Fat grafting is a surgical procedure that moves fat from one part of your body to another. A surgeon removes fat (usually from the abdomen, thighs, or flanks) through liposuction, purifies it, then injects it in small droplets into an area that needs more volume. Because the fat comes from your own body, it’s also called autologous fat transfer. The procedure is used for both cosmetic and reconstructive purposes, from filling in facial hollows to smoothing out deformities left by breast surgery.
How the Procedure Works
Fat grafting happens in three stages: harvesting, processing, and reinjection. During harvesting, a surgeon uses liposuction to collect fat from a donor site on your body. Research comparing five common donor sites (flank, upper and lower abdomen, inner and outer thigh) found no meaningful difference in graft survival between them. So the choice of where to harvest typically comes down to which area has enough fat and is easiest to access safely.
Once removed, the fat needs to be cleaned. The goal is to separate viable fat cells from blood, oil from ruptured cells, and leftover fluid. Surgeons use one of three main techniques: centrifugation (spinning the fat to separate it into layers), filtration through a metal sieve with saline washing, or simple decantation (letting gravity do the work). Studies comparing these methods have found no significant difference in how well the fat survives long term. Some research suggests washing may actually preserve more intact fat cells and stem cells than centrifugation, though centrifugation produces a smoother consistency that can be useful for delicate areas like the under-eye region.
Finally, the purified fat is injected in tiny droplets into the target area. The small droplet size matters. Each droplet needs to connect with a nearby blood vessel in the surrounding tissue to survive. Droplets that don’t establish a blood supply will die and be reabsorbed by the body. This is why surgeons inject fat in many small parcels rather than one large mass.
What Happens to the Fat After Injection
Transferred fat arrives at its new location without any blood supply. Over the first week or so, stem cells within the fat tissue respond to the low-oxygen environment by releasing growth signals that encourage new blood vessels to form. This process is critical: each small fat droplet needs to pair with a capillary from the surrounding tissue in a one-to-one ratio. Any fat that doesn’t connect to a blood vessel will break down.
As the graft heals, some of the original fat cells die and are gradually replaced by a mix of new fat cells, fibrous tissue, and incoming blood vessels from the surrounding area. The fat that successfully establishes a blood supply becomes a permanent, living part of your body. It will behave like normal fat tissue, gaining or losing volume if your weight changes significantly.
Not all of the injected fat survives this process. A large meta-analysis of 27 studies covering over 1,000 patients who had facial fat grafting found that the average volume retention rate was about 47%, with individual results ranging from 26% to 83%. In practical terms, this means roughly half the volume your surgeon injects will be permanent, and the rest will be reabsorbed. This unpredictability is why some people need a second session to reach their desired result.
Common Uses
In the face, fat grafting restores volume lost to aging. The cheeks, under-eye hollows, temples, and jawline are frequent target areas. Compared to synthetic dermal fillers, fat grafting tends to last much longer. Fillers typically break down within a few months to a year and need regular touch-ups. Fat grafting results, once the surviving fat has stabilized, can last indefinitely. Some people need more than one session, but many require no future treatments after that.
For breast surgery, fat grafting serves both cosmetic and reconstructive roles. It can correct asymmetry, fill in contour defects left by a lumpectomy, or add modest volume, typically about half a cup size. If you’re looking for a larger increase of one cup or more, implants are generally a better fit. Fat grafting in the breast is also less predictable in patients who have had radiation therapy, since irradiated tissue has a reduced blood supply that makes it harder for grafted fat to survive.
Beyond the face and breasts, fat grafting is used to fill in scars, correct depressions from injuries, add volume to the hands, and reshape the buttocks (the so-called Brazilian butt lift).
The Role of Stem Cells
Harvested fat contains a significant number of adult stem cells, which are part of why fat grafting does more than just fill space. These stem cells can develop into various tissue types, including fat, cartilage, muscle, and skin. They also release growth factors that promote blood vessel formation and tissue repair, which helps the graft integrate into its new location.
A newer technique called cell-assisted lipotransfer concentrates these stem cells and adds them back into the fat before injection. A meta-analysis found that this enrichment raised the average fat survival rate from about 45% to 60% and reduced the need for repeat procedures in facial grafting by 13%. The approach is still evolving, but it points to why the biological composition of the graft matters, not just the volume injected.
Recovery Timeline
Most people experience swelling and mild soreness for seven to ten days, with a total initial recovery period of about two weeks. During this time, you’ll typically have swelling and possibly bruising at both the donor site (where fat was removed) and the injection site. Swelling that persists beyond two weeks, or that comes with significant pain or redness, is worth reporting to your surgeon promptly.
The final results aren’t visible right away. Because some of the injected fat will be reabsorbed over the first few months, what you see at two weeks is not what you’ll see at six months. Most surgeons wait at least three to six months before evaluating whether a second session is needed, giving the surviving fat time to fully stabilize.
Risks and Complications
The most common complication is fat necrosis, where some of the transferred fat cells die and trigger a localized inflammatory response. This can lead to firm, round nodules under the skin, oil-filled cysts, or calcifications. In the breast, these calcifications can sometimes make mammograms harder to read, which is an important consideration for screening. Clinically, fat necrosis can show up as palpable lumps, skin dimpling, or localized redness and swelling.
Fat embolism, where fat enters a blood vessel and travels to another part of the body, is a rare but serious risk. The small-droplet injection technique is designed in part to minimize this danger. The overall safety profile of fat grafting is considered favorable compared to synthetic implants, since using your own tissue eliminates the risk of allergic reactions or implant-related complications. Still, outcomes depend heavily on proper surgical technique, particularly on ensuring the grafted fat is placed in small enough quantities to establish a blood supply.
Who Is a Good Candidate
You need enough donor fat for the procedure to be feasible, which means very lean individuals may not have sufficient tissue to harvest. Beyond that, the procedure works across a wide range of body types. Good skin elasticity at the injection site helps produce smoother results, and realistic expectations about retention rates are important since not all injected volume will survive.
People who have had radiation to the target area, who smoke (which impairs blood vessel formation), or who have active infections at either the donor or recipient site are generally not ideal candidates. The success of the graft depends on healthy tissue at the injection site being able to grow new blood vessels into the transferred fat, so anything that compromises that process reduces the odds of a good outcome.