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Glossary

Functional hypothalamic amenorrhea

Defined in topic 32

Periods stopping because the reproductive axis has shut down under low energy availability. It can occur without visible weight loss and needs clinical assessment.

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Where this comes from

In the reference topic that owns this term

Reference topic 32, The Reproductive Paradox, states the mismatch as a card: what the system evolved to expect, what it gets instead, and what happens in the gap.

Mismatch card

What it expects

Steady energy availability, first births while fertility is at its peak, kin nearby to subsidize weaned children, and a lifetime of relatively few ovulatory cycles (Topic 22).

What it gets

Energy surplus or deficit rather than balance, a mean first birth at 27.5 in the United States, grandparents in other cities, and an industrial chemical environment nobody has fully characterized.

What happens in the gap

Ovulation stops in women who look healthy, obesity disturbs the same loops from the opposite side, sperm counts and testosterone drift downward across cohorts, and the biological window opens and closes on a schedule the social one ignores.

The full card, and the topic behind it

What that chapter recommends

3 of the 5 graded recommendations in Reference topic 32, strongest evidence first. How the grades work.

  1. Keep energy availability adequate

    StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

    Periods that become irregular or stop during heavy training or dieting signal that intake is not covering output. The disruption can occur without weight loss.

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  2. Learn the timeline early, and treat it as planning information

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    Fertility declines with age in both sexes and more steeply for women after the mid-30s. Anyone thinking about children benefits from knowing that before the decision is urgent.

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  3. Aim for a stable, moderate body composition in both sexes

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    Excess body fat disturbs the same hormonal loops from the other direction, through aromatase activity and insulin signaling. It affects ovulation in women and testosterone and sperm in men.

    Read it in full

Related terms

The argument behind this term, its studies and its notes are in Reference topic 32 of the reference library. The book gives the practical version. Get the book.