Breasts After Weight Loss: Why Your Bra Size Changes (and Your Cup Letter Might Not)

Over the past 12-18 months, our Bra Fitting suites in Melbourne have seen a large increase in the number of women presenting for fittings after substantial weight loss. Many, but certainly not all, using GLP-1 medications. Whatever the reason for rapid and substantial weight loss, there can be a big shift for our bust size and density. And these fittings do require some extra experience and great quality product to have the customer leaving both well supported and feeling really great about themselves. 

Another interesting anecdote, which is often a real struggle for people in the change room is that after extreme weight loss our cup size won't always change. And not because our breasts haven't changed. But because the cup letters are relative to the band size, not a fixed volume. 

Why Your Cup Size Can Stay the Same After Weight Loss

Have you ever heard of sister sizing?  Sister sizes are two bra sizes that offer the same volume of cups, but different band sizes. If you go down one band size and up one letter in cup size, you maintain the same volume.

Let's use this example... Someone was a size 16G pre weight loss. They lose 3 dress sizes, or 18kg. 
They get fitted post weight loss and are sized as a 10G. 
A size 10G is actually 3 whole cup sizes in volume smaller than a 16G. But yet the cup size on the tag sounds so similar that it leaves them disheartened. 

Because their breasts decreased in size in the same proportion to the rest of your body, then it's not farfetched at all to have the cup size remain consist. 

The key thing to focus on is that they have actually gone down 3 cup sizes. Which is a huge reduction by most peoples standards. 

The other thing to be aware of is that breast are also a mix of fatty and glandular tissue, so it's really common for them to actually lose less volume than the rest of your body. For this reason, we sometimes see cup sizes go up. To use the example above, if this person had lost less breast volume comparatively to the rest of her body then we could even expect her to present as a 10GG. Sounds bigger?! But in reality this customer has actually gone down 3 dress sizes and 2 cup sizes. 

💡 Didn't know that a 10G is 3 cup sizes smaller than a 16G? You really need to watch this video 👇🏽

What Actually Changes in Your Breasts After Weight Loss

As I eluded to above, breasts are not simply made up of fat. They are a combination of fatty tissue, glandular tissue and connective tissue. The theory is that it's the fatty tissue that largely determines size.

Breasts vary greatly from woman to woman. A study has shown that breasts can range from 2-78% of fatty tissue. 

This is why some women can lose a lot of cup volume during weight loss and other may only lose a bit - because it all depends on the ratio of fatty tissue, to glandular tissue to connective tissue that they started with. 

And it's not just volume reduction that changes. After substantial weight loss women can expect to lose fullness towards the upper-cup. This is aligned with a 2010 study of 132 patients (Rinker et al., Annals of Plastic Surgery) found significant weight loss was a risk factor for breast ptosis (sagging), alongside age, BMI, cup size, pregnancies and smoking.

We've heard the new buzz word (not coming from the scientific community, but rather from customers themselves) "Ozempic Breasts". Now this isn't always specifically in reference to weight gain from taking Ozempic, but more so in reference to just breasts in general after weight loss. It's nice to see the internet talking about this as a common and relatable issue these days.

Signs Your Bra No Longer Fits After Weight Loss

• Gaping at the top of the cups: There has been a loss of upper fullness, or the cup style no longer matches your shape. Remember, this won't always always mean a smaller cup letter.

• Band riding up at the back: The band is now too loose. This is the first thing to change. As this is the "engine room" of the support, customers will feel instantly better when this is fixed. This almost always means we need to reduce the band size. 

• Straps slipping or digging: This is a result of the band no longer doing the support work, the secondary means of the support (the straps) kick in to over drive creating a pulling and tugging sensation. Straps can also slip when the bra band is too loose as the straps aren't going to sit in the correct place on your smaller back. 

• Wires sitting off the breast, or on breast tissue: Again, after weight loss this is usually because the band size is too big and the band can no longer clutch on to the correct part of your ribcage.  

• Band suddenly feeling tighter: This is actually typically because there is less fatty tissue and the bra band can be more noticeable, women can confuse this for feeling tighter, when really it's just a sensation they aren't used to feeling against their ribcage. 

What to Look for in a Bra After Weight Loss

✅ Soft flexible upper cups eg a lace with some stretch. 

✅ Cut-and-sewn bras (bras with seams) are typically better than t-shirt lined bras

✅ Plunge styles may be an option for shapes with less upper colume

✅ For those seeking a t-shirt bra, opt for a shallow cup with an overlay material. Like this one.

✅ A strong, well fitted ribcage band. Opt for styles that have wider ribcage bands to smooth out softer lines across the back. 

✅ A compressive Sports Bra often works best with a loss of breast density. 


❌ Deep, moulded cup bras

❌ Ultra soft, stretchy materials

❌ No adjustability

How Often to Get Refitted During Weight Loss

I wish there was a magic number or time frame for us to give you, but unfortunetly there isn't. Keeping in mind that a 3kg weight change can change your bra size, that would obviously be a bit too much to keep up with during a substantial weight loss journey. 

I'd recommend getting a fitting as soon as your bras are holding you back, or at minimum every 10-12kg weight loss.

When customers present during a weight loss phase we can be strategic about which styles we chose, and avoid, and also how we are choosing to fit them in order to get the best lifespan out of their product. 

An experienced Bra Fitter with access to a broad range of quality product, like us at She Science, will make all the difference in having you get the best value out of your bras during this time. You can book a Bra Fitting with us in Melbourne online. 

FAQ's for boobs after weight loss

Do your boobs get smaller after weight loss?

As breasts are partially made up of fatty tissue, yes they are likely to get smaller after weight loss. But if someones breasts only have a small percentage of fatty tissue to start with then they may also experience little to no reduction in size.  

Why is my cup size the same after losing weight?

Cup letters are relative to band size. If your band dropped, the same letter now holds less volume. This is sister sizing. So if you have lost weight proportionately across your body then you can actually expect your cup size to remain the same. Above, I used an example of a starting size of 16G and a post weight loss size of 10G sounding similar, but actually being 3 cup sizes smaller post shape change.  

What are ozempic breasts?

This is a term coined by the internet to describe post dramatic weight loss breasts. It is intended to refer to breasts that have changed in density and size dramatically. 

When should I buy new bras after weight loss?

Get fitted as soon as you feel like the ribcage band is too loose. This is where the support comes from. Having this fitted well will optimise how you feel in your bra, and what your bra can do to support your breasts. 

She Science, our Specialty Bra Store offers cup sizes A - K and band sizes 6 - 24. We work with 22 industry leading brands from all over the world. Our comprehensive Sports and Everyday Bra fitting service is available by appointment, out of our fitting suite in Hawthorn, Melbourne (Australia). Come on in and we'll find you your best match taking in to account your size, shape, activity demands and personal style preferences. Our team of experienced bra fitters would love to meet you.