A Brazilian Butt Lift (BBL) is made of your own body fat. Unlike breast implants or other cosmetic devices, the procedure doesn’t involve synthetic materials. Fat is removed from one part of your body through liposuction, purified, and then injected into your buttocks. There are also non-surgical and implant-based alternatives that use different materials, which is worth understanding if you’re comparing options.
How Your Own Fat Becomes the Implant
The core material in a BBL is autologous fat, meaning fat harvested from your own body. Common donor sites include the abdomen, flanks, thighs, and lower back. A surgeon uses a thin steel tube called a cannula, inserted through small incisions, to suction out fat from these areas. The fat comes out mixed with blood, fluid from the numbing solution, and oil from damaged fat cells, so it needs to be cleaned before it can be reinjected.
This purification process typically involves several steps. First, the harvested fat sits undisturbed for 10 to 15 minutes so gravity can separate it into layers. The mixture may also be washed and filtered to remove debris and clumps. Then it goes through a centrifuge, a machine that spins rapidly to further separate the material into three distinct layers: oil on top, purified fat cells in the middle, and blood and fluid on the bottom. That middle layer of clean, intact fat cells is what gets injected.
The purified fat is then injected through small incisions around the buttocks, with most of it going into the upper region for a lifted, rounded shape. The fat is placed into the subcutaneous tissue, the layer of fat that naturally sits just beneath your skin and above the muscle. On average, surgeons inject around 600cc of purified fat per side, or roughly 1,200cc total.
How Much of That Fat Survives
Not all of the injected fat becomes permanent. Transplanted fat cells need about six weeks to grow new blood vessels that supply them with oxygen and nutrients. During that window, some cells don’t establish a blood supply and are reabsorbed by the body. On average, 60% to 80% of the transferred fat cells survive long-term and become a permanent part of your buttocks. This is why surgeons sometimes slightly overfill the area, anticipating some loss.
Pressure on the fat during those first six weeks can reduce survival rates. Most surgeons recommend minimal sitting during this period and may provide a special cushion for limited use. The final shape typically stabilizes after a few months once the surviving fat cells are fully integrated.
Why Injection Depth Matters for Safety
The single biggest safety concern with BBLs is where the fat is placed. If fat is accidentally injected below the muscle layer instead of into the subcutaneous tissue above it, it can enter large veins in the gluteal region and travel to the lungs. This is called a fat embolism, and it’s the primary cause of BBL-related deaths. A 2018 advisory from the American Society of Plastic Surgeons estimated the mortality rate at as high as 1 in 3,000, making it the deadliest cosmetic surgery at the time.
Current safety guidelines from organizations including the New York State Department of Health are strict: all fat injections should go exclusively into the subcutaneous space and never cross the fascia (the tough membrane covering the gluteal muscle). Ultrasound guidance is recommended throughout the procedure so the surgeon can visually confirm the cannula stays above the muscle. If the desired result requires more fat than the subcutaneous layer can hold, guidelines recommend staging the procedure across multiple sessions rather than injecting deeper.
Silicone Butt Implants
Butt implants are a different category entirely. The only gluteal implants approved by the FDA in the United States are made of solid silicone rubber, not the cohesive gel used in breast implants. These semi-solid silicone implants are designed to withstand the constant pressure of sitting and daily movement without rupturing or leaking. They’re placed surgically beneath the gluteal muscle.
Implants provide more projection and volume per cc than fat transfer, which makes them an option for people who don’t have enough body fat for a traditional BBL. Because they’re solid rather than gel-filled, they’re considered permanent and don’t carry the risk of rupture and silicone leakage that gel implants would.
Non-Surgical “Liquid BBL” Materials
A so-called liquid BBL skips surgery altogether and uses injectable fillers to add volume. The most common FDA-approved product used for this purpose contains microparticles of poly-L-lactic acid, a biodegradable synthetic material. It’s injected into the deep layers of skin where collagen naturally exists. The tiny particles initially fill the area, then gradually break down over time. As they dissolve, the body produces new collagen around the injection sites, creating volume that builds over several treatment sessions.
The results from a liquid BBL are more subtle than surgical fat transfer or implants. The volume increase is modest, and multiple sessions are typically needed. The effect is also temporary, lasting one to two years before the body fully absorbs the material and new collagen production slows.