A flat butt has little projection because there is little fat over the gluteal muscle and the pelvis and hips are shaped so that nothing rounds it out; a saggy butt has enough tissue, but the skin has lost its elasticity and the fat has dropped. Both can be improved, and squats fix neither: a Brazilian butt lift adds the missing fat layer with your own fat and restores the lift wherever the skin still has recoil. When the skin itself has given way, only removing skin helps, and that is a buttock lift, an operation Dr. Cat does not perform. Telling you which of the two your anatomy needs is the first thing she works out.
What Is Happening
The shape of your backside comes from three layers: the gluteal muscle, the fat sitting over it, and the bone structure beneath, with the way your waist meets your hips. Projection and roundness are driven mostly by the fat layer and your skeletal proportions, not the muscle alone, so a frame that is genetically flat, narrow-hipped, or carries little fat over the buttocks reads as flat, or as a pancake butt, even on a fit body. A wide waist above little fat makes the same buttock look flatter still, which is why the waist-to-hip ratio matters as much as the buttock itself.
Why It Happens
Genetics come first: your inherited bone structure, hip width, and where your body stores fat. Some people carry little fat over the buttocks, so there is nothing to create projection, and weight loss flattens the area further as volume disappears. Pregnancy changes the picture too: the weight gain and loss, the shift in where fat is stored, and months of sitting and reduced training leave many mothers with a butt that is both flatter and lower than before. Then age: the skin loses elasticity, muscle mass declines a little each decade, and the fat pad slides down the back of the thigh, which turns a full buttock into a saggy one.
Sitting, Age and the Flat Bum
Sitting does not melt fat, but hours of it each day switch the gluteal muscles off; physiotherapists call the result gluteal amnesia or dead butt syndrome, a weak, underused muscle that gives the fat layer less to sit on and can bring hip and lower back pain with it. Training wakes the muscle up and firms the base. Age works the other way: with each decade the skin thins, elastic fibers stretch and the fat pad descends, so most bums do get flatter and lower with time.
Flat Versus Saggy: The Difference Decides the Operation
A flat butt is a volume problem. A saggy butt is a skin problem, sometimes with a volume problem underneath it. A BBL adds volume and shape; it is not a skin-removal lift, and when the main issue is loose skin, for instance after major weight loss, fat placed under it lifts a little and then the skin drapes again. In that case the plain answer is skin removal, a buttock lift, which takes the loose skin between the lower back and the upper buttock through a scar across the top. Dr. Cat does not perform buttock lifts, and she will tell you at the consultation if that is what your anatomy needs rather than sell you a fat transfer the skin would swallow. Most saggy butts we see are not that far along: the skin still has recoil, and a BBL that fills the upper and outer buttock restores the lift. If loose thigh skin is part of the picture, a thigh lift can be staged with it.
Why Squats Alone Cannot Add Shape
Squats and glute work build the muscle, which helps, but they cannot add the fat layer that creates a soft, rounded projection, and they cannot change your bone structure or move fat from your waist to your hips. That is why someone can train hard and still feel flat, and why a training program adds firmness over months and shape only modestly. A Brazilian butt lift takes a different approach: it relocates your own fat to build shape where exercise cannot.
The Options
Brazilian Butt Lift (Fat Transfer)
A BBL is two procedures in one operation: liposuction 360 of the back, waist and abdomen to harvest fat and narrow the waist, then transfer of the washed fat into the buttocks and hips. Dr. Cat describes it as working with clay: liposuction thins certain areas, and the fat transfer adds to the buttock and shapes it. She places the fat at multiple depths and angles through incisions under 4 mm, under general anesthesia, over four to seven hours depending on the areas. In Dr. Cat's experience more than 80 to 90 percent of the transferred fat survives, which is why her patients rarely need a second round. Two rules are fixed: no direct sitting on the buttocks for 6 weeks, with a pillow that shifts pressure to the thighs, and a BBL is never done on the same day as a tummy tuck or a breast augmentation; those combinations are staged on separate days, because the two recoveries need pressure kept off opposite sides of the body. Read about a Brazilian butt lift in Beverly Hills for the full procedure, or our guide to what a BBL is.
Skinny BBL for Slim Patients
If you are lean, the question is donor fat, not desire. A skinny BBL harvests from the flanks, lower back and thighs of a slim frame and transfers a smaller volume to shape rather than enlarge; the result is a rounder, lifted profile in proportion to a small body, not a dramatic one. The fat survival and no-sitting rules are the same.
Butt Implants
Silicone implants placed in or over the gluteal muscle add projection without donor fat, which is why some surgeons offer them to very lean patients. They bring implant problems with them: shifting, rupture, capsular contracture, a firm feel and a visible edge on a thin frame. Dr. Cat does not place buttock implants. Fat is her only approach because it slims the donor areas while it shapes the buttock with your own tissue, and once it has taken it is part of you, with nothing to shift, harden, rupture or replace; a patient without enough fat for a BBL is told so at the consultation, not offered an implant. Our post on butt implants vs BBL sets the two side by side.
Butt Injections and Fillers
Injectable collagen stimulators such as Sculptra add modest volume over several sessions and fade within a year or two. Dr. Cat does not inject Sculptra or any filler into the buttocks: the volume is small, temporary and paid for again each time it fades, and no injection can narrow the waist that frames the buttock, which is half of what a BBL does. What injections are not is a shortcut: injections of silicone or other unapproved substances, sold cheaply by unlicensed providers, have caused tissue death, embolism and deaths. Our post on butt injections vs BBL covers what is legitimate.
If You Had a BBL Elsewhere
Lumps, asymmetry, a shelf where the fat sits, or a result that shrank can often be corrected; read about a botched BBL. And hip dips, the inward curve between the hip bone and the thigh, are a skeletal contour with their own page; fat transfer fills them, often in the same operation as a BBL.
What Dr. Cat Looks For at the Consultation
She assesses your frame, the fat available to harvest and the shape you want, asks you to bring photos of buttocks you like, and then tells you what a BBL can and cannot achieve for your anatomy. One warning she gives every patient: many goal photos on social media, including some posted by surgeons and clinics, are edited, and she will say so when the shape in the photo is not obtainable. Candidates should be close to a stable goal weight and hold it afterward, and she will not proceed if the fat is not there. The consultation fee is $500, credited toward surgery; the discovery call before it is free.
Before and After
Study the back and three-quarter views in our BBL before and after photos: the change in the waist is half of the result.
Recovery in Brief
You spend the first night at an aftercare facility with nursing, most patients manage with Tylenol, you are back at desk work in about a week and at most normal activities by four weeks, you wear a compression garment for six weeks, and swelling has largely settled by the sixth week; the final shape shows at three to six months, once the fat that survived has its own blood supply. The week-by-week version is in our guide to BBL recovery.
Cost in One Line
Dr. Cat's surgeon's fee for liposuction with fat transfer to the buttocks is $56,500 to $63,500; the operating room and anesthesia are quoted at your consultation, and our BBL pricing guide explains what the quote includes and what moves it. Surgeon's fees are typical ranges: a more complex case can cost more, and your fee is set at your consultation and is final only in your written quote.
Frequently Asked Questions About a Flat or Saggy Butt
How to fix a flat butt?
Train the glutes if you want firmness, and accept that shape comes from fat and bone. If your weight is stable and you have donor fat, a Brazilian butt lift moves your own fat to the buttocks and hips and narrows the waist at the same time. Dr. Cat does not place buttock implants or inject fillers; very lean patients are assessed for a skinny BBL.
How long does it take to get rid of a flat bum?
With training, expect firmer glutes in a few months and little change in shape. With a BBL, the new shape is visible immediately, swelling settles over six weeks, and the final result shows at three to six months once the transferred fat has its own blood supply.
What are the causes of flat buttocks?
Genetics set the bone structure, hip width and where fat is stored; little fat over the gluteal muscle reads as flat. Weight loss, pregnancy, long hours of sitting that switch the glutes off, and age, which thins the skin and lets the fat pad descend, all add to it.
Does your bum get flatter with age?
Usually, yes. Skin loses elasticity, muscle mass declines a little each decade, and the fat pad slides down the back of the thigh, so the buttock looks flatter and lower. Fat transfer restores volume where the skin still has recoil; skin that has given way needs a skin-removal lift, which Dr. Cat does not perform.
Why are my buttocks flat even though I do squats?
Squats build the gluteal muscle, but the rounded shape and projection of the buttocks come largely from fat and bone structure sitting on top of that muscle. Exercise cannot add that fat layer or improve your waist-to-hip curve, so a genetically flat shape often stays flat.
Is a Brazilian Butt Lift actually a 'lift'?
Not in the skin-removal sense. A BBL adds shape and projection by transferring your own purified fat; it is a fat-transfer augmentation, not a skin-excision lift. The lift refers to the rounder, higher appearance, not to cutting away skin.
Do I need enough body fat for a BBL?
Yes. A BBL uses your own fat, harvested by liposuction from areas like the waist and back, so you need enough donor fat. Patients should be close to a stable goal weight and keep it stable afterward; slim patients may be candidates for a skinny BBL.
Talk to Dr. Cat About Your Shape
Start with a free discovery call: tell us what bothers you and whether you have had surgery before, and we will tell you whether a consultation makes sense, or call (310) 858-8808. Before you visit, look through the BBL before and after photos and read the full Brazilian butt lift in Beverly Hills page.
Medically reviewed by Dr. Cat Begovic, MD, FACS, board-certified plastic surgeon. Last reviewed September 2026.