red-s & the female athlete triad

Start Here: The Language Has Changed

For years, the conversation around under-fueling in female athletes centered on something called the Female Athlete Triad — a syndrome defined by three interconnected components: low energy availability, menstrual dysfunction, and low bone mineral density.

About 20 years after Title IX, physicians identified this set of three symptoms commonly seen in women athletes. Malnutrition led to abnormalities in the menstrual cycle, which in turn affected bone density.

But the clinical community has since recognized that this framework was too narrow. In 2014 the International Olympic Committee introduced RED-S — Relative Energy Deficiency in Sport — to expand the diagnosis beyond the Triad and capture the full range of consequences that low energy availability can produce across multiple organ systems.

Understanding both terms matters — because you'll hear them used interchangeably, and they're not quite the same thing.

The Female Athlete Triad — What It Is

The female athlete triad is a condition seen in physically active female athletes consisting of low energy availability, menstrual dysfunction, and low bone mineral density. It should be viewed as a metabolic injury — one that can impact female athletes at any age or level, with activities emphasizing leanness, aesthetics, and endurance carrying the highest risk.

The three components are deeply connected — and they feed into each other:

1. Low Energy Availability — This is the root of everything. Low energy availability doesn't just mean eating too little, it means not consuming enough to cover both your exercise demands and your body's basic physiological needs. Many athletes don't have eating disorders — they simply don't understand how many calories they need to compensate for their level of training. The result is a chronic energy deficit that the body responds to by shutting down non-essential systems — starting with reproduction.

2. Menstrual Dysfunction — When energy availability drops too low, the body suppresses reproductive hormones to conserve resources. The result is irregular or absent periods — known as oligomenorrhea or amenorrhea. This is not a sign of fitness. It's a warning signal. Bone density has been shown to negatively correlate with the number of missed menstrual cycles since menarche — meaning the longer menstrual dysfunction goes unaddressed, the greater the long-term consequences for bone health.

3. Low Bone Mineral Density — Athletes affected by the triad may have bone density lower than expected for their age — in some cases low enough to be considered osteoporotic or in early stages of bone loss. In adolescent athletes who are still building bones, the consequences are particularly serious — they may not build enough bone, increasing fracture risk for the rest of their lives.

Bone Health & Stress Fractures

This is where under-fueling becomes a structural injury risk — not just a performance issue.

Stress fractures account for up to 20% of all injuries treated in sports medicine clinics. Prolonged low energy availability leads to an amenorrheic state, estrogen deficiency, and dysfunction of other hormones required for bone health — resulting in impaired bone health and significantly increased stress fracture risk. Read More →

The combination of amenorrhea and demanding training dramatically increases stress fracture likelihood — with one study reporting that amenorrheic ballet dancers who practiced more than 5 hours a day were more likely to sustain a stress fracture.

For student athletes who are already managing high training loads and academic stress, this isn't a distant concern. It's a real and present risk.

Why This Affects Female Athletes More

While RED-S can affect athletes of any gender, female athletes face a specific convergence of risk factors that makes them disproportionately vulnerable:

• Hormonal cycles that already affect energy availability and bone metabolism.

• Sports culture that often equates leanness with performance.

• Weight-class sports that incentivize restriction.

• Aesthetic pressure that exists in women's athletics in ways it doesn't in men's.

For some competitive female athletes, low self-esteem, perfectionism, and family stress place them at additional risk for disordered eating — which can accelerate the development of the triad or RED-S.

And critically — it is important to emphasize that low energy availability does not always have to be accompanied by an eating disorder. The symptoms can be manifold and vary considerably between individuals, complicating diagnosis and treatment. Many athletes develop RED-S without ever meeting the clinical criteria for an eating disorder. They're just not eating enough — and they don't know it.

If anything on this page resonates with your experience, speaking with a registered sports dietitian is one of the most important steps you can take. A sports dietitian — particularly one who works with athletes — can help you assess your energy availability, understand your relationship with food and fueling, and build a plan that supports both your performance and your long-term health. You don't have to be in crisis to benefit from that conversation.

For a broader overview of RED-S in female athletes: Read More →