Why Do Female Swimmers Have No Breasts ?! Facts, Myths, and Treatments!

Swimming is a sport/activity that is well-loved and enjoyed by both participants and spectators alike. It is a full-body workout that builds muscular strength and endurance while also challenging the cardiovascular system. Typically, whether done for sport, leisure, and/or from a general passion, swimming is started at a young age. 

Since it is such a common occurrence within the sport of swimming, one may be wondering why female swimmers typically have smaller breasts. Is this normal?  What causes it? 

The sport/activity requires one to use, predominantly, their chest and arm muscles. This results in the upper torso becoming rather muscular. And, this, in turn, causes a natural reduction of breast tissue and fat, and, ultimately, smaller breasts.

So, Yes!, it is completely normal for a female swimmer to have small breasts. (We will be diving deeper into the “What causes it?” part of the equation  throughout this article; so, keep on reading!) 

Post puberty females have pretty much the same amount of glandular tissue in their breasts. Differences in breast size are largely due to fatty tissue and the response of glandular tissue to hormones. Because exercise and diet affect hormones and hormones affect breast size, exercise and diet are factors of breast size as well. (Source A) (Source B) (Source C

Typically, lean athletes will have smaller breasts due to a low [overall] body fat percentage.

Does Swimming Affect Breast Size?

Playing sports and/or being athletic will have an impact on one’s breast size (and swimming is no exception to the list of sports). Therefore, swimming most certainly changes one’s body shape and thereby, the breast size. It generally creates a “V-Shape” build – a long, lean, athletically toned physique with narrow hips & waist, smaller chest, and broad shoulders. 

Breast size has a direct correlation to the amount of glandular tissue which is determined largely by genetics. The more glandular tissue there is, the larger the breasts are. Similarly, the less glandular tissue there is, the smaller the breasts are.  In addition to glandular tissue, breasts are also partially comprised of fatty tissue which is how and why sports and/or cardio exercise can affect their size as well as one’s body size. 

Swimming burns an abundance of calories. How many exactly will depend on your specific body composition, the intensity of your swim, and the duration of your swim. On average one will burn 220-250  calories per 30 minutes of moderate-intensity swimming. Playing sports and/or taking part in cardio/aerobic exercises that burn a significant amount of calories, such as swimming, decreases one’s body fat including in the chest area. The decrease in body fat and glandular tissue within the breasts that results from increased muscle in that area will ultimately yield smaller breasts.  

Though swimming, as well as other aerobic and anaerobic activities, can affect one’s breast size, ultimately, genetics will determine exact breast size – just how large or small they are as well as how much fat they are comprised of

(Source A) (Source B)

Why Do Female Gymnasts Have Small Chests?

There is selective bias in gymnastics as a smaller height and overall frame give one a competitive advantage in the sport. The maneuvers executed in gymnastics are just not suited for those that are tall and/or large. 

As compared to other sports, gymnasts begin rigorous training at a very early age. Often, this rigorous training is commenced before they reach puberty. As a by-product of the rigorous training, gymnasts often under-eat and overtrain which can further delay puberty. This delay in puberty stunts their natural growth and development, and, ultimately, leads to their small size- including their breasts. 

Let’s take a more in-depth look at this matter. Any sport in and of itself- whether gymnastics, swimming, or whichever sport- does not stunt one’s growth and development. Nutrition and hormones on the other hand can stunt one’s growth and development. 

Let’s look at the two main factors for a small chest as well as a small size overall in regards to gymnasts, particularly female gymnasts: 

1- Age and Length of Training 

The rigorous training for gymnastics often starts before puberty which is generally between the age of 10 and 14. Whereas other sports will have their athletes start rigorous training after puberty.  In the world of gymnastics, girls will generally start training around the age of 10.5 and boys will start at roughly 11.5.

This clearly shows that an athlete’s training for gymnastics encompasses part, if not all, of puberty which is an important part of one’s growth and development period. Thus a rigorous diet and training regimen can leave them nutritionally deficient, thereby stunting their growth and development and leading to their smaller size both overall and concerning female breast size. 

2- Fat 

Most gymnasts have low levels of body fat. This in conjunction with the young age of training can also affect one’s growth and development.  The decrease in body fat percentage that comes as a byproduct of rigorous training can lead to a decreased release rate of gonadotropin (GnRH) which ultimately reduces the production of normal sex steroids. This decrease in normal sex steroids causes a decrease in their effects (i.e. it causes a delay in puberty/prevents puberty from occurring as it naturally would).

Lower body fat percentage also leads to lower levels of insulin-like growth factor (IGF-1) which results in reduced growth of the long bones and soft tissue (though more so in the long bones as muscle/soft tissue will hypertrophy with proper exercise and nutrition). Thus those with a lower body fat percentage tend to have not only a smaller frame/overall size but smaller breasts as well. 

The sport itself, as a whole, tends to push its young female athletes to strive for being breastless. Gymnasts do need to be small and agile as well as strong and athletic; starving themselves, however, to decrease their breast size or prevent their development in the first place will only, ultimately, hinder their performance/career and potentially their overall health in the long run. 

(Source A) (Source B

At What Age Do Breasts Stop Growing?

Girls will have their final growth spurt between the ages of 10 and 14, which is also the age range representative of puberty. When exactly one hits puberty within this range varies as growth patterns are largely determined by genetics. Therefore, everyone will grow and develop at a different rate. 

Typically, girls will start to develop breasts around 9-11 years old, give or take. The rate at which breasts will grow/develop is different for everyone. As fatty and glandular tissues grow, breasts grow too-thereby becoming larger. By age of 17 or 18 breasts are fully developed (i.e. they stop growing), though some may take a little longer. 

(Source A) (Source B)

What Foods Give You Bigger Breasts?

Breasts are comprised of glandular tissue as well as fatty and supportive tissue- approximately 80% is glandular tissue and the other 20% is fatty/supportive tissue. Fatty and glandular tissue are what largely determine breast size. Greater fatty and glandular tissue amounts result in larger breasts; however, what you eat has no permanent effect on breast size. 

There is not sufficient evidence showing that specific foods will increase breasts size. Gaining weight can increase breast size, but gaining weight via food can lead to increase weight gain in general which can cause a myriad of other health/wellness issues. 

Natural ways to increase breast size include: 

1- Chest development exercises

 Such exercises include wall press, push-ups, chest press, cobra pose, dumbbell pull-overs, and up-down planks- just to list a few. 

2- Posture 

Good posture won’t physically enlarge one’s breasts, but it can make them look perkier and thereby larger. Exercises to help one with their posture include a child’s pose, plank exercise(s), and cat-cow. Again, just to name a few. 

3- New bra 

Whether your bra is old and no longer supportive, the wrong size, or a combination thereof, it may be time for a new one. A bra that is too tight can make those ta-tas look small and cause less than flattering “spillage” over the sides and back of the bra. On the flip side of the coin, a bra that is too large and provides no support can make breasts look saggier than they really are.

Also, a poorly fitted bra can contribute to back, shoulder, and neck pain. Between wearing and washing, bras will lose their original size and shape over time. 

Strategies that will not work to increase breast size: 

  1. Eating certain foods 
    1. There is no clinical or scientific evidence that any specific food will enhance breast size. Therefore, such claims are false. 
    2. Dairy and Soy-based products are no exception to these claims 
  2. Breast enlargement supplements or creams 
  3. Massages or pumps 

Breast size is largely determined based on glandular & fatty tissue and genetics; however, lifestyle, hormones, body weight (specifically gaining weight), age, and life stages such as menstruation and pregnancy (which affect hormones)  will also affect one’s breast size. While one can’t change the size of breasts themself, one can improve the size, strength, tone, and overall appearance of those pectoral muscles (chest muscles behind breasts) which can give the appearance of perkier and/or larger breasts. 

 (Source A) (Source B

Do Sports Bras Stunt Breast Growth?

Over the years there has been much debate over whether wearing a sports bra stunts breast growth. However, the claim that wearing a sports bra will stunt breast growth and development is, in fact, a myth and therefore, not true. So, we can just go ahead and throw that claim into the deep end.  

Sports bras typically come in low, medium, and high impact variations; so, there is a fit/style for virtually any and everyone. They’re designed to prevent bouncing around. Some research shows that bouncing around can slowly diminish connective tissue which ultimately makes up the shape of your breasts; so, indirectly, a sports bra can help preserve the shape of one’s breasts (at least during physical activity). 

While this compression is ultimately a good thing, particularly during physical activity,  it is very well possible to have too much of this good thing. Sports bras are often too tight which can weaken back muscles, cause shoulder pain, and have adverse effects on your posture. So, while they won’t stunt the growth of breasts,  it’s not good to wear them (or any tight/constricting clothing for that matter) all day.

Furthermore,  this excessive constriction can press on the lymph system which can lead to tenderness and/or discomfort after a while. Also, skin issues such as a rash or fungal infection can stem from irritation due to the constriction from/tightness of the material against the skin and chafing. 

So, if a sports bra is more comfortable for you, go ahead and rock one over a “regular” bra.

Just be sure it is properly fitted- not too tight or too loose- and don’t wear it all day. Perhaps, keep the sports bra for working out/physical activity and opt for a soft wireless bra, bralette, or “lounge bra” (a whole new category of bras) for your Work From Home 9-5 and/or lounging. 

(Source A) (Source B

If you are looking to find a decent affordable trusty bra for your next sports adventure, then we recommend that you check out the Reebok Women’s Tri-Back Sports Bra, Light Support (Amazon Link) Designed specifically for sports and Training with a Speedwick fabric wicks sweat to allow you to stay cool and dry

Does Sleeping without A Bra Increase Breast Size?

It is neither good nor bad to sleep with a bra on. It is a matter of preference and 100% up to the individual as there is no research or evidence to suggest that it is either harmful or significantly beneficial.

If one finds it comfortable to sleep with a bra on, then, it can be beneficial. Though some women find it more comfortable to sleep in a bra, for various reasons, no proof wearing one through the night has any significant effect on breast tissue. Just as there are no major benefits to sleeping without a bra there are no major drawbacks or harmful effects of sleeping in one.  So, it’s all a matter of personal comfort- regardless of one’s decision, it will not affect their breast size. 

Furthermore, a  bra does not prevent sagging- sagging is a by-product of gravity and mother nature. Wearing a bra to sleep will not cause or prevent sagging, preserve breasts, or stunt breast growth/development. Also, wearing a bra of any kind, night or day, does not cause cancer. 

Though it is a personal preference whether or not to sleep with a bra on as there is no direct correlation between sleeping with a bra on and increased breast size, it is still important to assure that your bra is properly fitted- not too loose or too tight- if you are choosing to sleep with one on. A sports bra can be a good choice- just go with one of the low-impact styles. Or, perhaps, opt for a style from the new “lounge bra” category of bras. Ultimately, one wants to avoid underwire as it can cause discomfort and the wire is often made of highly allergenic nickel. 

(Source A) (Source B)

What Are the Disadvantages of Not Wearing a Bra?

Studies show that more than 80% of women are wearing the wrong size bra – approximately 70% of women are wearing bras that are too small, while 10% are wearing bras that are too big. So then, why not go braless and eliminate the sizing issue? Are there any disadvantages to not wearing a bra? 

There’s no evidence that not wearing a bra will have any significantly harmful or beneficial effect on one’s breast health or permanent appearance. Rather, many biological and genetic factors affect breast health and [permanent] appearance. These factors include weight, genetics, and life stages such as pregnancy & breastfeeding, and menstruation. 

While wearing a bra or not will not impact the size or shape of one’s breasts or increase one’s risk of cancer, there is evidence that those with a larger cup size may find it more comfortable to wear a bra because it can provide the support that helps alleviate musculoskeletal- particularly back- pain that often results from the weight of breasts. Also, it is recommended that one wear a sports bra during sports/physical activity as not doing so can increase the risk of damage to the connective tissue (Cooper’s Ligaments)  in breasts. 

So, the only real disadvantages to not wearing a bra are aesthetics (or lack thereof) and a lack of proper support which can potentially lead to pain/discomfort. Ultimately, whether or not one wants to wear a bra is a matter of personal preference and comfort. 

If you feel comfortable without a bra, go au natural/braless.

However, if you prefer to have some support for those ta-tas and/or just enjoy wearing a bra for every occasion, that’s absolutely ok too- just assure your bras fit properly. 

(Source A) (Source B) (Source C)

Melissa Frank

My passion, outside of animals, is helping people and adding value to their lives…I strive to leave the world a little better than I woke to it each day. The first part of my career, for a total of about 15 years, was spent in the public safety field as a Volunteer Firefighter/EMT-B and 9-1-1 Operator. In 2019 I obtained my personal trainer certification (ACE certified) as well as many group fitness certifications and certification as a Corrective Exercise Specialist.

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