Female Athlete Health Panel

Relative energy deficiency in sport (RED-S) is a syndrome that occurs when caloric intake is insufficient to support both the demands of training and normal physiological function. It was previously described primarily as the female athlete triad (low energy availability, menstrual dysfunction, and low bone density), but the updated RED-S framework recognises it affects male athletes too. In females, the hallmark sign is hypothalamic amenorrhoea: the brain suppresses reproductive hormone output to conserve energy. Blood tests that show suppressed LH, FSH, and oestradiol in a training female athlete provide objective evidence of hormonal disruption consistent with RED-S and prompt appropriate intervention.

Menstruation creates a baseline iron loss that male athletes do not experience. Female athletes who train at moderate to high volumes are losing iron through sweat, gut microdamage from exercise, and menstrual flow simultaneously. Even women with regular, relatively light periods can deplete iron stores over a training season if dietary intake is insufficient. Plant-based female athletes face additional risk because non-haem iron from plant sources is far less bioavailable than haem iron from red meat. Ferritin testing is the most sensitive early warning tool; we recommend targeting ferritin above 30 micrograms per litre for optimal performance.

The hypothalamus monitors energy availability as a signal of whether conditions are suitable for reproduction. When energy intake is insufficient relative to energy expenditure — even in the absence of a clinical eating disorder or low body weight — the hypothalamus reduces pulsatile gonadotrophin-releasing hormone (GnRH) secretion, which in turn suppresses LH and FSH from the pituitary. Without adequate LH and FSH, the ovaries do not cycle normally, and oestradiol production falls. The result is irregular periods or full amenorrhoea. This is not a normal training adaptation; it is a physiological stress signal requiring nutritional and often psychological intervention.

Oestrogen is one of the primary hormones regulating bone remodelling, specifically inhibiting osteoclast (bone-resorbing cell) activity. When oestradiol is suppressed by hypothalamic amenorrhoea, bone resorption accelerates unchecked. This leads to reduced bone mineral density and increased stress fracture risk, particularly in weight-bearing bones such as the tibia, metatarsals, and femoral neck. Unlike the bone loss of menopause, which tends to be gradual and occurs in older women, athlete-related bone loss can be rapid and occur in young athletes who might otherwise expect peak bone mass accrual.

Yes, period loss during training should never be dismissed as normal or trivial. It is a clinical red flag indicating that your body is under significant physiological stress. Beyond bone health and hormonal consequences, loss of menstruation is associated with impaired immune function, increased injury risk, cardiovascular changes, and psychological sequelae. The appropriate response is not to continue training through it, but to work with a sports physician, dietitian, and psychologist if needed to restore energy availability and hormonal function. Blood testing to confirm the hormonal picture is the recommended first step.