Dry fasting, which involves abstaining from both food and water for short periods, is emerging as a potential tool for enhancing fertility in both sexes. While research is still developing, evidence suggests it can positively influence hormone levels, particularly for those with infertility linked to metabolic issues like obesity, insulin resistance, polycystic ovary syndrome (PCOS) in women, or hypogonadism in men. By resetting the endocrine system and boosting insulin sensitivity during refeeding, dry fasting may offer a net benefit.
Maria Velissariou
A low energy state correlated with less sperm motility
✉Correspondence to: Einat Haikin Herzberger, eintahaikintauex.tau.ac.il ✉Corresponding author.
Keep in mind that fasting itself is a low-energy state that can slow things down, including sperm motility. Still, the magic lies in the refeed and subsequent hormone normalization, and FH and testosterone boost.
LH, FSH, SHBG, and Testosterone levels during refeeding after a fast
- FSH (Follicle-Stimulating Hormone): Pre: 1.2 mU/L (low, below normal 1.5-12.4 mU/L, suppressed gonadotropins during fasting). Post: 4.7 mU/L (normalized, mid-range). Change: +290% increase; supports spermatogenesis rebound.
- Testosterone: Pre: 15.6 nmol/L (mid-normal, 8.6-29 nmol/L, often dips in prolonged fasting). Post: 30.1 nmol/L (high-normal, slight exceedance possible transient). Change: +93% increase; enhances libido, sperm quality, and muscle recovery.
- Oestradiol (Estradiol): Pre: 70.8 pmol/L (19 pg/mL, low-normal for men <150-200 pmol/L). Post: 204 pmol/L (55 pg/mL, elevated above typical male upper limit ~150 pmol/L). Change: +188% increase; likely from aromatization of rising testosterone—beneficial for bone/sperm but monitor for excess (e.g., gynecomastia risk).
- SHBG (Sex Hormone-Binding Globulin): Pre: 81 nmol/L (elevated, 10-57 nmol/L, common in fasting due to low insulin). Post: 32 nmol/L (normalized, mid-range). Change: -60% decrease; increases free testosterone bioavailability, aiding fertility.
- DHEAS (Dehydroepiandrosterone Sulfate): Pre: 11.6 μmol/L (assuming μmol/L, as mmol/L is implausibly high; high-normal 1.9-13.4 μmol/L, adrenal stress response in fasting). Post: 4.3 μmol/L (mid-normal). Change: -63% decrease; normalization reduces excess androgens, balancing hormones.
These hormonal shifts promote fertility restoration: restored follicle-stimulating hormone (FSH) and testosterone levels can boost sperm production and motility in men, while lower sex hormone-binding globulin (SHBG) and dehydroepiandrosterone sulfate (DHEAS) enhance free hormone availability and reduce androgen excess, a common issue in PCOS.
*Correspondence: varadyuic.edu; Tel.: +1-312-996-7897
Studies on related practices like intermittent or Ramadan fasting highlight improvements in women's reproductive health, including better menstrual regularity, reduced androgens (such as a 9% testosterone drop in PCOS cases), and enhanced ovulation.
However, risks include temporary hormone disruption during the fast (e.g., suppressed FSH and testosterone), so benefits typically emerge post-refeeding.
This is why you will keep on hearing that the magic of the fast is in the refeed. You need to nurture the body after the fast by giving it tons of fuel and energy for restoration depending on where you are in your health journey. If you're early in it and not fighting symptoms of fatigue, you can refeed ketogenically, but otherwise you will need to fuel with much more carbohydrates to get all the benefits of the stem cells and insulin sensitivity long term.
