Fat survival after facial fat grafting: what is known so far

Why does the face lose volume, and what does fat grafting do?

Facial aging is not just a matter of wrinkles. A 2024 review explained that the loss of fat from specific fat compartments of the face with age contributes significantly to the structural aging of the face ^[1]. Autologous fat grafting is a method of harvesting fat from another part of your own body, purifying it, and injecting it into hollow areas to restore volume. The same review regarded your own fat as a preferred filler for correcting facial atrophy because it is abundant, easy to obtain, and well tolerated by the body ^[1].

Because facial aging involves both sagging tissue and volume loss, the literature notes that both need to be addressed together to achieve good results ^[4]. A 2015 review stated that in people with marked facial atrophy, skin surface treatments or lifting surgery alone often do not provide enough improvement ^[5]. The same review considered that properly performed fat grafting can bring marked and long-lasting improvement to a face that has lost volume because of age or disease ^[5]. When sagging is also present, an approach that tightens the loose tissue with a lift while restoring volume with fat (lift-and-fill) is used ^[4].

Which areas is it used for, and who is it considered for?

A 2020 review stated that areas usually treated with standard fillers, such as the temples, forehead, above and below the eyes, cheeks, around the mouth, the nasolabial folds, the jawline, and the chin, can also be contoured with fat ^[4]. Natural-looking contours that blend well with the surrounding tissue were cited as advantages ^[4]. The review also stressed that understanding the anatomy of the facial fat compartments and systematically assessing which areas have lost volume, and how much, is the key to a natural result ^[4].

A 2021 review considered that because facial aging involves sun damage, volume loss, and thinning of the skin all at once, an approach that combines several methods is needed ^[6]. In statistics from the International Society of Aesthetic Plastic Surgery (ISAPS), facial fat grafting is counted among face and head procedures, and it was also among the top five procedures most often performed on men ^[7]. However, whether fat grafting is right for you depends on how much volume loss and sagging you have, the condition of your skin, and whether there is enough fat at the area it would be harvested from, so this is decided through an examination.

How do macrofat, microfat, and nanofat differ?

Depending on the size of the tube (cannula) and the filtering method used to harvest and process the fat, grafted fat is divided into three types based on particle size and cell composition: macrofat, microfat, and nanofat ^[1]. Macrofat and microfat were described as filling hollow areas while also helping to improve skin quality, and nanofat has been reported to improve skin texture and pigmentation ^[1].

The same review stated that because each area of the face ages differently, it is important to match the type of fat to each area and make an individualized plan ^[1]. A 2021 review also presented an injection technique that replaces lost volume with fat in each anatomical compartment of the face, but because the authors rated it as level of evidence 4, it is difficult to regard its results as confirmed by comparative studies ^[6].

Why it is difficult to put a number on the survival rate

Fat grafting was first introduced in the early 20th century, but for a time it was rarely used because it was considered unreliable at maintaining volume over the long term ^[3]. Over the past 20 years, a large body of research on how fat is harvested, processed, and injected has accumulated, and its reliability has improved greatly ^[3]. However, the same review stated that long-term volume loss and absorption (resorption) of the grafted fat remain major challenges, making results difficult to predict ^[3].

A 2021 review explained that a substantial number of fat cells are lost and absorbed, so the visible volume decreases and the procedure sometimes needs to be repeated ^[2]. It stated that fat cells can be lost at all four stages of the grafting process ^[2]. A 2022 review also stated that the long-term survival and retention of grafted fat has historically been a major challenge, and that each stage of the process is being refined to improve fat survival ^[8].

The research summaries this article draws on do not include any data that give a survival rate for facial fat as a number. If you are told a specific survival rate during a consultation, it is a good idea to ask which area it was measured in, with which method, and how long after the procedure.

Methods to improve fat survival and the limits of the evidence

A number of new techniques, including methods of harvesting fat, methods of processing it, and fat grafting combined with supplementary techniques (assisted fat grafting), have been reported to improve fat cell survival, the restoration of blood supply (revascularization), and graft results ^[2]. However, the same review stated that standardized techniques and training are lacking, and that more research on fat processing and additives is needed ^[2]. In particular, it pointed out that there is very little published evidence on the techniques used to inject fat, and that current methods rely mostly on the surgeon's experience ^[2].

Methods that add stromal vascular fraction, adipose-derived stem cells grown outside the body, or platelet-derived growth factor to the fat to support its survival are being actively researched ^[3]. There is also the idea that dividing fat into smaller pieces may make it easier for the grafted cells to receive oxygen and nutrients, which could favor their survival, but this was presented as a theoretical explanation ^[3]. These techniques are at the stage of being tested in animal studies and some human studies, so it is difficult to say that their effects have been established ^[3].

Recovery, risks, and what to check during your consultation

Both the area where fat is harvested and the area where it is injected will swell and bruise, and these need time to settle. The grafted fat may also shrink more than expected or remain unevenly. The research summaries this article draws on did not address complication rates, so it is a good idea to hear specifically about possible complications and how they are managed from the specialist who examines you in person.

• Whether volume loss or sagging is the main problem
• The area where fat will be harvested and how that area recovers
• What type of fat is planned for each area
• The possibility and timing of additional procedures if the volume decreases
• Possible complications and how they are managed