Why does the face sag?

Sagging Is Not a Single Event

The change you see in the mirror cannot be explained by a single cause, because sagging does not happen in just one tissue.

The face is made up of layers stacked on top of one another. At the top is the skin. Beneath it are the subcutaneous fat (the fat layer under the skin) and the fibrous network that holds this fat together. Next comes a superficial layer of muscle and connective tissue called the SMAS. Below that lie the deep fat compartments, and at the very bottom is either the periosteum (the membrane covering the bone) or a connective tissue membrane called the deep fascia. This order varies between areas of the face, but the basic arrangement stays the same.

With age, all of these layers change. Researchers suggest looking at this process from the inside out, that is, from the bone towards the skin. Each layer undergoes its own change: the skeleton is remodelled, the fat pads shrink or shift, the tension (tone) and thickness of the muscles change, and the skin becomes thinner and weaker.

In the mirror you see a single change, but beneath it lie several processes that progress independently of one another, each taking place in a different layer.

What Changes in the Skin

The firmness of the skin is largely determined by the dermis, the middle layer of the skin. The supporting tissue between the cells here (the extracellular matrix) is produced mainly by cells called fibroblasts; collagen and elastin fibres also come from these cells.

As fibroblasts age, they weaken in two ways at once. On the one hand, the cell wears out from within: the protective regions at the ends of the chromosomes (telomeres) shorten, the cell’s energy-producing mitochondria work less well, and signalling pathways inside the cell are disrupted. On the other hand, the cell switches to an ageing-related pattern of secretion: it starts releasing messenger substances that increase inflammation and enzymes that break down the supporting tissue. Together, these two changes upset the balance between building up and breaking down. Studies describe this picture as a self-sustaining vicious circle.

In the skin, this shows in three ways: lines deepen, elasticity decreases and the skin’s protective barrier function weakens. The skin becomes thinner, and after being stretched it returns to its original shape more slowly.

The effects of this cycle are not limited to the dermis. According to research, the substances released by ageing fibroblasts disrupt the function of the keratinocytes (the cells in the upper layer of the skin), the distribution of pigment (melanin) and the skin’s immune defences; the function of small blood vessels and fat tissue is also affected. This is why the skin cannot be considered separately from the neighbouring layers.

There is an important distinction here: changes in the skin alter the surface and the quality of the tissue, but on their own they do not pull a mass of tissue downwards. The part of sagging that involves tissue mass comes from the layers beneath.

The Sun Adds Damage Independent of Age

Intrinsic ageing happens to everyone and progresses with age. A second process is added on top: damage left by external factors. Among these factors, long-term sun exposure accounts for the largest share. Ageing caused by the sun is called photoageing and is studied as a separate topic.

The basic mechanism can be summed up as follows: ultraviolet (UV) rays activate enzymes that break down the supporting tissue, and breakdown overtakes production. Recent research shows that other signalling pathways and molecules are also involved in this process. The visible result is lines and discolouration; these changes are reported to progress differently depending on skin type.

This is one of the factors that explain why the faces of two people of the same age do not look the same: how much sun they have had over the years sets them apart. These studies also look separately at the role of sun protection in reducing photoageing.

Facial Fat Is Not One Piece

For a long time, facial fat was thought to be a single, continuous layer. Anatomical studies have shown that this is not the case: the fat in the face lies in separate pads, divided from one another by fibrous partitions.

These pads sit at two separate levels. The superficial ones lie above the SMAS, under the skin; the deep ones lie below the SMAS, closer to the bone. Their roles also differ: the deep compartments provide structural support for the mid-face and for the superficial fat above them.

This distinction is not just an anatomical detail; it directly shapes how the face looks. A loss of fullness in the face means very different things depending on which level of compartment has shrunk. When a deep compartment withdraws its support, everything above it loses its foundation; when a superficial compartment shrinks, the change is seen more at the surface, in the contours themselves.

Fat Both Shrinks and Shifts

Imaging studies show that two changes take place together in the fat compartments.

The first is volume loss. In a study comparing MRI scans of the same people taken years apart, all of the superficial fat compartments in the mid-face showed a statistically significant decrease in volume and thickness. This study found no significant difference between women and men.

The second is a shift in position. In the same study, the upper and middle compartments narrowed while the lower compartment widened. The researchers interpret this as a downward shift of volume within the superficial fat. In other words, fat does not simply melt away; some of it moves.

One more finding completes the picture. In an ultrasound study, the superficial fat compartments of the mid-face were seen to move clearly upwards during smiling, while the deep compartments stayed in place. In short, the superficial layer is mobile and the deep layer is relatively fixed. This is why the mobile layer shifting over time and the fixed layer losing its supporting role lead to different changes in the face.

Underneath, the Bone Recedes

The facial skeleton is not a fixed frame that stops changing in adulthood. It is remodelled throughout life, and this change does not happen to the same degree in every area.

Recent research shows that bone loss (bone resorption) is concentrated at the rims of the eye socket (orbit), in the upper jaw (maxilla) and in the lower jaw. According to the measurements collected in this research, by the seventh decade of life the opening of the eye socket widens by an average of 15–20%, the height of the upper jaw decreases by 8–15% and the angle of the lower jaw increases by 3–7 degrees. The change around the eyes appears more marked in women, and the remodelling of the lower jaw appears more marked in men.

Another study confirms this picture from a completely different source. Measurements of a medieval skeletal collection showed that the eye sockets and the bony opening at the entrance to the nose (the pyriform aperture) tended to widen with age; in men, this increase reached statistical significance. In women, the height of the upper jaw and the height of the right branch (ramus) of the lower jaw decreased significantly. In people without teeth, both sexes were found to have wider eye sockets and less height in the upper and lower jaws.

Bone matters because all the soft tissues above it rest on it. When this supporting surface shrinks, the tissue above cannot stay where it was, even if its volume stays the same.

Why the Eye Area Shows Ageing First

For most people, the area around the eyes is where ageing is noticed first. There is an anatomical reason for this: several processes overlap here.

On the bone side, the opening of the eye socket widens; this is one of the places in the face where bone loss is most marked. According to research on ageing around the eyes, on the soft tissue side the skin, fat, muscle and fascia also move downwards, while the underlying bone, cartilage and teeth can lose mass.

The pattern of this change is not the same in everyone. Studies report significant differences between the sexes and between ethnic groups in hollowing around the eyes, drooping eyelids (ptosis) and skin elasticity; for some groups, there is not yet enough data.

There is another reason why this area is noticed early: according to research, in most people the signs of ageing around the eyes become visible long before the change is complete. So the eye area showing ageing early does not mean the process moves faster there; the overlapping changes are concentrated in a small area, and this makes them visible early.

This is why it is hard to read about what happens around the eyes and apply it directly to yourself. An article can explain the mechanism; only a doctor who examines you can tell you how these changes are distributed in your face.

The Ligaments Holding the Tissue Loosen

The soft tissues of the face do not hang in empty space. At certain points, they are attached to the deeper tissues and to the bone by fibrous structures called retaining ligaments. It is these ligaments that hold the structure of the face in place.

Research directly links the loosening of these ligaments with age to sagging, jowls (sagging along the jawline) and volume moving downwards. When a ligament loosens, the tissue above it slides down; tissue builds up on one side of the ligament and a hollow forms on the other. Some of the sharp lines you see on your face are exactly these transition points.

Research highlights one more point: the anatomy of these ligaments varies from person to person, so planning also needs to be tailored to each person. Where the ligaments have loosened, and by how much, cannot be read from a standard map.

SMAS: The Supporting Layer in Between

SMAS stands for superficial musculoaponeurotic system (an aponeurosis is a flat, tendon-like type of connective tissue). It is a network of fibrous and muscle tissue that runs between the subcutaneous fat and the deep fat. Some of the muscles that create facial expressions lie within this network, and this is also the structure that transmits the movement of the deeper tissues to the skin.

This layer is not the same in everyone. According to research on how the SMAS develops, how this layer attaches to the deeper tissues, whether it exists as separate layers, and the nature of its connective tissue sheet (fascia) component are all still debated. It is thought that this developmental process may also explain the anatomical differences seen during surgery.

The conclusion for you is simple: this intermediate layer of the face does not have the same thickness or the same position in everyone. Being the same age does not mean having the same pattern.

The layered arrangement itself is not the same everywhere in the face either. Research shows that the five-layer structure varies from area to area, and that this variation becomes even more marked when the lines along which the ligaments run are taken into account. In one area of the face the layers are clearly separate from one another, while in another they merge into each other.

Layers Change Together, but Not at the Same Rate

All of these changes happen in the same face, but not at the same rate. That is why researchers see assessing ageing layer by layer, and telling which layer stands out, as the starting point for planning.

In practice, three distinct patterns can be described. In some faces, the main change is in the skin: the quality and firmness of the tissue have decreased, but there is no shift in tissue mass. In other faces, the main change is in volume: the fat compartments have shrunk, the support from the underlying bone has decreased and the contours have sunk inwards. In others still, the main change is in position: the tissue mass has moved downwards and the ligaments have loosened.

In most faces, these three patterns are not seen on their own but together. Which one dominates cannot be predicted from age: all the measurements in research are averages, and the differences between individuals are hidden behind those averages. Research on bone also draws direct attention to this variability.

So the honest answer to the question “Why is my face sagging?” is not a single point: it depends on which layer stands out in your face.

Limits of This Article and What Comes Next

This article does not make a diagnosis and does not recommend any treatment method. What it explains is the mechanism, that is, what happens in the tissue. Which layer stands out in your face becomes clear at a consultation, not from this page.

The treatments performed at the clinic are hyaluronic acid (HA) fillers, collagen-stimulating fillers, thread lifts with dissolvable (absorbable) threads, botulinum toxin and mesotherapy. Each of these treatments is described on its own page, which covers its scope, its limits and what happens afterwards. The pages most closely related to this article are Liquid Facelift with Collagen Stimulators, French Thread Lift and Chin and Jawline Filler.

One more thing needs to be said clearly: none of the changes in the layers described above is reversible. The sources this article is based on do not describe any treatment that stops the bone from receding, the ligaments from loosening or the fat compartments from shifting. What can be done is to identify which layer’s change is shaping your appearance and to try a treatment that matches that layer; this is not equally possible in every case.

This article is limited to explaining what is happening in your face. What comes next is for you to weigh up yourself, taking into account what you have read as well.