The questions that come with your own fat
Fat grafting under the eye is attractive for a simple reason: it uses the patient's own tissue, so there is no foreign material for the body to react to. It also raises a set of questions that filler does not. Will it survive? Can I lose weight afterward? Does it matter where the fat is taken from? What happens to fat that does not take? ST's surgeons have answered each of these in videos, and this column brings the answers together. One framing point first. Under the eye, ST treats fat grafting as a supporting procedure. The main correction for bags and grooves is repositioning — moving the patient's existing under-eye fat, with its blood supply intact, into the groove. Grafting fills what repositioning cannot: a groove deeper than the available fat, a difference between sides, or colour at the skin surface.
How grafted fat survives: moving house
ST's surgeons describe survival as moving house. Grafted fat cells arrive at a new address with no supply lines. To survive, they need new blood vessels to grow into them and bring nutrients. That process begins within days, and supply is established from around the first week, but the fat is not considered fully settled until about three months. During that window some cells take and some do not. That is why a proportion of grafted fat is always lost, why the amount varies between individuals, and why the result is judged at around three months rather than in the first weeks, when swelling also makes it look fuller than it will be.
| Period | What is happening | What it means for you |
|---|---|---|
| First days | Grafted cells depend on surrounding fluid; new vessels begin to form | Swelling makes the area look fuller than the final result |
| From about 1 week | Blood supply starts reaching the graft | Avoid pressure and massage as instructed |
| Up to about 3 months | Cells that receive supply settle; those that do not are cleared | Discuss any diet plans with your surgeon; significant weight loss is generally discouraged |
| After about 3 months | Surviving fat is established | Result can be assessed; a second session, if needed, is planned from here |
| Long term | Grafted fat behaves like your other fat | Changes with large changes in body weight |
Weight loss: before, not during
This is the practical rule that follows from the moving-house picture. While grafted cells are establishing a blood supply, they are surviving on very little. Strict dieting during that period is thought to reduce their margin further, and some cells that might have taken may be lost. ST therefore asks patients who intend to lose weight to do it before surgery where possible, and not to diet until the graft has settled, about three months after the procedure. If a second grafting session is planned, the same applies to the period after the last session. Once the fat has settled, it is simply your fat. It does not disappear selectively when you diet — weight loss draws on fat throughout the body, and grafted fat behaves like the rest. Ordinary weight fluctuation makes little visible difference under the eye, but a large gain or loss will affect grafted fat in the same direction as fat elsewhere.
Does it matter where the fat comes from?
Fat is usually taken from the abdomen or thigh, because those areas reliably provide enough. For the under-eye, the quantity needed is small, and current evidence does not show a meaningful difference in survival between common donor sites. A common belief — that thigh fat takes better than abdominal fat, for example — is not what determines the outcome. What matters far more is how the fat is processed before it is placed: how thoroughly oil, fluid, and damaged cells are removed, so that what goes in is healthy, viable tissue. Because the fat is the patient's own, there is no rejection reaction whichever site it comes from.
Why under-eye grafting can cause irregularity, and how that risk is reduced
The under-eye has some of the thinnest skin and muscle on the body. Ordinary grafted fat placed directly under that skin shows every irregularity, and small clumps or firm nodules become visible and palpable. The basic principles are therefore conservative: small quantities, placed deep, beneath the muscle or within the deeper fat layer, where the overlying tissue can hide minor unevenness. Blunt cannulas with a side opening are generally used rather than sharp needles, to reduce injury to vessels and surrounding tissue, though they do not eliminate it. When there is a reason to treat the skin layer itself — thin skin showing colour, fine surface irregularity — ordinary fat is not used. For this layer, a more finely processed fat is used, with smaller particles intended to spread more evenly than ordinary grafted fat. Because it is placed closer to the surface, its swelling can remain visible for longer than that of a deep graft. No technique eliminates the risk of irregularity entirely, which is why placement and quantity are decided conservatively.
What happens to fat that does not survive, and to fat that does
Cells that fail to establish a blood supply are not left behind as debris. The body's clean-up cells, macrophages, remove them over the following weeks, and the loss shows as a gradual reduction in volume during the first months. Fat that does establish itself is living tissue in its new location and is considered permanent, changing only as the rest of your body fat changes and as the face ages around it. This is also why under-correction is preferred to over-correction under the eye: a small top-up after three months is generally simpler to manage, while excess fat that has taken is much harder to remove. All procedures carry risks, including irregularity, firmness, oil cysts, asymmetry, partial loss of grafted fat requiring a further session, bruising or contour change at the donor site, infection, and, rarely, blockage of a blood vessel that can cause serious complications including loss of vision; results vary between individuals.