Restoring Cycles: How We Beat Amenorrhea in an Endurance Athlete

A 28-year-old female athlete in Melbourne restored her menstrual cycles from zero to six consecutive cycles within 24 weeks. Most people would have called this burnout. It wasn't: it was plain old underfuelling, exacerbated by a misunderstanding of her body's energy demands.

The presenting state

Most clinicians would have looked at her lack of period and just said, "eat more." Of course, that's part of it, but it glosses over why the body shuts down such a vital system. Her body wasn't just in an energy deficit; it was in a perceived threat state. Chronic low energy availability tells the body, in no uncertain terms, that it's not safe to reproduce, so it quite sensibly turns off non-essential systems like ovulation. This isn't just about weight; it's about perceived resource scarcity, triggering a widespread sympathetic nervous system response where reproduction becomes a luxury the body can ill afford (Chrousos, 2009).

Her interoception — the fancy word for how you feel your internal body cues, or how well you listen to what your gut is telling you — was pretty muddled. She was so disconnected from her hunger signals that she genuinely believed she was eating enough. Her gut-vagal axis, the two-way communication highway between the gut and the brain via the vagus nerve (which influences everything from heart rate to digestion), was consistently registering stress. This wasn't about willpower; it was about a deeply ingrained system telling her she was perpetually running from a saber-toothed tiger.

The protocol

The goal wasn't just to make her eat more; it was to shift her physiology out of perceived threat, restoring trust in her body's signals, and convince her HPO axis (hypothalamic-pituitary-ovarian axis, the control centre for reproduction) that it was safe to come back online. My approach is never about rigid rules; it's about recalibrating the internal compass. We focused on making eating a restorative, safe act, rather than a refuelling task. The mechanism? Downregulating the sympathetic alarm bells by providing abundant, consistent energy, allowing the ventral-vagal state (Porges, 2022) — which promotes rest, digest, and social engagement — to take over.

Fuelling intervention: Gradually increasing caloric intake, focusing on nutrient-dense, whole foods, particularly carbohydrates and healthy fats.
Cycle-aware training: Restructuring training around her natural hormonal fluctuations, reducing intensity during perceived vulnerable phases.
RED-S protocol: Addressing all components of Relative Energy Deficiency in Sport, not just energy intake, but also micronutrient status and gut health.
Interoceptive practice: Gentle exercises to reconnect with hunger and satiety cues, improving gut-brain communication.
Stress reduction: Implementing structured downtime and recovery practices to lower overall allostatic load.
Sleep optimisation: Prioritising consistent, quality sleep to further support hormonal regulation.

What changed

Her primary success metric was straightforward: from zero cycles in 18 months to six consecutive, regular cycles within 24 weeks. This wasn't just an arbitrary count; it represented a fundamental shift in her physiological state. Alongside this, her LH:FSH ratio — a critical marker for ovarian function that was initially out of whack, indicative of hypothalamic suppression — fully normalised to a luteal-phase appropriate ratio. This is a big deal, as it signals that the HPO axis was no longer in lockdown. It was quite satisfying to see that particular marker fall into line.

The nerdy detail I loved: her HRV (Heart Rate Variability) started showing a distinct increase in parasympathetic activity, particularly overnight. Initially, it was almost flatlining, screaming chronic stress. After about 8 weeks of consistent fuelling and recovery, we saw the morning HRV readings begin to climb, and more importantly, the low-frequency power ratio in her HRV analyses shifted. This wasn’t just about having a higher number; it was about the pattern of heart rate regulation signalling a healthier nervous system balance, a genuine de-escalation of the physiological threat response. It’s like her heart finally took a chill pill.

Too often, we fixate on the symptom and miss the silent conversation the body is trying to have with us.

TL;DR

An endurance athlete restored her menstrual cycle from 18 months of amenorrhea to 6 consecutive cycles in 24 weeks. The intervention focused on comprehensive fuelling, cycle-aware training, and stress reduction to reverse Relative Energy Deficiency in Sport (RED-S). By normalising her energy availability and downregulating her nervous system's threat response, her HPO axis recovered, leading to the return of regular ovulation and a restored LH:FSH ratio.

Where to take this next

This case highlights that symptoms like amenorrhea aren't isolated incidents; they're the body's intelligent, albeit inconvenient, way of communicating a deeper imbalance. Understanding the underlying physiology, rather than just treating the symptom, is key to sustainable change. It's about empowering the body to do what it's designed to do, by creating an environment of safety and abundance.

If you're an athlete struggling with similar issues, or if your body is giving you signals you can't quite decipher, consider diving deeper. We've got resources that can help you rebuild that connection and recalibrate your system.

Dive into specific training at /anchors
Explore 1:1 bespoke guidance at /coaching
Reset your baseline with the free 7-Day Protocol at /reset

Sources

Chrousos, G.P., 2009 — Stress and disorders of the stress system. NIH Reproductive aspects of the stress response: the neuroendocrinology of the stress system
Porges, S.W., 2022 — Polyvagal theory: A science of safety. Frontiers Polyvagal theory: A science of safety