BBL Shrinking: Why It Happens and What Is Normal

Yes, a BBL shrinks after surgery, and some shrinking is expected. In the first 12 weeks the buttocks get smaller as swelling settles, and over the first 3 to 6 months your body reabsorbs around 30–50% of the transferred fat, leaving roughly 50–70% as a permanent result. What is not normal is shrinking that continues well beyond 6 months, a lopsided loss on one side, or firm, painful lumps, which can point to fat necrosis or another problem worth having checked.

This guide explains why a Brazilian butt lift gets smaller, how much gluteal fat survives, what causes a deflated BBL, how to tell normal settling from a problem, and when a second round of fat transfer is possible. If you are still in the early weeks, our week-by-week BBL recovery guide sets out what to expect at each stage.

Why Is My BBL Getting Smaller?

Two separate processes make a BBL look smaller, on different timescales.

The first is swelling. Straight after surgery, part of the size you see is grafted fat and part is fluid in the tissues. Swelling peaks around days 3 to 5 and drains away over the following weeks, so the buttocks get smaller even though the fat that will survive is still there.

The second is fat reabsorption. Transferred fat is a graft: it arrives without a blood supply and has to pick one up from the surrounding tissue within days. Cells close to a good blood supply survive and become permanent. Cells too far from one, or squeezed by pressure, die and are cleared away over the following months. This is the permanent part of BBL shrinking, and it happens to every patient to some degree.

Your surgeon plans for both by placing more fat than your final target, within safe limits, so the result after reabsorption matches the shape you discussed. Our guide to how much fat is transferred in a BBL explains how those volumes are worked out.

Will My BBL Get Smaller After 3 Weeks? Swelling in Weeks 1 to 12

Yes, most people notice a clear drop in size around weeks 2 to 4, and many describe their BBL as “deflated” or “flat” at this point. This is usually swelling leaving, not fat being lost. A typical pattern looks like this:

• Days 1 to 5: the buttocks look at their biggest. Swelling and bruising peak around days 3 to 5, and the shape can look overfilled or uneven.
• Weeks 2 to 4: swelling drains quickly and the buttocks can look noticeably smaller. The skin may also feel tight and firm, which makes the shape look less rounded than it will later.
• Weeks 6 to 8: “fluffing” begins. The skin and tissues soften and relax around the surviving fat, so the buttocks look rounder and more natural, sometimes even a little fuller than at week 4.
• Around 12 weeks: most of the swelling has gone and you can see most of your result. Fine changes in shape continue for a few more months.

Fluffing does not add fat, but softer tissue sits differently and often looks fuller. Our article on when fluffing happens after a BBL covers this stage in detail.

How Much Fat Survives After a BBL?

At Centre for Surgery, surgeons plan on around 50–70% of the transferred fat surviving, with 30–50% reabsorbed. Studies that measure the buttocks with imaging, rather than by eye, support a figure in this range.

• 3D imaging: in a 2024 prospective study using 3D imaging and ultrasound, published in the Journal of Plastic, Reconstructive and Aesthetic Surgery ↗, 35 women had ultrasound-assisted fat grafting into the layer under the skin only. Fat retention measured on 3D scans was 77.9% at 3 months and 64.7% at 6 months^[1].
• Ultrasound thickness at 12 months: a 2019 prospective ultrasound study of 50 women in Plastic and Reconstructive Surgery ↗ found the fat layer of the buttocks was 56.5% thicker straight after surgery. By 12 months it had fallen back by an average of 18.2% (range 6.8% to 24.8%), leaving a lasting increase^[2].
• MRI: an earlier case series that followed patients with MRI estimated a loss of about 20% of the augmentation effect in the first 4 months^[3]. That series injected some fat into the muscle, a technique that is no longer considered safe.

Most of the measurable loss happens in the first 6 months, and results vary between people: in the 12-month study, the fall in thickness ranged from under 7% to almost 25%. No surgeon can predict your exact retention, which is why a realistic plan allows for loss and, for some people, a second session.

When Will My BBL Stop Shrinking?

For most people, BBL shrinking slows considerably by 3 months and stops between 3 and 6 months. By about 6 months, the fat cells that have survived have established their own blood supply. From then on they behave like the fat elsewhere on your body: they are permanent, but they get bigger or smaller with your weight.

Swelling can linger longer in the donor areas, particularly after 360 liposuction, so your waist may keep slimming after the buttocks have settled, making them look relatively fuller at 6 months than at 3.

Tap to reveal

Real Centre for Surgery patient, photographed at least six months after BBL surgery.

Settled results are best judged from 6 months onwards. You can see more real results in our BBL before and after photos.

Why Is My BBL Shrinking Too Much? Common Causes

Several factors can push fat loss beyond the expected 30–50%. Some are in your control during recovery; others depend on technique or anatomy.

Fat Necrosis and Oil Cysts

Fat necrosis is what happens when a cluster of grafted fat cells dies but is not cleared away neatly. It can leave firm, sometimes tender lumps under the skin. When the dead fat breaks down into liquid oil walled off by scar tissue, it forms an oil cyst, which feels like a smooth, rubbery lump. Both mean less living fat in that area, so they can show as flattening, a dent or asymmetry rather than an even loss of size.

It is more likely when a lot of fat is placed in one spot; spreading fat in fine layers lowers the risk. A 2025 systematic review and meta-analysis of 22,151 patients in Plastic and Reconstructive Surgery ↗ reported contour irregularities in 2.29% of gluteal fat grafting cases and seromas (fluid collections) in 2.03%, with the lowest complication rates when fat was placed under the skin only and ultrasound guidance was used^[4]. A separate meta-analysis of more than 6,000 ultrasound-guided cases found fat necrosis in 0.09 per 100 patients^[5].

Small areas of fat necrosis often soften over months. Larger lumps or oil cysts may need draining or removal. Our article on fat necrosis after BBL explains the signs and treatments.

Sitting Too Early

Pressure is one of the most common reasons a BBL loses more volume than planned. In the first weeks the grafted fat is relying on tiny new blood vessels growing in from the surrounding tissue. Sitting directly on the buttocks compresses the graft and can starve it of oxygen and nutrients, so more cells die.

At Centre for Surgery, patients are advised not to sit directly on their buttocks for 2 weeks. If sitting cannot be avoided, for example in a car, a BBL cushion that takes the weight on the backs of the thighs is used; toilet visits are kept brief, leaning forward. From week 3 you can usually sit normally for short spells and build up from there. You should also sleep on your front or side, not your back, for the first 2 weeks. Our guide on when you can sit after a BBL gives practical tips for the first weeks.

Smoking and Vaping

Nicotine narrows blood vessels and smoke reduces the oxygen carried in the blood, both of which work against a graft that is trying to establish a new blood supply. In an experimental study in rats, fat grafts exposed to cigarette smoke lost more weight and showed more scarring than grafts in unexposed animals^[6]. Clinical experience in people points the same way: fat survival falls in smokers.

That is why Centre for Surgery asks patients to stop smoking and all nicotine products, including vapes, patches and gum, for 4 weeks before and 4 weeks after a BBL. If you start again early, you may lose more of your result.

How the Fat Is Harvested and Placed

Technique affects how many fat cells survive. Fat harvested roughly or left contaminated with blood and oil is damaged before it is placed, and fat injected in large clumps is more likely to die in the centre.

At Centre for Surgery, fat is harvested by power-assisted liposuction (PAL) or VASER and placed only in the subcutaneous layer above the gluteal muscle, never into or beneath it, using a blunt cannula and expansion vibration lipofilling (EVL). Real-time ultrasound guidance is used on every BBL so the surgeon can see the cannula tip throughout. A 2019 cadaver study found that fat placed above the muscle fascia stayed in the layer under the skin, and its authors proposed that all injections should be made exclusively into that layer^[7]. Our guide to ultrasound-guided BBL explains why this matters for safety.

Your Anatomy and Skin Quality

Your own tissues also play a part. Firm, elastic skin holds projection better than loose or stretched skin. The shape of your pelvis limits how much projection is possible however much fat is placed. Areas with scarring from previous surgery or injections have a poorer blood supply, so fat survives less well there. People with very little spare fat may not be able to have enough transferred in one session to allow for reabsorption, and your surgeon will tell you at consultation if this applies to you.

Can You Lose Your BBL If You Lose Weight?

You will not lose your BBL completely, but it will get smaller if you lose a significant amount of weight. Once settled, grafted fat cells behave like the rest of your fat. When you lose weight, every fat cell in your body shrinks, including those in your buttocks. The number of transferred cells stays the same, so the shape usually remains, just with less volume.

This is why Centre for Surgery asks for your weight to be stable for at least 3 months before a BBL (6 to 12 months after major weight loss), and why staying close to your surgery weight is the most useful thing you can do to protect your result. Large weight swings can also stretch the skin. Our article on what happens if you gain weight after a BBL covers the opposite situation.

GLP-1 Weight-Loss Medication After a BBL

GLP-1 weight-loss medicines (the class of weekly injections now widely used for obesity and type 2 diabetes) can cause rapid and substantial weight loss, and grafted fat shrinks along with the rest. A 2026 scoping review in the Aesthetic Surgery Journal found several ways in which this class of medicine could, in theory, work against a fat graft, such as increasing the breakdown of fat. It also found that no study has yet directly measured fat graft results in people taking them, so its suggestions are a basis for research rather than firm guidance^[8].

In practice, tell your surgeon at consultation if you are taking, have recently stopped or are planning to start a GLP-1 medicine. Your weight should be stable before surgery, and starting one soon after a BBL is likely to reduce your result. If you are prescribed one later for medical reasons, follow your prescriber’s advice and expect some change in buttock size as you lose weight.

What Happens to a BBL as You Age?

The fat that survives a BBL is long-lasting, but your body keeps ageing around it. Skin loses collagen and elasticity, the buttocks can sit a little lower, and fat distribution changes, particularly around the menopause, much as the buttocks would have changed without surgery. Weight changes, pregnancy and reduced muscle tone add to this, while exercise that strengthens the gluteal muscles helps support the shape once you are cleared for it at 6 weeks. Our guide on BBL after 10 years looks at long-term changes, including when a buttock lift to remove loose skin may suit better than more fat.

Deflated BBL: Can a BBL Fail or Disappear Completely?

A BBL that disappears completely is rare. A “failed BBL” or “disappeared” BBL is usually one of three things:

• Expectations set by the swollen early result. If you expected to keep the week-1 size, a normal settled result can feel like a failure.
• Higher than average reabsorption. Smoking, early sitting, a small amount of transferred fat or poor graft handling can leave much less fat than planned.
• Complications. Fat necrosis, infection or a fluid collection can destroy part of the graft and cause dents or asymmetry.

Very occasionally there is so little donor fat that the improvement after reabsorption is modest, and your surgeon should tell you at consultation if your expected result is limited in this way.

Is It Normal Settling or a Problem? How to Tell

Most BBL shrinking is normal, but some signs need a review. This comparison can help you decide whether to wait or get in touch.

• Usually normal: both sides getting smaller evenly over weeks 1 to 12; buttocks looking flat or square around weeks 2 to 4, then softening from 6 to 8 weeks; mild firmness or small, soft lumpy areas in the first months; slight differences between sides that are improving.
• Worth a review: one side shrinking clearly more than the other; a firm lump that keeps growing or does not soften after 3 months; a dent appearing in a previously smooth area; continued obvious shrinking after 6 months without weight loss.
• Contact the clinic urgently (or NHS 111 out of hours): a red, hot, increasingly painful or swollen area, discharge or an unpleasant smell from a wound, a fever, or pain and swelling in a calf. These can be signs of infection, fat necrosis breaking down or a blood clot.
• Call 999: breathlessness, chest pain or coughing blood.

Centre for Surgery patients have their surgeon’s direct number for the first 24 hours, then the clinic on 020 7993 4849 (9am to 6pm, Monday to Saturday). Reviews at 3 and 6 months are available, and if you are worried about your shape before then you can be seen sooner for an assessment. Photos from the same angles every few weeks are easier to judge than the mirror.

How Can I Stop My BBL From Shrinking?

You cannot stop the expected 30–50% reabsorption, but you can avoid adding to it:

• Keep pressure off your buttocks for 2 weeks, using a BBL cushion when sitting is unavoidable and sleeping on your front or side.
• Stay off nicotine, including vapes, for 4 weeks before and after surgery.
• Wear your compression garment day and night for 6 weeks. It covers the donor areas and leaves the buttocks free.
• Eat well and do not diet in recovery. Enough protein and calories support healing; cutting calories hard shrinks the graft, but overeating does not make more fat survive.
• Build exercise up gradually: walking from day 1, light cardio such as walking (not cycling) from week 3, and full exercise including weights from 6 weeks.
• Keep your weight stable once you have healed.

Can You Have a Second Round of Fat Transfer? Revision BBL

Yes. If your BBL has settled smaller than you hoped, a second round of fat transfer, often called a revision BBL or BBL top-up, can add volume or correct dents and asymmetry. It is usually considered at least 6 months after the first operation, once swelling has gone and the surviving fat is stable, so your surgeon can see exactly what is there. At Centre for Surgery, revision is discussed at the 6-month review.

A second round needs enough donor fat, and areas treated the first time often have less left, so other donor areas may be used. Scar tissue can make grafting slightly less predictable, and the same aftercare rules apply. If the result is too large or uneven rather than too small, liposuction can reduce areas, although a BBL cannot be fully reversed. Our guides to revision BBL and BBL costs in London cover the options and what affects the price.

Frequently Asked Questions

Brazilian Butt Lift in London

BBL surgery at Centre for Surgery is performed by GMC-registered surgeons at our CQC-regulated Baker Street hospital, rated Good overall by the CQC. Fat is placed only in the layer above the gluteal muscle under real-time ultrasound guidance on every BBL, harvested by PAL or VASER liposuction, and the operation is carried out as a day case under TIVA (total intravenous anaesthesia). Your surgeon will plan for reabsorption and review your result at 6 weeks, with reviews at 3 and 6 months available. The consultant who assesses you is the consultant who performs your surgery, and we recommend a two-week cooling-off period before you go ahead. Your initial consultation fee is redeemable against the cost of surgery if you go ahead. Finance isn’t available for BBL at Centre for Surgery, so the procedure is self-funded.

Phone: 020 7993 4849 | Address: 95–97 Baker Street, Marylebone, London W1U 6RN
Contact us to schedule a consultation

References

1. Wang B, He P, Zhao R. B-ultrasound-assisted gluteal fat grafting in Asians: a prospective study of quantitative results from three-dimensional imaging and B-ultrasound analysis. Journal of Plastic, Reconstructive and Aesthetic Surgery 2024;94:12–19. doi:10.1016/j.bjps.2024.04.035 ↗
2. Cansancao AL, Condé-Green A, David JA, Vidigal RA. Subcutaneous-only gluteal fat grafting: a prospective study of the long-term results with ultrasound analysis. Plastic and Reconstructive Surgery 2019;143(2):447–451. doi:10.1097/PRS.0000000000005203 ↗
3. Murillo WL. Buttock augmentation: case studies of fat injection monitored by magnetic resonance imaging. Plastic and Reconstructive Surgery 2004;114(6):1606–1614. doi:10.1097/01.prs.0000138760.29273.5d ↗
4. Elsaftawy A, Bonczar M, Jagosz M, et al. Gluteal augmentation with fat grafting: a systematic review and meta-analysis of complications and procedural factors. Plastic and Reconstructive Surgery 2025;157(3):381e–393e. doi:10.1097/PRS.0000000000012437 ↗
5. Milani Reis A, Roca Mora MM, Bicudo Bregion P, et al. Ultrasound-guided gluteal fat grafting: what is the evidence? A systematic review and meta-analysis. Aesthetic Surgery Journal 2025;46(1):57–62. doi:10.1093/asj/sjaf059 ↗
6. Ercan A, Baghaki S, Suleymanov S, et al. Effects of cigarette smoke on fat graft survival in an experimental rat model. Aesthetic Plastic Surgery 2019;43(3):815–825. doi:10.1007/s00266-019-01327-3 ↗
7. Wall S, Delvecchio D, Teitelbaum S, et al. Subcutaneous migration: a dynamic anatomical study of gluteal fat grafting. Plastic and Reconstructive Surgery 2019;143(5):1343–1351. doi:10.1097/PRS.0000000000005521 ↗
8. Chalhoub X, Ng ZY. Do glucagon-like peptide-1 receptor agonists sabotage fat grafts? A scoping review of glucagon-like peptide-1 receptor agonist effects on adipocyte biology and implications for autologous fat transfer. Aesthetic Surgery Journal 2026;46(11):1214–1220. doi:10.1093/asj/sjag108 ↗

Related Articles

• When Does Fluffing Happen After BBL?
• Fat Necrosis after BBL – Causes & Solutions
• Revision BBL
• How Long Do BBL Results Last?