The Real Dangers of Energy Deficiency in Female Athletes

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In 1972, a short but powerful federal law was passed:

"No person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any educational program or activity receiving Federal financial assistance."

Title IX was an awesome win for women in sports. As a result, over the last few decades, girls' interest and participation in sports has exploded. As interest has grown, so has competitiveness.


In 1972, a short but powerful federal law was passed:

"No person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any educational program or activity receiving Federal financial assistance."

Title IX was an awesome win for women in sports. As a result, over the last few decades, girls' interest and participation in sports has exploded. As interest has grown, so has competitiveness.

With scholarships to earn, championships to win and records to break, things like irregular cycles and missing periods get pushed to the back burner.

After all, getting pregnant is the last thing on the minds of most high school and collegiate athletes. So why does menstrual health matter for them now? The reality is hormonal health plays a huge role in the overall health and performance of women in sports. It can affect both performance today and for the rest of their lives.

Studies show up to 60% of female athletes experience menstrual irregularities while 30% are amenorrhoeic or missing their periods altogether.

Missing periods are a big warning sign for a deep, underlying issue that, if left unaddressed, could have disastrous long-term consequences.

We're talking about Relative Energy Deficiency in Sport (RED-s) and how hormonal health affects not just today's performance, but long-term success.

The Incredible Body of the Female Athlete

Skipping a period doesn't seem like a big deal in light of the hectic day-in,-day-out grind of training and tournaments. In fact, in some social circles, it's even a source of pride to say that you've "trained hard enough" to get to this point. But that's a dangerous myth.

In our article about female athletes and menstruation, we covered how important menstruation is as a sign of hormonal and nutritional health.

The body of a female athlete is an incredible machine.

Take for instance the long-distance runner Jasmin Paris, who recently destroyed the course record for the 268-mile UK "Spine Race" Ultramarathon.

What made her performance all the more inspiring was that she showed having healthy hormonal production is not just possible for an elite athlete, but essential to their performance.


She beat the previously held record by 12 hours while expelling breast milk for her toddler at aid stations throughout the race.

The truth is, hormonal health is a signal of overall health. Your body should be able to perform at peak while maintaining a healthy level of activity in its other systems.

Female athletes, especially at the high school and collegiate level, risk short-term performance consequences of the Female Athlete Triad (decreased energy availability, menstrual dysfunction and increased risk of bone injury) when they don't fuel their bodies for recovery.

But let's face it: We aren't just creating athletes for the college scholarships.

Girls are athletes because they love the sport.

Because they love the challenge.

Because it's part of who they are.

If you're high performance, being an athlete is part of your identity. But being an athlete for life means not just performing your best now, but building a body for the future.

It's critical that athletes, coaches and parents understand the way a female athlete's body recovers and builds; paying attention to the warning signs it throws our way.

Studies into the Female Athlete Triad have led us to a broader understanding of the unique risks female athletes face. In this article, we go beyond the warning signs of hormonal imbalance and talk about the elephant in the room: RED-s.

Female Athlete Triad And RED-s

In the early 1990s, sports science research identified the Female Athlete Triad as a syndrome occurring in female athletes involving the interplay of these three things:

  1. Decreased energy availability (i.e., low intake and body fat)
  2. Menstrual dysfunction
  3. Poor bone health

Identifying the problem was the first big step in helping girls become healthy and successful lifelong athletes. Studies showed that if problems were identified and addressed early, most damage was reversible.

But identifying the Female Athlete Triad wasn't a fix-all.

With this definition, scientists were limited in their understanding of how this syndrome was caused and its effects. As participation in athletics boomed, more studies began to indicate that female athletes weren't required to have severely low body fat to suffer from symptoms of the Female Athlete Triad.

Something was happening, and not just to girls. Male athletes were also showing an increased risk of fractures, hormonal disruptions, decreases in performance and higher long-term risk of poor skeletal health.

So, in 2014, the IOC broadened its statement to address the gaps of previous research, introducing us to an overarching issue called RED-s.

In the most updated statement (2018), the IOC produced a consensus statement on RED-s relative energy deficiency.

They defined Relative Energy Deficiency in Sports as: "The impaired physiological functioning caused by relative energy deficiency and includes, but is not limited to, impairments of:

  • Metabolic rate
  • Menstrual function
  • Bone health
  • Immunity
  • Protein synthesis
  • Cardiovascular health" [2]

The cause? Low energy availability.

What Is Low Energy Availability?

Low energy availability (LEA) is the driving force behind RED-s. It happens when a mismatch exists between an athlete's energy intake (her diet) and the energy expended in exercise.

When a female athlete isn't consuming enough energy to match exertion, the body has trouble finding the energy it needs to support itself as a whole. This causes an athlete to suffer both in short-term performance and long-term health.

In the lab, we can calculate the LEA by:

[Energy Intake (kcal) – Exercise energy expenditure (kcal)]/ Fat-Free Mass (kg)

The optimal energy availability is about 45kcal/kg of fat-free mass.

When the number nears 30kcal/kg of FFM/day, the athlete runs at a much higher risk of experiencing ailments like:

  • metabolic rate disruption
  • menstrual disruption
  • loss of bone mass
  • Cardiovascular issues

Although research shows LEA is the underlying cause of RED-s, the methodology of recording intake by self-reports is flawed.

This human error makes it difficult to determine exactly when an athlete is in danger and how much more they need to consume to make up for energy loss.

The Unreliable Food Log

Human error makes LEA, and its connection to RED-s, very difficult to accurately study. Most studies on the topic have revolved around self-recorded food diaries. These diaries often rely on memory and relative measurements. With all of the other immediate concerns our athletes face, it's no wonder that research indicates most food intake records severely underreport what is actually being consumed.

Even more, the LEA calculations above are an approximate for the "normal" female athlete. But what does "normal" mean?

Since opening Relentless Athletics in 2014, I've trained hundreds of female athletes. "Normal" is a bell curve, and no two athletes are the same.

Food intake logs are just one diagnostic tool that can help us determine if energy availability is low relative to an athlete's level of energy needs.

More so, food logs can't always tell us "why" there's a deficit. Is low food intake an accident, perhaps the result of a particularly busy schedule and skipped meals? Or does it represent a larger issue, like a clinical eating disorder?

A Quick Word on Eating Disorders

LEA stemming from true eating disorders is a whole different game.

But how can you tell if an eating disorder is the root cause of under-fueling?

When working with coaches and parents on nutrition, here are some red flags I ask they watch for:

  • Unusually high intake of fiber
  • Use of Stimulants
  • Artificial sweeteners
  • Purposely high intake of low-energy density foods
  • High dietary restraint (rules, habits, anxiety surrounding food)
  • Poor energy levels throughout the day

These habits may be signs of a more serious problem than just not eating enough food on game day.

You may have read this article on how Instagram model Ruby Matthews recently admitted her diet was "a life of tapas and cocaine." Obviously, it seems absurd to think the athlete you're coaching would ever go to such an extreme. However crazy it seems, you have to be aware that these are the social models all women are exposed to every day.

The girls we parent and coach are constantly bombarded by images defining what is "attractive" and "accepted." It's not hard to imagine an athlete, trying to compete with social media models, developing a poor relationship with food.

In a 2012 study performed on Division-I female soccer players, researchers at Penn State noted that 29% of the athletes experienced LEA (< 30kcal/ kg FFM) during the pre- and mid-season. Additionally, these researchers found a strong relationship between those athletes experiencing LEA and those athletes who demonstrated high body dissatisfaction and a high drive for thinness.

When LEA stems from disordered thinking (which often stems from misinformation and unrealistic body types in the media and gurus pushing detox diets and quick fixes), proper nutrition education is key (more on this in a bit).

However, LEA stemming from true eating disorders requires clinical help.

You, as a parent or coach, cannot and should not address larger psychological concerns such as obsessive-compulsive, anxiety, and controlling behaviors on your own.

Unintentional Under-Fueling

Many female athletes suffer from LEA stemming from inadvertent underconsumption or resulting from disordered eating patterns (not true disorders, but issues generally based on misguided information based on individual experience and not research-based repeatable studies ).

What's the solution?


Solving this issue requires education in basic scientific principles of metabolism and sports nutrition. I'm not saying go get a PhD, but I'm saying that knowledge is power in helping athletes.

Female athletes need to understand the energy demands their sport has on their body, they need to wrap their heads around the science of how food fuels their body and helps meet those demands, and they need to learn about the misinformation and social pressures that exist around them.

Instagram "gurus" and models can wreak havoc on real nutritional science.

With nutrition being just as important (if not more) as training for an athlete, it's no wonder female athletes struggle more with LEA under the pressures and misinformation of the social media age.

Raising Lifelong Athletes

RED-s and LEA have real, lifelong consequences to our girls.

When your body is severely undernourished, it takes certain steps to CONSERVE energy for more important bodily processes (such as your brain's ability to function!). When this happens, RED-s becomes a serious syndrome with dangerous long term risks. The body is a system, and when one area is affected by low energy availability, other areas feel it.

These long term effects include:

  • alterations to the endocrine system
  • poor metabolic function
  • disruption of menstrual function
  • weakened bone health
  • And damage to both cardiovascular and gastrointestinal functions

Here's what happens to a female athlete suffering from REDs.

With low LEA, your body enters conservation mode.

This mode flips on thanks to some endocrine changes that influence your hormonal production and circulation.

The main disruption is seen along the hypothalamic-pituitary-gonadal axis. In this axis, your hypothalamus, pituitary and gonadal (ovaries & uterus) glands communicate to each other through hormone release.

In the LEA state, females demonstrate a decrease in Luteinizing Hormone (LH) release from the hypothalamic-pituitary axis, resulting in a decrease in estrogen release in the gonads.

In a healthy female athlete, LH spikes prior to ovulation. With a decrease in LH release and associated hormones that are affected by LH concentration (like estrogen and progesterone) ovulation can become disrupted and even come to a complete halt.

Additionally, a decrease in food availability affects other hormones in the body.

Energy conservation affects thyroid function and changes appetite, affecting the athlete's regulating hormones (decreased leptin, oxytocin, increased ghrelin, peptide YY and adiponectin, decreases in insulin and insulin like growth factor, increased growth hormone resistance, and elevations in cortisol levels).

It makes sense.

If the body isn't getting enough energy, it's going to conserve what it can for its most vital processes. Unfortunately, this means the production of important hormones is pushed to the side in favor of brain and organ function.

LEA also plays a role in influencing the hormones that take part in follicular ovulation.

In functional hypothalamic amenorrhea (FHA), a disruption of the gonadotropin-releasing hormone at the hypothalamus causes alterations in LH and FSH release. This, in turn, causes a decreased estrogen and progesterone levels.

Multiple studies show a direct relationship between the magnitude of the energy deficit and this decrease.

Why is missing or irregular ovulation a problem? Because during these fluctuations in your hormones, your bone health gets hit hard.

Most medical practitioners prescribe oral contraceptives to help reduce irregularity. But here's the problem: Oral contraceptives introduce a synthetic version of estrogen and/or progesterone to create the hormonal environment that occurs with fertilized egg implantation. The idea is, if your body thinks it is pregnant, it cannot become pregnant.

On the last week of the pill (or the placebo pills), the hormones are removed, telling the body no egg was implanted and it's time to shed the uterus lining.

Here's the issue:

  • Introducing a synthetic hormone decreases your body's own production of that hormone, and those hormones play a part in more than just our sex hormone. Men have estrogen, too, and it's not because they have ovaries!
  • The data regarding the positive effects of combined oral contraceptives on bone mineral density and fracture risk are inconsistent with the most recent studies which have found no increase or even a decrease in bone mineral density with oral contraceptive use.

Basically, prescribing oral contraceptives treats a symptom, not the root cause.

If a medical practitioner does prescribe oral contraceptives, you must be aware that they might mask spontaneous menses, and bone loss may continue if the energy deficit is not also corrected.

For this reason, the IOC does not recommend the use of oral contraceptives for the sole purpose of regulating menses in athletes suffering from RED-s.

Bone health is directly tied to a female athlete's menstrual health.

When an athlete's cycle is interrupted (known in the medical community as oligomenorrhea) or completely disappears (amenorrhea), her bone health is at serious risk. These hormonal disruptions cause

  • Decreases in bone mineral density
  • Altered bone microarchitecture
  • Alterations in bone repair
  • Decreases in bone strength

Why does this matter?

All of this puts our girls at an INCREASED risk for stress fractures and other bone-related injuries.

How? Malnutrition affects more than just energy levels, it also affects micronutrient levels.

For females with RED-s, there is a high chance they are NOT getting enough micronutrients for optimal health. Essentially, they aren't consuming enough to provide for their vitamin D and calcium needs- two micronutrients that are essential to musculoskeletal strength.

A lack of energy, combined with a lack of these essential micronutrients, makes it more difficult for the body to recover from load-bearing activity.

In short: weak bones mean a high risk of injury.

Weak bones in young, developing athletes now can lead to a lifetime of medical issues.

Why? Bone mass for the female athlete peaks in our 20s. At 26, females have typically reached 99% of their bone mineral content. This isn't something that can be easily "fixed" down the road.

Reversing the bone mineral loss process is a priority for adolescent and teen females suffering from RED-s.

The only way to do this is by addressing the low energy availability problem head on through nutritional programs that balance an athlete's unique level of activity.

If hormonal trouble and the risks of lifetime skeletal issues weren't enough to convince you, LEA also causes damage to both the cardiovascular and gastrointestinal system of the female athlete.

Athletes suffering from LEA have a lowered heart rate and systolic blood pressure. These changes in cardiovascular health increase with the deficit between food vs. output, and can cause valve abnormalities, pericardial effusion, severe bradycardia, hypotension and arrhythmias.

Gastrointestinal distress is also a common symptom of LEA. As athletes lack enough intake, they can suffer from issues like:

  • Constipation
  • delayed gastric emptying
  • altered sphincter functions
  • and stool leakage

It all comes down to putting stress on the body.

Lack of energy intake is stress. GI distress is stress. Menstrual disturbances are stress. CV alterations are stress.

All this stress without recovery is detrimental to the athlete. It increases her risk of injury and illness.

Of course, in a high-stress environment, the chances of optimal recovery are slim. This not only causes a performance decrease in today's game, but next season, too.

Under-Fueling Undermines Performance

Lower energy availability.

Hormonal imbalances.

Weakened bone structure.

Compromised cardiovascular and gastrointestinal health.

When an athlete is working with a sub-optimal system, her performance will also suffer.

Food is the fuel that provides the energy you need for high bursts of activity. In the short term, LEA affects the amount of fuel available to muscles to perform at the moments we need them the most.

Over the course of a season, LEA affects an athlete's ability to recover.

Replenishment of glycogen stores and protein synthesis is impeded without proper supply of energy. This has a huge negative impact on an athlete's physical, mental, and psychological capacity to handle the high-intensity challenges of her sport.

Addressing RED-S

Relative Energy Deficiency is a serious problem in female athletics.

In a world guided by social media "realities," there is a high emphasis on appearance and a pressure for "thinness" placed on our athletes.

For adolescents exhibiting LEA, they are at a corresponding higher risk of depression, psychosomatic disorders and have more trouble managing stress.

Our work, as trainers, coaches and parents is to educate our athletes to help proactively address the risks of under-fueling.

For younger female athletes, knowledge is key to helping them perceive food as fuel. We must teach them the NEEDS of their body and how these affect their ability to perform and recover.

Giving young female athletes a foundational understanding of nutrition helps them develop a positive relationship with fueling as their level of performance increases.

If your athlete is already exhibiting symptoms like:

  • loss or disruption of menstruation
  • high rate of soft tissue or bone injuries
  • frequent sickness
  • chronic fatigue

Or showing a disordered relationship with food: (doing "detox" diets and cleanses, purposefully intaking high amounts of fiber, overusing stimulants, or exhibiting high anxiety around food), the time to act is NOW. Parents and coaches, don't be afraid to seek help from a nutrition coach or an expert in the field.

After all, the life of a young athlete is stressful.

You're already helping them develop a love of sports through physical training, teamwork, coaching and mental strength…nutrition education is just another important part of helping them succeed for life.


Photo Credit: iammotos/iStock