Effect of Intermittent Fasting on Reproductive Hormone Levels in Females and Males: A Review of Human Trials
Cienfuegos S, Corapi S, Gabel K, Ezpeleta M, Kalam F, Lin S, Pavlou V, Varady KA · 2022 · Nutrients
DOI: 10.3390/nu14112343View source ↗
“Intermittent fasting decreases androgen markers (testosterone and free androgen index) while increasing sex hormone-binding globulin levels in premenopausal females with obesity.”
Summary
This Nutrients review is the first to synthesize specifically what human trials of intermittent fasting (not animal work, not religious fasting) show about sex-hormone shifts in women and men. The authors identified seven human trials total: five testing time-restricted eating, one testing a 5:2 protocol, and one studying meal timing. Their headline findings for premenopausal women with obesity: intermittent fasting reduces testosterone and the free androgen index, and increases sex hormone-binding globulin — particularly when the eating window is restricted to earlier in the day. Estrogen, luteinizing hormone, and follicle-stimulating hormone showed no statistically meaningful change in the trials reviewed. In men, intermittent fasting reduced total and free testosterone in some studies, with implications for libido and lean-mass maintenance that the authors flag as concerning at longer protocol durations. The honest summary: female reproductive hormone effects are real but modest, mostly favorable for PCOS-spectrum profiles, and depend heavily on eating-window timing.
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Entries that reference this one
- ExtendsEnergy availability, not body fatness, regulates reproductive function in womenLoucks AB · 2003
Loucks 2003 established the canonical energy-availability threshold (20–30 kcal/kg LBM/day) for women's reproductive function; Cienfuegos 2022 reviewed how time-restricted intermittent fasting protocols specifically affect reproductive hormones — operating within or below the threshold Loucks identified.
- ExtendsThe impact of intermittent fasting on fertility: A focus on polycystic ovary syndrome and reproductive outcomes in Women — A systematic reviewVelissariou M et al. · 2025
Cienfuegos 2022 reviewed IF effects on reproductive hormones broadly (women and men, mostly healthy populations); Velissariou 2025 narrows the focus to PCOS specifically and finds substantive menstrual-cycle and androgen improvements.
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Not medical advice. This page summarizes primary research. It is not a substitute for consultation with a qualified clinician. See safety for exclusion criteria.