Flex size bras for changing bodies

The one thing bodies are guaranteed to do is change. Luckily, bra designers are privy to those changes (heck, many of them are experiencing these same changes themselves), and they take body fluctuations into account when designing bras. If you’re wondering what kind of bra to buy to accommodate shifts in sizing, you’ve come to the right place. 

WHAT IS FLEX SIZING?

Traditional cup and band bras are custom fit to a specific bra size. If you grow a whole cup size during your cycle or due to weight gain or weight loss, it’s more challenging to wear that particular style of bra because the fit is made specifically for each size. You would most likely need to buy a new bra altogether (who has time for that) or simply suffer in a bra that doesn’t quite fit right (once again, who has the time?). That’s where flex sizing comes in.

Flex sizing refers to bras that have built-in features that allow them to flex within one or two sizes. Most commonly, you’ll see flex sizing written out like this: 34B/C. That means the bra can accommodate both a 34B and 34C cup size.

HOW ARE FLEX SIZING BRAS BUILT?

The main aspects to consider when designing flex size bras are: 1) sourcing fabrics that will be able to stretch and flex with the body, and 2) choosing specific constructions that can accommodate changes in sizing.

One construction technique is to leave a bit of extra fabric around the pads to allow for flexibility. You can also partially laminate the foam bra pad or make the pad removable so the bra cups retain the ability to stretch. Foam cups typically don't have any flexibility, so anchoring them in the bra will take away the bra's ability to stretch. Avoid bras with cups that have sewn-in or molded pads. 

As for the neckline, which is a part of the bra that is going to be flexing a lot, it’s important to choose a functional yet delicate bonding technique that won’t dig in or be too rigid.

If a flex sizing bra is well-made, it will have undergone extensive wear testing. This ensures that the bra style is durable and actually provides the benefits it claims. It can also verify whether or not the bra is flexible enough to withstand body size fluctuations. 

FEATURES TO LOOK FOR

1. Bras with adjustability. This enables you to customize your fit as needed. Typically, the features that are made to be adjustable are the straps and band.
2. Bras with small flex sizing ranges. For example, if a bra can accommodate three to four different sizes, it may result in a less tailored-feeling fit. Look for a flex size that accommodates up to two cup sizes. 
3. Partially secured or removable bra pads.
4. Flexible, stretchy fabrics in the bra cup. 

WHY DO BODIES FLUCTUATE?

Hormonal changes

For menstruating women, hormonal changes occur on a 28 day cycle. The result? You may (legitimately) feel like you’re living in a different body on a day-by-day basis. Estrogen, which peaks just before mid-cycle, can cause the breast ducts to grow in size. Progesterone, which reaches its highest level around the 21st day of a standard cycle, causes milk glands to grow. Because of these hormonal changes, your breasts may fluctuate up to a cup in size throughout the course of a month.

For postmenopausal women, the production of estrogen and progesterone decreases. As a result, milk systems shrink and breasts become softer. 

Breast ptosis 

While some sagging is genetic, a portion of ptosis can occur from excessive bounce and stretch. Over time, stretching of the skin can lengthen Cooper’s ligaments (the fibers that anchor breasts to the chest wall). When those ligaments lose their elasticity, you’re left with a sagging effect. 

Larger breasts will naturally bounce and stretch more than smaller breasts, which is in part why bigger busts are at increased risk of sagging. And, of course, breasts are at their bounciest during a high intensity workout. Investing in a properly fitting and secure sports bra is a great way to slow the effect of sagging over time. 

Lifestyle changes

Bodies naturally fluctuate in weight over the course of a lifetime for a long list of factors — some in (and many out) of our control. As weight fluctuates, breast shape and size will fluctuate too. An extreme change in weight can result in a dramatic change in cup size.