Fat transfer moves fat from one part of your body to another, using liposuction to harvest fat cells and then injecting them into an area that needs volume. The procedure works because your own living fat cells can establish a blood supply in their new location and survive there long-term. Between 30% and 80% of transferred fat typically survives permanently, depending on the technique used and the area treated.
The Three Core Steps
Every fat transfer follows the same basic sequence: harvest, process, inject. Your surgeon starts by numbing a donor area (often the abdomen or thighs) with local anesthetic, then makes a small incision and inserts a thin tube called a cannula connected to a syringe. Fat is gently suctioned out, essentially a limited, targeted form of liposuction.
The raw fat that comes out isn’t ready for injection. It contains blood, fluid, oil from damaged cells, and debris that all need to be removed. Surgeons purify the fat using one of two main approaches: spinning it in a centrifuge or filtering it through a sieve and washing it with saline. Centrifuging separates the fat into three layers: oil from ruptured cells on top, usable fat in the middle, and blood and fluid on the bottom. The middle layer is kept. Filtration achieves roughly the same result by physically straining out the unwanted material. Both methods concentrate the healthiest fat cells into small syringes for injection.
Placement is the most technique-dependent step. The surgeon inserts a needle or cannula into the target area and deposits tiny parcels of fat in a grid-like pattern, passing the needle back and forth to lay down thin threads of tissue across multiple layers. This micro-droplet approach maximizes the amount of fat that lands close to existing blood vessels, which is critical for survival. Dumping fat in large clumps would starve the cells in the center.
How Fat Cells Survive in a New Location
When fat cells are first injected, they have no blood supply. They’re surviving purely on nutrients that seep in from surrounding tissue, the way a sponge absorbs water from a wet surface. This diffusion can only reach so far, which is why the graft naturally develops three zones: an outer ring where cells get enough nutrition and survive, a middle zone where inflammation kicks in and the body works to build new blood vessels, and a central zone where cells are simply too far from any nutrient source and die.
The cells that survive long-term are the ones that get reconnected to your circulatory system quickly enough. Your body begins growing new blood vessels into the grafted fat within the first several days. Once those vessels are established, the fat cells function just like the fat that was always there. They respond to weight gain and loss, they produce hormones, and they persist for years. Fat cells that don’t get vascularized in time die within the first day or two of oxygen deprivation, and the body gradually absorbs them over the following weeks.
This biology explains why technique matters so much. Spreading the fat in thin layers across a wide area gives more cells access to that critical early diffusion period and shortens the distance new blood vessels need to travel.
Where Fat Transfer Is Used
The most common cosmetic applications include adding volume to the face (filling under-eye hollows, building up cheekbones, plumping lips), augmenting the breasts, and enlarging the buttocks. The Brazilian butt lift, one of the most popular cosmetic procedures worldwide, is a fat transfer. Surgeons also use it to smooth wrinkles on the hands, refine the waist-to-hip ratio, and restore volume lost to aging.
On the reconstructive side, fat transfer plays a significant role in breast reconstruction after cancer surgery, repairing facial scarring, and correcting contour irregularities left by previous procedures. Because the material is your own tissue rather than an implant or synthetic filler, the body generally tolerates it well with minimal risk of allergic reaction.
Does the Donor Site Matter?
The lower abdomen and inner thighs contain a higher concentration of stem cells found in fat tissue, which are believed to help grafted fat survive by promoting new blood vessel growth and regenerating fat cells. This has led some surgeons to prefer these areas as harvest sites. However, multiple studies comparing fat harvested from different body regions found no significant difference in how well the grafted fat actually survived. In one study, fat taken from the abdomen, thigh, flank, and knee showed equivalent cell viability both before and after processing.
In practice, most surgeons choose a donor site based on where you have enough fat to spare and where removal will give you the most cosmetic benefit, rather than chasing marginal differences in stem cell counts.
How Much Fat Survives
This is the most important variable in fat transfer, and the range is wide. On average, 50% to 70% of injected fat survives long-term. Some patients retain as much as 80%, while others keep as little as 30%. Your body absorbs the rest over the first few months as non-viable cells break down.
Surgeons typically account for this absorption by slightly overfilling the target area. You’ll look more swollen than your intended result immediately after the procedure, and the final volume settles as absorption runs its course. In some cases, a second session is needed to reach the desired result. Once the surviving fat has fully integrated with its new blood supply, results are considered permanent, unlike dermal fillers that need yearly maintenance.
Recovery Timeline
You’ll deal with swelling in two places: the donor site and the area that received the fat. The injection site typically calms down within two to three weeks. The donor site takes longer, with swelling lasting four to six weeks, though most patients find it noticeably improved by three to four weeks. Bruising is common at both sites in the first week or two.
Most people return to desk work within a week, though physical activity is restricted for several weeks to protect the grafted fat. Compressing or putting pressure on the treated area too early can damage fragile new blood vessels before they’re fully established, reducing how much fat survives.
Risks and Complications
The most characteristic complication is fat necrosis, where grafted fat cells die and form firm lumps under the skin. As these dead cells break down, they can release their oily contents into a pocket called an oil cyst. Over time, the walls of these cysts may harden with calcium deposits. Fat necrosis can sometimes be felt as a lump or seen on imaging, which in the breast can complicate future mammogram readings. In severe cases, necrosis can cause a reconstructive procedure to fail entirely or require a return to the operating room for correction.
Infection is possible but rare. Asymmetry and under-correction are more common concerns, usually addressed with a follow-up session rather than considered true complications. The Brazilian butt lift carries a unique risk profile because injecting fat too deeply near large blood vessels in the buttock can cause a fat embolism, a potentially fatal event where fat enters the bloodstream. This risk has led to updated safety guidelines that emphasize injecting fat only into the layer just beneath the skin.