In this guide12 sections
- Key Points
- Why Do the Buttocks Go Flat After Weight Loss?
- What Is a Flap Buttock Augmentation?
- Flap vs BBL vs Buttock Implants After Weight Loss
- How Much Shape Does a Flap Add?
- Who Is a Good Candidate?
- What Happens During Surgery?
- Recovery After Flap Buttock Augmentation
- Risks and Complications
- How Much Does Flap Buttock Augmentation Cost?
- Frequently Asked Questions
- References
Key Points
- After major weight loss the buttocks often lose volume and drop, and a buttock lift or lower body lift can leave them flatter still.
- A flap buttock augmentation, also called autologous gluteal augmentation or auto-augmentation, keeps the spare tissue above the buttocks on its own blood supply and folds it underneath to add shape.
- It uses your own tissue, so there is no implant and no fat injection, and it is done through the same incision as the lift.
- Research suggests flaps mainly prevent the flattening a lift causes rather than adding a lot of projection. Implants add more, and fat transfer is another option.
- It suits people with flat, descended buttocks and enough spare tissue on the lower back, whose weight has been stable for at least six months, ideally 12.
A flat bum after weight loss is a common concern, and it often becomes more noticeable once loose skin has been removed. A buttock lift, or the back stage of a lower body lift, lifts sagging skin, but it also removes tissue from an area that has already lost volume. Flap buttock augmentation was developed to deal with this. Instead of throwing away the spare tissue above the buttocks, the surgeon uses it to rebuild shape.
At Centre for Surgery, our GMC-registered plastic surgeons perform flap buttock augmentation alongside buttock lifts and lower body lifts at our Baker Street hospital in London, under TIVA (total intravenous anaesthesia). This guide explains how the technique works, who it suits, how it compares with a Brazilian butt lift (BBL) and buttock implants, and what recovery involves.
Why Do the Buttocks Go Flat After Weight Loss?
The buttocks are one of the areas where fat is lost early and in large amounts. After major weight loss, whether through bariatric surgery, medication or diet, many people find their buttocks have lost volume, the skin has stretched and the whole buttock has descended, often with folds of loose skin above it on the lower back.
Removing the loose skin with a buttock lift or lower body lift tightens and raises the area, but it does not put back lost volume. In some patients the tightening flattens the buttocks further, which can make clothes fit poorly and, for some people, makes it harder to keep trousers up. Our guide to saggy buttocks covers the causes in more detail.
What Is a Flap Buttock Augmentation?
During a buttock lift or the back stage of a lower body lift, a band of skin and fat is removed from the lower back, just above the buttocks. In a flap buttock augmentation, part of this tissue is kept attached to its own blood supply. The surface skin is removed, and the remaining fatty tissue is turned or rotated down into a pocket beneath the lifted buttock skin, where it acts as a natural filler.
Several designs exist. Some surgeons base the flap on a named blood vessel, such as the superior gluteal artery perforator, while others use broader turnover or “purse-string” flaps. In a 2007 series of 18 patients in Plastic and Reconstructive Surgery ↗, perforator flaps were moved into the lower inner part of the buttocks during lower body lifts; the auto-augmentation added about an hour to the operation, there were no complications during surgery, and patients reported clear improvement in volume and contour.[1]
You may see the procedure called autologous buttock augmentation, autologous gluteal augmentation, gluteal auto-augmentation or a flap gluteoplasty. They all describe using your own tissue, moved on its blood supply, to shape the buttocks.
Flap vs BBL vs Buttock Implants After Weight Loss
There are three main ways to add shape to the buttocks after major weight loss, and the right choice depends on how much fat you have, where it sits and what you want to achieve.
- Flap augmentation uses the spare lower back tissue removed during the lift. It needs no implant or fat injection, but it relies on having enough tissue in that area, and the amount of shape it adds is limited.
- Fat transfer (Brazilian butt lift) moves fat by liposuction from elsewhere, such as the abdomen or thighs, and injects it into the buttocks. It suits people with enough donor fat. At Centre for Surgery a BBL is performed under real-time ultrasound guidance, so fat is placed only in the layer under the skin and above the muscle, which is the key safety measure. A BBL is done as a separate operation, not in the same session as a tummy tuck or lower body lift.
- Buttock implants add a set amount of projection without needing donor fat. They carry implant-specific risks such as infection, displacement and the need for later revision.
A French study of 280 lower body lift patients ↗ used exactly this kind of algorithm: implants for people with little back fat, flaps for those with substantial lower back fat, fat grafting for those with plenty of fat elsewhere, and no augmentation where buttock shape was already good. Most patients (76%) had flaps, and adding gluteal augmentation did not increase the complication rate.[2]
How Much Shape Does a Flap Add?
It is worth having realistic expectations. A prospective study from the same Paris group measured buttock projection in 3D before surgery and six months after a lower body lift.[3] Patients who had no augmentation lost almost a centimetre of projection on average. Those who had flaps kept their projection, ending up roughly where they started, while those who had implants gained about half a centimetre. Flaps took less operating time and were less painful in the first two weeks than implants, and minor complication rates were similar.
In practice, this means a flap is better thought of as protecting and reshaping the buttocks during a lift, rather than giving a dramatically fuller bottom. If more volume is your main goal, fat transfer or implants may be discussed as a separate, later stage once you have healed. Some surgeons combine flaps with fat grafting for this reason: a 2024 series of 23 patients in the Aesthetic Surgery Journal ↗ reported very high satisfaction scores, with four small wound separations treated without further surgery.[4]
Who Is a Good Candidate?
You may be suitable for flap buttock augmentation if:
- You have flat, descended buttocks with loose skin, usually after major weight loss.
- You have a fold of spare skin and fat on the lower back that will be removed during the lift anyway.
- You are planning a buttock lift or a lower body lift.
- Your weight has been stable for at least six months, and ideally 12 after major weight loss.
- You do not smoke, or can stop all nicotine at least four weeks before and four weeks after surgery.
- You are in good general health and aged 18 or over.
It is less suitable if you have very little tissue on the lower back, or if your main aim is a large increase in buttock size. In those cases your surgeon may discuss a BBL or implants instead, usually as a separate stage.
What Happens During Surgery?
The flap is created during the buttock lift or the back stage of a lower body lift, under TIVA. Your surgeon marks the planned incision and the flap with you standing. During the operation, the skin above the buttocks is lifted, the surface skin of the flap is removed, and the flap is moved into a pocket created under the buttock skin and secured. The incision is then closed in layers along the planned line, which is usually placed to sit within underwear. Drains may be used.
At Centre for Surgery, a lower body lift is performed in two stages, at least six to twelve weeks apart. The flap augmentation is part of the back stage, which treats the lower back, buttocks and outer thighs. Our belt lipectomy guide explains the staged approach.
Recovery After Flap Buttock Augmentation
Recovery follows that of the buttock lift, with some extra care to protect the flap while it settles.
- First two weeks: avoid sitting directly on your buttocks for long periods and sleep on your front or side as advised. Gentle walking from the first day lowers the risk of blood clots.
- Compression: a compression garment is usually worn for around six weeks.
- Work: most people return to desk-based work after about two to three weeks, depending on how comfortable sitting is.
- Exercise: strenuous exercise and heavy lifting wait until at least six weeks.
Swelling settles over three to six months, and the scar continues to fade for up to a year. Our guide to body lift recovery and our advice on sleeping after body lift surgery cover the wider recovery.
Risks and Complications
The risks are those of a buttock lift, together with some specific to the flap. They include wound separation along the incision, seroma, infection, bleeding, asymmetry, changes in sensation, and, uncommonly, partial loss of the flap if its blood supply is poor, which can leave firm areas of fat necrosis. Wound problems are the most frequent issue after lower body contouring generally. Stopping smoking, a stable weight and good nutrition all lower the risk; our guide to reducing complications from skin removal surgery explains the steps.
How Much Does Flap Buttock Augmentation Cost?
Flap augmentation is priced as part of your buttock lift or lower body lift and is confirmed in writing after a face-to-face consultation. Finance is available for the buttock lift and lower body lift, subject to status; see our finance options. Finance is not available for a BBL or buttock implants.
Frequently Asked Questions
What is autologous buttock augmentation?
It means adding shape to the buttocks with your own tissue rather than an implant. In flap augmentation, the spare tissue removed from the lower back during a buttock lift is kept on its blood supply and folded beneath the buttock skin.
Why is my bum flat after weight loss?
The buttocks lose a lot of fat during major weight loss, and the skin stretches and drops. Exercise can build the gluteal muscles, but it cannot replace lost fat or remove loose skin, so many people need a lift, sometimes with augmentation.
Is a flap better than a BBL after weight loss?
Neither is better for everyone. A flap uses tissue that would otherwise be thrown away and avoids fat injection, but it adds limited volume. A BBL can add more volume if you have enough donor fat, and at Centre for Surgery it is done as a separate operation under ultrasound guidance.
Can flap augmentation be done with a lower body lift?
Yes. It is usually performed during the back stage of a lower body lift, which treats the lower back, buttocks and outer thighs.
Will the result last?
The flap is living tissue with its own blood supply, so it behaves like the rest of your body fat. It stays as long as your weight is stable, though some softening and settling over the first months is normal.
Will I have a scar?
Yes. The scar is the same as for the buttock lift, running across the lower back above the buttocks and placed to sit within underwear where possible. It fades over 12 months or more.
References
- Colwell AS, Borud LJ. Autologous gluteal augmentation after massive weight loss: aesthetic analysis and role of the superior gluteal artery perforator flap. Plast Reconstr Surg. 2007;119(1):345-356. doi:10.1097/01.prs.0000244906.48448.5d ↗
- Schmitt T, Jabbour S, Makhoul R, et al. Lower body lift in the massive weight loss patient: a new classification and algorithm for gluteal augmentation. Plast Reconstr Surg. 2018;141(3):625-636. doi:10.1097/PRS.0000000000004178 ↗
- Levan P, Bassilios Habre S. Gluteal implants versus autologous flaps in patients with postbariatric surgery weight loss: a prospective comparative study of 3-dimensional gluteal projection after lower body lift. Aesthet Surg J. 2017;37(9):1012-1021. doi:10.1093/asj/sjx033 ↗
- Alves HRN, Nicolas G. Gluteoplasty with lumbar gluteal flap associated with liposuction and fat grafting: a safe technique for massive weight loss patients. Aesthet Surg J. 2024;44(4):404-411. doi:10.1093/asj/sjad339 ↗
