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RED-S – It’s Not Your Favorite Color…

Now that we know what it is not, let’s talk about what it is!

Relative Energy Deficiency in Sport (RED-S).  In simpler terms, it is when the body does not have enough energy needed to perform optimally for health and sports performance.  

When the body does not have enough fuel, it makes adjustments and starts to reduce how energy is used.  This effects hormones, metabolism, and overall function.

And this can lead to a lot of problems now and in the future.

So it’s pretty important to think about, talk about, and be aware of.  Especially when it comes to your young athlete. 

Let’s start with the 3 main presentations of RED-S.  They are low energy level, amenorrhea, and low bone density.  

But it is also important to understand that there are so many more body systems that can be effected by RED-S.

It can lead to problems with metabolism, cardiovascular health, gastrointestinal health, and mental health.  It can impair the immune system’s ability to fight infections and lead to more illnesses.  It can cause high cholesterol.  It can also lead to increased stress and depression.  


This is why RED-S is an important topic to be aware of.

So what can you do about RED-S?  How can you help your athlete to protect their bodies against RED-S?

Fuel is the answer!

Your athlete needs to have enough fuel in order to fully participate in practice.  Without enough fuel, there won’t be enough energy in the tank because the body will try to conserve energy.  And when there is not enough energy, the body starts to redistribute where the fuel goes.  

Organs get energy first.  Then the fight or flight (stress) system.  Then bones and muscles.  Then the immune system.  And the hormones are the last to get fuel.  

So you can see, if the energy source is low there might not be enough fuel for their bones and muscles to work effectively (leading to fatigue and injury).  There might not be enough energy to fight injury or illness (leading to sickness or slower healing times).  And there might not be enough energy for their hormones to function correctly (leading to changes in menstruation, problems with insulin, and issues with growth).

So let’s talk about each of these more specifically.

Bone Health

In females, 50% of their peak bone mass occurs between 11-14 years old.  Peak bone mass doesn’t occur until around 19 years old.  

Estrogen increases the calcium uptake into the blood and deposits it into the bone.  Progesterone helps this activity to occur.  Testosterone helps to stimulate bone growth, formation, and the absorption of calcium.

It has been found that Low Energy Availability (not enough fuel) alone can lead to poor bone health.

Add in the hormones released by stress (which we know is high in teen female athletes) and you have more of a negative effect on bone health.

So, if hormones are not getting the fuel they need, they can not help with bone growth, bone strength, and bone density.  This is what leads to stress fractures and fractures in athletes.

And bone loss in athletes with RED-S may be irreversible!


Primary amenorrhea is when there is no period by 15 years old.  Secondary amenorrhea is the absence of 3 consecutive menstrual cycles. Oligomenorrhea is a cycle that lasts longer than 45 days.

When hormone levels are abnormal, there is low body fat, there is low energy availability, and there is added exercise stress, the result can be changes in menstrual function.

When energy levels are low, the hormones that regulate menstruation are altered which affects the menstrual cycle.

So again, if hormones are not getting the fuel they need, they cannot function properly and the result is a change or dysfunction to the menstrual cycle.

What does RED-S look like?  How do you know if it is occurring?

This looks like anemia, chronic fatigue, increased frequency of illness or infections, and the presence of fractures or stress fractures.

Look for these signs:

  • Your athlete seems more tired than usual during, after, or in between practices
  • Your athlete seems to be getting sick more often
  • Your athlete has recurrent stress fractures
  • Your athlete seems to have slow healing with injuries
  • Your athlete has a change in menstruation (frequency, flow, or delay)

Where does fuel come from?

For athletes, the fuel comes from their food and drink intake.

The important thing is to make sure the athlete is getting enough fuel – are they eating enough of the right things.

A problem with food intake will lead to low fuel, especially for athletes that spend a lot of time at practice.  This can be intentional or unintentional. 

In most cases, it’s likely unintentional.  Things like being a picky eater, having food allergies or sensitivities  or simply not eating the most nutrient dense foods.  

A Registered Dietician Nutritionist is the key here.  These healthcare professionals can help you and your athlete figure out the best foods to eat, when to eat those foods, and how to best fuel your athlete based on their specific practice schedule.

So now what?

Fuel!  Fuel!  Fuel

Just like a car needs fuel in order to operate effectively.  Your very active athlete, needs fuel to operate effectively.

Bottom line: If there is not enough fuel, your athlete can not perform at their optimal level and they can be at risk for significant health problems.

With summer, comes an increase in practice time.  So now is a great time to pay attention to how your athlete is fueling their bodies.  Are they eating enough food and are they drinking enough water?

  • Find a Registered Dietician Nutritionist (RDN)
  • Look for signs of RED-S
  • Allow rest breaks (days or weeks off) if needed
  • Talk to your athlete’s coaches
  • Seek advice from Medical Professionals (primary care doctor, physical therapist, pediatric sports medicine physician)

Early detection is key.  The sooner it is addressed, the better your athlete will be.   

RED-S is best managed by proper fueling, appropriate rest, a reduction in the use of energy, and support from an excellent team.  

Being aware of RED-S can protect your athlete from injury, protect their overall health, and increase their longevity in the sport they love.

If you have any questions, feel free to email me (Jodi@motusvitapt.org).

Click here to join my email list to be the first to get all information related to female athletes, physical therapy, and other health related tips.

For more information about Motus Vita Physical Therapy, head over to my website (www.motusvitapt.org

I’m here to help!  I want the best for your athletes!


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