Between 1972 and 2019, the average testosterone level in men dropped by 54%, which equals more than a 1% decrease each year.
See the scientific wording
Average testosterone levels in men declined by 54% between 1972 and 2019, corresponding to an average annual decline of more than 1%.
There's disagreement
ObservationalThe 3 studies we reviewed point in different directions — there's no clear consensus.
What the research says
3 studies reviewedSupporting (1)
Cross-Sectional StudyHuman
The study found that older, overweight men have 54% less testosterone than younger, lean men — which matches the 54% drop claimed over decades. This suggests testosterone naturally falls as men age, supporting the idea that average levels have dropped over time.
Contradicting (2)
RETHINKING LOW TESTOSTERONE IN OLDER MEN: ASSOCIATION WITH OBESITY RATHER THAN AGING.
Cohort StudyHuman2025
This study found that older men today don’t have lower testosterone than younger men — it’s about how much belly fat they have, not how old they are. So it doesn’t support the idea that testosterone has been dropping steadily for decades.
Cross-Sectional StudyHuman2020
The study looked at how testosterone changes as men get older, not how testosterone levels changed in all men from 1972 to 2019. It found only small yearly drops in active testosterone, not the huge 54% drop claimed.
Quality-weighted scoring: we follow the GRADE framework — each study is rated High, Moderate, Low, or Very Low based on study design, methodology rigor, and risk of bias. A single high-quality RCT can outweigh several weaker observational studies.
Scores reflect study quality, not just count.
As men get older and gain body fat, their fat tissue grows larger and sends signals that reduce testosterone production in the testes. At the same time, the brain's control center for testosterone stops signaling the testes as strongly. This causes testosterone levels to drop steadily over time.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting, 2 contradicting studies
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