface has sunk in.

The opposite mistake has more visible consequences. Research on overfilled faces shows that this condition is not caused by excess volume alone but by several factors acting together: filler placed in a layer or used for a finding where it does not belong (anatomical mismatch), disruption of the way the tissues move (biomechanical disruption) and the accumulation of repeated treatments. The main findings are distorted facial contours at rest and unnatural movement during facial expressions. Anatomical knowledge and individual planning are cited as the way to reduce the risk of this condition.

When descent dominates, the mechanism is different. Anatomical studies on thread lifts state that a lasting lift requires the fat compartments to be addressed correctly and the retaining ligaments to be included in the support. According to these studies, reducing the risk of tissue distortion while doing this depends on anatomical knowledge.

The question is not which method is superior, but which mechanism matches your findings.

How the Distinction Is Recorded

For a change seen at a consultation to be followed over time, it needs to be measurable.

Validated visual scales have been developed to grade the degree of volume loss. One of these is a five-grade, photo-based scale for volume deficit in the mid-face. This scale has been reported to be reproducible with high agreement, both from photographs and in face-to-face assessment, and to distinguish a one-grade difference in a clinically meaningful way.

A scale like this creates a common language. At your next consultation, instead of saying “it has changed a bit”, you can discuss which grade of the scale you are at; this also makes it easier for you to understand your own situation.

Measurement alone is not enough either. International consensus statements separately emphasise using quantitative and qualitative methods together, not limiting assessment to looking alone, and recording the person’s own expectations. A scale is not a decision; it is the foundation on which the decision is built.

The Limits of This Distinction

This distinction has its limits too, and it is important that you know them.

First: observing your face lying down and supporting the cheekbone are rough observations you can make yourself; they are not a substitute for a diagnosis. Sources that define the steps of assessment consider them together with steps such as lighting, examination by hand and observation in motion; none of these is considered sufficient on its own.

Second: the two occur together. As the MRI measurements show, both can be present in the same area at the same time; so saying “I only have this one” is often incomplete.

Third: not every situation can be addressed to the same extent. The information here explains how the two processes progress in the tissues; it does not tell you how much a given approach can achieve for a given person. The relationship between the degree of laxity and the scope of non-surgical approaches is not a matter for a general statement; it needs to be discussed openly at a consultation.

Fourth: what is described here is the mechanism, not suitability. What may be considered for whom is decided at a consultation, not by an article.

Treatments Offered Here

The clinic offers hyaluronic acid (HA) fillers, collagen-stimulating fillers and thread lifts with dissolvable threads. Which of these may be considered is assessed at a consultation, based on which of the two processes dominates. You can find details of these treatments on the Liquid Facelift with Collagen Stimulators, French Thread Lift and Chin and Jawline Filler pages.

You do not have to describe what you see in the mirror with a single word. The aim of this article is not to recommend a method to you but to show how the two processes differ from each other. Working out with your doctor at a consultation which finding stands out in your face is the first step towards deciding for yourself which path is right for you.