hormones
Relative Energy Deficiency in Sport (RED-S)
A syndrome of impaired physiological function caused by chronic under-fueling in athletes.
RED-S describes the downstream effects of sustained calorie deficits in athletes — suppressed menstrual function, reduced bone density, blunted performance, immune impairment, and endocrine disruption. It replaces the older "Female Athlete Triad" and affects both sexes. The fix is unglamorous: eat more, especially around training, and restore energy availability to ≥45 kcal/kg lean mass/day.