Dipla · Hormones (Athens, Greece) 2021 · narrative review · n=?

Relative energy deficiency in sports (RED-S): elucidation of endocrine changes affecting the health of males and females.

Cited 162 times in the scientific literature.

Level 5 - mechanism / opinion, no new human data

Narrative review detailing physiological and endocrine mechanisms without primary human data or systematic synthesis.

PubMed 32557402 · doi:10.1007/s42000-020-00214-w · record verified 2026-08-28

What was done

This narrative review describes the physiological mechanisms and endocrine alterations associated with low energy availability and relative energy deficiency in sport (RED-S) across male and female athletes.

What was found

The abstract reports no quantitative values, sample sizes, or statistical metrics. It describes qualitative pathophysiological pathways: low energy availability reduces hypothalamic gonadotropin-releasing hormone pulsatility, blunting luteinizing hormone and follicle-stimulating hormone release. In females, this causes hypoestrogenism, functional hypothalamic amenorrhea, and reduced bone mass. In males, it lowers testosterone and impairs bone health. Low energy availability also alters thyroid hormone pathways, leptin levels, carbohydrate metabolism, the growth hormone/insulin-like growth factor-1 axis, and autonomic nervous system tone.

Why it matters

This review emphasizes that energy deficiency affects both male and female athletes across multiple physiological systems, expanding clinical focus beyond the traditional female athlete triad.

Limits

The abstract contains no primary data, statistical estimates, or systematic literature search methodology. Details regarding diagnostic criteria, severity thresholds for energy deficits, and long-term clinical outcomes are not provided.

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