Rethinking Menstrual Health Research in Female Athletes: What Dietitians Need to Know

Over the past decade, research into menstrual health and sports performance has grown significantly. As a dietitian working with active women, this is a positive and much-needed shift. However, despite the increase in research, the way many studies are designed may limit how applicable their findings are in real-world settings. Insights from recent expert discussions at the European College of Sport Science conferences in 2024 and 2025 highlight the need to rethink how we approach menstrual cycle research, particularly if we want it to translate meaningfully into practice.

A large proportion of current research focuses on women with so-called “textbook” menstrual cycles, known as eumenorrheic cycles. These are defined using strict criteria, including specific cycle lengths, confirmed ovulation, and precise hormonal profiles. While this improves scientific rigour, it also creates a significant limitation: it excludes a large proportion of real women. In practice, many female athletes experience variations in their cycles. Research suggests that up to 30% of cycles may be anovulatory, even in otherwise healthy women, and when subtle disturbances are included, as many as 50% of exercising women may not meet the criteria for a “normal” cycle. In addition, a substantial proportion of female athletes use hormonal contraception. This means that much of the research may not reflect the populations dietitians are actually working with.

Another important insight emerging from recent studies is that changes in performance, recovery, and training responses appear to be more closely linked to symptoms rather than hormone levels themselves. Symptoms such as fatigue, low mood, poor sleep, and gastrointestinal discomfort often have a more noticeable impact on training than fluctuations in oestrogen or progesterone. Importantly, these symptoms do not always align neatly with defined menstrual cycle phases. This highlights the need to move away from a rigid, phase-based approach and instead focus more on the individual experience of each athlete. Dietitians play an extremely important role here by identifying where diet can support prevention of these symptoms. For example, suboptimal or deficient levels of iron will greatly impact fatigue waves.

By focusing narrowly on “normal” cycles, research may also be overlooking important areas such as subtle menstrual disturbances. These include issues like short luteal phases, inconsistent ovulation, or minor hormonal disruptions that may go unnoticed without detailed monitoring. While more severe conditions are well recognised within frameworks such as Relative Energy Deficiency in Sport, far less is known about the impact of these more subtle variations. In some cases, these disturbances may even be adaptive responses to training or stress, but their implications for performance and long-term health remain unclear.

Hormonal contraception is another area where the research base is still limited. Although its use is widespread among female athletes, most studies have focused on the combined oral contraceptive pill, with far less attention given to progestin-only methods, intrauterine devices, injections, or other delivery systems. Each of these creates a different hormonal environment, which is likely to influence metabolism, recovery, appetite, and overall performance. Expanding research in this area is essential if we are to provide meaningful, evidence-based guidance.

There is also a disconnect between how performance is studied and how it occurs in reality. Much of the existing research assesses athletes in a rested state, yet in practice, athletes often need to perform under fatigue, whether that is during prolonged endurance events or across multiple rounds of competition. Understanding how hormonal fluctuations influence fatigue, resilience, and recovery in these conditions is a key gap that needs to be addressed.

Looking ahead, both research and practice need to adopt a more inclusive and individualised approach. This means including a wider range of hormonal profiles, considering the effects of hormonal contraception, and studying athletes in real-world training and competition environments. It also means recognising that responses vary significantly between individuals. Tracking patterns over time, including symptoms, cycle characteristics, performance, and recovery, can help identify trends that are far more useful than relying on generalised assumptions.

In practice, this has several important implications for dietitians. Rather than relying solely on cycle phase to guide nutrition strategies, it is more effective to focus on how an athlete feels and performs. Monitoring factors such as bleed characteristics, energy levels, mood, training output, and appetite can provide valuable insight. Thinking about what may be nutritionally driving these factors behind the scenes becomes critical. This approach allows for more responsive and personalised nutrition support, rather than applying rigid, phase-based recommendations.

It is also important to be aware of subtle signs that may indicate underlying issues, such as consistently poor recovery, recurring dips in performance, or inadequate energy intake. These may point towards early stages of low energy availability or hormonal disruption, even in the absence of obvious menstrual irregularities. Working collaboratively with coaches, physiologists, and medical professionals is particularly important when these concerns arise.

Ultimately, the field is moving away from a one-size-fits-all model of female physiology. The future lies in individual tracking, symptom-led strategies, and approaches that reflect the realities of training and competition. For dietitians, this presents an opportunity to play a key role in bridging the gap between research and practice, helping female athletes optimise their health and performance across all phases of their cycle. So exciting!