The Dangers of Very Low Body Fat Levels in Women

by | Jun 11, 2020

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Last updated on January 11th, 2024

We live in a world where the weight management market was worth a staggering US$ 189.8 Billion in 2018. The pursuit of thinness is a global preoccupation. It certainly consumes the thoughts of many athletes. 

In a recent New York Times video, pro runner Mary Cain described how Nike coaches pushed her to lose weight. This led to her developing symptoms of the Female Athlete Triad, which is often ironically shortened to F.A.T. 

The Triad refers to having one or more of the following symptoms:

  • Low energy availability with or without disordered eating
  • Amenorrhea or menstrual dysfunction
  • Low bone mineral density

The female athlete triad concept was expanded to include men in 2014 and the new model is called Relative Energy Deficiency in Sport (RED-S). This condition occurs when intense training goes on for long periods and/or there is an insufficient food intake. This could be due to a lack of knowledge or an intentionally restricted diet with skipped meals and fasting. 

In many cases, overtraining and disordered eating are the result of developing a bad relationship with food. Eating becomes tied up with guilt and shame, or a person becomes so obsessed with eating healthy to the point of orthorexia. 

Elite athletes are at a greater risk of developing the Triad than recreational athletes. As many as 60% of elite athletes face pressure to shed pounds, often without support from qualified nutritionists. And sports that prize aesthetics, leanness, speed and dexterity are particularly susceptible to having athletes present with RED-S symptoms.

Let’s take a look at each of these interlinked symptoms.

Low Energy Availability

LEA doesn’t just refer to fatigue. It means that your body is lacking energy so it focuses on survival. This leads to the shutting down of “non-essential” functions such as getting your period. 

LEA can affect metabolic rate, recovery, immunity and mental health. And it makes sense. If you don’t eat adequately, you’re going to have micronutrient deficiencies. One study of elite gymnasts with LEA found low intakes of pantothenic acid, folate, vitamins D, E and K and minerals including calcium, iron and magnesium. 


Active women who have irregular or absent periods for more than three months have what’s called functional hypothalamic amenorrhea (FHA). FHA is not uncommon among athletes. Your body senses that there’s a lack of available nourishment to sustain pregnancy and child-rearing. Cue the hormone disruption to prevent ovulation.

Not getting a period or being able to get pregnant may seem convenient but FHA comes with many drawbacks. We’re talking issues with protein synthesis, cardiovascular problems, higher total cholesterol and even sexual dysfunction. So you may come across as vitality personified, but if you haven’t had your period in months, it’s literally a red flag.

Hormone disruption can also cause fainting, poor sleep, learning problems, hair loss or facial hair growth, skin issues, inflammation, pain and gastrointestinal distress. That’s a lot to risk for convenience.

In addition, high-achieving people like to push themselves and this type of psychological and physiological stress can cause FHA.

Low Bone Density

FHA impacts hormones such as estrogen. Estrogen, in turn, contributes to bone strength. In fact, many female athletes are diagnosed with the Triad because of injuries including stress fractures. 

It doesn’t matter if you do weight-bearing exercises and take your calcium supplements. If your hormones are disrupted and your period stops, your bones are going to become weaker than an octogenarian’s. I think we can all agree that early-onset osteoporosis should be avoided at all costs. 

Young women are still building up bone density so it’s particularly important not to interrupt this process.

What are the Norms for Body Fat Percentage?

It’s not hard to see why RED-S results in compromised health and subpar performances. As an OCR athlete, you want your body to thrive, not merely survive. The very nature of the sport suggests that striking a balance is best.  

You can move faster with less mass. But you also want to have enough body fat to, for example, buoy you through water during a Spartan race. OCR athletes have to be energetic and strong enough to lift heavy things and get over obstacles. 

Rapid short-term weight reduction is a total no-no. If you want to lose weight to optimize your performance for a particular race, you should aim for slow and steady weight loss in the off-season.

It’s also a good idea to know what body fat percentage to aim for. The American Council on Exercise lists a body fat percent between 14% and 20% as the norm for adult female athletes. Women have higher body fat percentages than men so these figures don’t apply to male athletes and they do go up with age

If your body fat percent is below the 10% to 13% essential fat threshold, you’re asking for trouble. This is territory that only competitive athletes operating in high-stakes environments can enter, and only with extreme caution and backing from a team of health professionals.

The Good News

You can prevent the Triad or get your period back by:

  • Replacing some cardio sessions with weight training to gain muscle and lean mass
  • Creating conditions where you can rest and feel less stressed
  • Seeing a sports psychologist
  • Cutting down on vigorous exercise 
  • Visiting a doctor to rule out issues like thyroid problems and PCOS 
  • Eating more frequently and increasing your intake of protein and nutrient-dense foods
  • Not being afraid of carbs
  • Supplementing with a multivitamin and multimineral as well as amino acids such as L-Glutamine
  • Confirming your BMR and keeping an eye on your caloric balance – as a female OCR athlete, you should likely aim for more than 2,000 calories 

Let’s Keep The Conversation Going

Do you have any questions or comments? I would love to hear them. My favourite place to connect is on Instagram. 

You can also join my free community on Facebook: Sports Nutrition for Teen Athletes, to ask questions and get support from my team and me! I hope to see you there. 

Written by Melissa Boufounos

I’m a certified holistic nutritionist in the Ottawa area. As a longtime athlete, my focus is in performance-based nutrition coaching for young athletes and obstacle course race athletes. My mission is to help the next generation of athletes optimize their nutrition so they can optimize their performance.

Hi, I’m Melissa Boufounos!

I’m a certified holistic nutritionist in the Ottawa area. My mission is to help the next generation of athletes optimize their nutrition so they can optimize their performance.

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