The Cost of Under-Fuelling for Female Athletes

Key Takeaways

• Under-fuelling impacts female athletes earlier and more severely, especially in bone and reproductive health.

• Proper nutrition is vital to protect bone health, which is at greater risk in women.

• The menstrual cycle is a powerful tool for monitoring energy availability and overall well-being.

• Coaches play a crucial role in supporting athletes with open communication and tailored fuelling strategies.

Introduction: What is Under-Fuelling?

Under-fuelling happens when there is a mismatch between the energy taken in (through food) and the energy expended (through training, daily activities, and essential bodily functions). Simply put, the body does not get enough fuel to meet its demands.

While under-fuelling negatively impacts all athletes, female athletes often experience its consequences sooner and at milder levels of energy deficit compared to males. This creates an added responsibility for women to be proactive in ensuring adequate fuelling.

Bone Health: A Non-Negotiable Priority

Both men and women are at risk of impaired bone health from under-fuelling. However, women generally have a lower peak bone mass and lose bone density earlier and faster than men.

As a result, under-fuelling poses a greater risk for adverse bone health in female athletes. Protecting bone health through proper nutrition is non-negotiable for a sustainable athletic career (Tenforde et al., 2016).

Menstrual Health: A Built-In Energy Gauge

Under-fuelling disrupts reproductive function in both sexes, but in women the effects are more visible and immediate. Energy deficiency can blunt the hormonal fluctuations of oestrogen and progesterone, effectively “switching off” the menstrual cycle.

This condition, known as functional hypothalamic amenorrhea, leads to missed periods, absence of ovulation, and temporary infertility. Beyond fertility concerns, menstrual dysfunction is a clear sign that the body is under-fuelled and not functioning optimally.

Monitoring Menstrual Health

Unlike men, women have a built-in system to partially monitor their energy availability — their menstrual cycle. This gives female athletes a powerful and personal tool for insights into how well they are fuelling.

Ways to monitor menstrual health include:

• Progesterone testing: A time-specific blood test can measure progesterone levels.

• Ovulation kits: Over-the-counter urine tests can help assess ovulation patterns.

• Period tracking: Regular periods every 21–35 days are considered normal. Periods that become infrequent (longer than 35 days apart) or stop altogether are red flags.

• Developing strong body literacy — knowing cycle patterns and what is normal — is essential. Early identification of menstrual irregularities can prompt timely interventions, preventing long-term adverse health consequences and optimising training and performance.

Guidance for Coaches

• Encourage open, stigma-free conversations about fuelling and menstrual health.

• Recognise missed or irregular periods as potential signs of under-fuelling, not “normal” side effects of hard training.

• Support athletes in maintaining adequate energy availability through personalised and fit-for-purpose nutrition strategies.

• Advocate for regular health check-ups, with particular focus on bone and menstrual health.

References

• De Souza, M. J., et al. (2014). Female Athlete Triad Coalition Consensus Statement on treatment and return to play of the female athlete triad. British Journal of Sports Medicine.

• Elliott-Sale, K. J., et al. (2021). Methodological considerations for studies in sport and exercise science with women as participants: a working guide for standards of practice for research on women. Sports Medicine.

• Mountjoy, M., et al. (2018). International Olympic Committee (IOC) consensus statement on Relative Energy Deficiency in Sport (RED-S): 2018 update. British Journal of Sports Medicine.

• Tenforde, A. S., et al. (2016). Association of the female athlete triad risk assessment stratification to the development of bone stress injuries in collegiate athletes. The American Journal of Sports Medicine.

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