The shape of your bottom cannot tell you anything about your hormones, whatever recent social media posts claim. The only way to find out your levels of cortisol, oestrogen or anything else is a blood test.
Author
- Adam Taylor
Professor of Anatomy, Lancaster University
A heart-shaped bottom, influencers say , signals healthy oestrogen , while an H shape means too much cortisol. In reality, buttock shape doesn’t reflect your circulating hormone levels from day to day, week to week or month to month.
So what decides your shape? Mostly your genes. They give you your skeletal structure and your muscle size and structure. And in the buttocks and everywhere else, how much fat you are likely to carry there.
The shape of the pelvis varies between people. In obstetrics, four traditional categories describe the internal bony structure of the pelvis, which is also the shape of the opening through which a baby passes during birth: gynaecoid, android, anthropoid and platypelloid.
Gynaecoid is the most common in females and the most favourable for a vaginal birth. Android is narrower and close to the shape of a male pelvis. Anthropoid is narrower from side to side but longer from front to back, while platypelloid is the reverse. You cannot tell which type a woman has by looking at the skin over her pelvis or buttocks.
This bony framework is what your muscles attach to. It also decides the spaces around them that get filled in with fat . Almost all the features you can see or measure on your hips and buttocks come from this bony architecture. In other words, your skeleton sets the starting point.
Over the top sits the skin, which shows the contours of the tissue underneath. This gives rise to the buttock types often described by plastic surgeons: H-, A-, O- and inverted V-shaped.
The crease beneath each buttock, known as the infragluteal fold, forms where the skin and underlying tissues are attached to deeper structures. These attachments help determine the position and shape of the lower edge of the buttocks.
Muscle also contributes to the shape of the buttocks, and it’s the part you can change most easily. Some people who lose a substantial amount of weight while taking GLP-1 medicines develop what is known as “Ozempic butt” , in which the buttocks appear flatter or more sagging. This can reflect the loss of fat and muscle , as well as changes in the skin.
Changes over a lifetime
Buttock shape does change later in life for women. This is typically linked to the menopause, when levels of oestrogen begin to decline . As oestrogen falls, fat is deposited towards the abdomen rather than under the skin around the hips and buttocks, as it is before menopause. So hormones do shape where fat goes, but only as part of a slow, long-term change.
This does not mean a woman will move from one buttock shape to another – genetics do not change. Any short-term change across the menstrual cycle, driven by hormone rhythms, is likely to be unnoticeable. It would be down to fluid retention , which happens across the whole body rather than in one specific region.
A woman’s skeleton also alters with ageing around the menopause, influenced by muscle loss , changing hormones and looser connective tissues . But this is a long-term process.
Stress will not change things either. A particularly stressful period will shift your cortisol levels, but this will not make fat move from your bum to your tum. Stress might cause more fat to be stored in one area, but it is well recognised that our genetics determine where our fat is stored.
Hip dips
This is not the first time social media has tried to convince people that their buttock shape can be changed. Hip dips have also been suggested as something you can modify, but like the buttocks, their shape is mainly influenced by genetics, which drive our skeletal and muscular structure.
Changing anything so reliant on genetics often takes surgery . And in this part of the body, certain operations carry some of the highest risks of death from cosmetic surgery.
Your buttock shape reflects a combination of inherited anatomy, fat and muscle. Hormones can influence how that shape changes over time, particularly around menopause, but appearance alone cannot tell you whether your hormone levels are normal.
