Amenorrhea & Cycle Loss

When energy availability drops below approximately 30 kcal/kg lean body mass/day — from undereating, overtraining, or both — the hypothalamus reduces GnRH pulsatility. This suppresses LH and FSH, halting follicular development and estrogen production. The result is functional hypothalamic amenorrhea (FHA). Without estrogen, bone resorption exceeds bone formation — significant bone density loss occurs within months. This is not reversible damage in the short term; bones do not rapidly rebuild. The female athlete triad (low energy availability + menstrual dysfunction + low bone density) has now expanded to the RED-S model, which includes impaired metabolic rate, immunity, cardiovascular function, mood, and coordination.

• Absent menstrual period for 3 or more consecutive months
• Period becoming progressively lighter and shorter over previous months
• Stress fractures or bone pain disproportionate to training load
• Persistent fatigue that does not resolve with rest
• Feeling cold constantly — hypothyroidism is common co-occurrence
• Hair thinning or loss
• Loss of libido and vaginal dryness
• Mood depression, anxiety, difficulty concentrating

• Maintain energy availability above 45 kcal/kg lean body mass/day — especially during high training volume
• Track menstrual cycle — any change in frequency, duration, or flow is an early warning
• Avoid chronic extreme deficits — planned diet breaks every 8–12 weeks are protective
• Adequate dietary fat — 20–30% of calories minimum; fat is required for steroid hormone synthesis
• Rest weeks programmed — deload every 4–6 weeks reduces neuroendocrine stress
• Address psychological drivers of restriction — disordered eating and perfectionism are major risk factors

• Increase energy intake immediately — aim for energy balance or slight surplus until cycle returns
• Reduce training volume (not eliminate) — 20–30% reduction is often sufficient to restore cycle
• Adequate dietary fat and carbohydrate — both are required for GnRH recovery
• Bone density DEXA scan if amenorrhea has lasted 6+ months
• Vitamin D3 2000–4000 IU/day + Calcium 1000–1200mg/day for bone protection
• Gynecologist or sports medicine physician evaluation — do not attempt to restore cycle with OCP as this masks but does not treat the underlying deficit
• Recovery timeline: cycle typically returns in 3–6 months of adequate energy intake. Bone density recovery takes 1–2 years.