Honestly, we’ve been lied to for decades. You’ve probably heard it from your mom, a random aunt, or even a pushy sales associate at a department store: "If you don't wear a bra, they're going to hit your knees by the time you're forty." It sounds like a horror story designed to keep the lingerie industry in business. But does the science actually back that up? Does will not wearing a bra cause sagging or is it just another old wives' tale?
The truth is way messier than a simple yes or no.
Breasts are basically made of fat, glandular tissue, and these thin, internal structures called Cooper’s ligaments. Think of Cooper's ligaments like tiny, biological suspension cables. Over time, gravity, biology, and life itself act on those cables. Whether or not you've got a piece of underwire supporting them doesn't change the underlying physics as much as you might think.
The French Study That Flipped the Script
About a decade ago, a researcher named Jean-Denis Rouillon, a professor at the University of Besançon, dropped a bombshell. He spent 15 years measuring the breasts of hundreds of women. His findings? The women who didn't wear bras actually saw a 7-millimeter lift in their nipples each year compared to the bra-wearers.
Wait. What?
Rouillon’s theory was that bras are a "false necessity." He argued that if you constantly support the breasts artificially, the supporting tissues—those Cooper’s ligaments—get lazy. They atrophy. It’s like putting your arm in a cast; when you take it off, the muscle has wasted away because it hasn't had to do any work. According to his research, going braless might actually force the body to strengthen its own natural support system.
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But—and this is a huge but—Rouillon himself warned that his study didn't represent all women. Most of his subjects were young. If you've spent 30 years wearing a bra and then suddenly stop at age 50, your ligaments aren't magically going to "work out" and lift everything back up. The damage, if you want to call it that, is already done by time and genetics.
Why Sagging Actually Happens (The Real Culprits)
If it’s not the lack of a bra, what is it? Doctors call it ptosis. It’s inevitable. Almost everyone experiences it eventually.
Age and Hormones
As we get older, especially during menopause, estrogen levels drop. This changes the composition of breast tissue. You lose the dense, glandular stuff and get more fat. Fat is softer. It’s less "perky." Couple that with the natural loss of skin elasticity (the same reason we get wrinkles), and things start to shift downward.
Genetics
Check your family tree. Seriously. Your DNA dictates the strength of your skin and the density of your tissue. Some people have high-elasticity skin that bounces back; others don't. You can't out-bra your genes.
Pregnancy and Nursing
There is a massive misconception that breastfeeding causes sagging. It doesn't. Multiple studies, including a notable one published in the Aesthetic Surgery Journal, have shown that breastfeeding isn't the culprit. The culprit is the pregnancy itself. The hormonal shifts and the rapid expansion of the skin during pregnancy stretch those ligaments. Whether the baby latches on afterward doesn't change the structural integrity of the breast.
Body Mass Index (BMI)
Weight fluctuations are a big deal. If you gain weight, the skin stretches. If you lose it, that skin might not have the "snap-back" power to return to its original shape. It’s like a balloon that’s been inflated and deflated.
The Myth of the "Perky" Bra
We need to talk about what bras actually do. A bra is a garment of comfort and aesthetics. It’s not a medical device for permanent lifting. When you wear one, you’re countering gravity in that moment.
For many women, especially those with larger cup sizes, not wearing a bra is physically painful. It’s about back pain, neck strain, and skin irritation. If you have a larger chest, the weight pulls on the shoulders. In this case, a bra isn't about preventing sagging; it's about structural support for the rest of your body.
But if you’re wearing one just because you’re afraid that will not wearing a bra cause sagging, you might be stressing for no reason. There is no clinical evidence that wearing a bra 24/7—yes, even sleeping in one—prevents the natural descent of tissue over time. In fact, sleeping in a bra can sometimes impede circulation or cause skin issues if it's too tight.
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Exercise: The One Time a Bra is Non-Negotiable
While the "lazy ligament" theory might hold water for daily lounging, high-impact movement is a totally different beast. When you run or jump, your breasts move in a figure-eight pattern. They aren't just going up and down; they're moving side to side and in and out.
This vigorous movement can actually tear those Cooper’s ligaments. This is called mechanical strain.
If you are working out, you need a high-quality sports bra. This is the one instance where the "bras prevent sagging" argument is actually backed by solid biomechanical evidence. Without support during a HIIT workout or a long run, you are actively stretching the internal structures of the breast in a way that the body cannot easily repair.
Smoking and Sun Damage: The Surprising Factors
You might not associate your lungs or the sun with your chest, but they are huge factors in ptosis. Smoking breaks down elastin and collagen in the skin. It literally kills the "springiness" of your body.
Similarly, if you’re a fan of low-cut tops and you don’t wear sunscreen on your chest, the UV rays are destroying the collagen in that thin skin. Sagging is often just as much about the skin's "envelope" as it is about the tissue inside. If the envelope gets thin and papery, it can't hold the weight.
Practical Steps for Breast Health
So, where does this leave you? If you love the freedom of going braless, keep doing it. If you feel more confident and comfortable in an underwire, wear it. Just don't let the fear of gravity dictate your wardrobe.
Check your fit. Most women are wearing the wrong bra size anyway. A band that’s too loose won't provide support, and cups that are too small will just squish tissue in weird directions. Get professionally fitted once a year.
Focus on your "foundation." While you can't exercise breast tissue (since it's not muscle), you can build the pectoral muscles underneath. Exercises like chest presses, push-ups, and flies won't lift the skin, but they can create a fuller appearance by building the "platform" the breasts sit on.
Skincare matters. Treat the skin on your chest like you treat the skin on your face. Moisturize. Use SPF. Keep the skin hydrated so it maintains as much elasticity as possible.
Prioritize movement support. Invest in a real sports bra that limits movement in all directions. If you're a runner, this is the most important piece of gear you own—more important than your shoes.
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Watch your posture. Honestly, half of what people perceive as "sagging" is just a rounded back and slumped shoulders. Standing tall physically shifts the way your chest sits on your ribcage. It’s the easiest "lift" you'll ever get.
At the end of the day, gravity wins. It wins against all of us. Whether you spend $100 on a luxury bra or go through life completely free, your body is going to change. That's not a failure of your wardrobe; it's just the reality of being a human being with skin and bones. Stop worrying about the "shoulds" and focus on what actually feels good on your body right now.