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The effects of intermittent fasting on fertility are complex and multifaceted, varying between genders and depending on the duration and timing of fasting. While intermittent fasting may offer benefits for certain conditions like PCOS in females, it could also pose risks to fetal development during pregnancy and impair male reproductive health by altering hormone levels and reducing sperm count. More research is needed to fully understand these effects and to provide clear guidelines for individuals considering intermittent fasting, especially those concerned about fertility.
Intermittent fasting (IF) has gained popularity as a dietary strategy for weight loss and metabolic health. However, its impact on fertility remains a topic of concern and debate. This article explores the effects of intermittent fasting on reproductive health in both males and females, drawing on findings from recent research studies.
Effects on Female Fertility
Hormonal Changes
Intermittent fasting has been shown to influence reproductive hormone levels in females. A review of human trials indicated that intermittent fasting decreases androgen markers such as testosterone and the free androgen index (FAI) while increasing sex hormone-binding globulin (SHBG) levels in premenopausal females with obesity. However, it did not affect estrogen, gonadotropins, or prolactin levels1. These hormonal changes could have mixed implications for fertility. For instance, reducing androgen levels might benefit women with polycystic ovarian syndrome (PCOS), potentially improving menstruation and fertility.
Pregnancy and Fetal Development
The impact of intermittent fasting during pregnancy has also been studied. Research on pregnant Wistar rats showed that maternal intermittent fasting led to reduced placental weight and birth weight, indicating fetal growth restriction. The study also found altered placental metabolite profiles and reduced transplacental amino acid transport, which could negatively affect fetal development2. Another study on mice suggested that long-term pre-pregnancy intermittent fasting could deteriorate offspring metabolism by suppressing hepatic mTORC1 signaling, leading to increased adiposity and impaired glucose metabolism in adult offspring4.
Effects on Male Fertility
Hormonal and Testicular Health
Intermittent fasting appears to have a significant impact on male reproductive hormones and testicular health. In a study involving adult male rats, intermittent fasting combined with a ketogenic diet improved oxidative status and enhanced spermatogenesis, suggesting potential benefits for male fertility3. However, other studies have reported reductions in testosterone levels and alterations in reproductive hormones such as LH and FSH during fasting periods1 5 6. These hormonal changes could potentially impair spermatogenesis and reduce sperm count, as observed in fasted male rats6.
Short-term Fasting Effects
Short-term fasting in obese men resulted in decreased serum FSH concentrations and reduced pituitary responsiveness to FSH and LRH. Serum testosterone levels also decreased significantly during fasting, although urinary excretion of LH and FSH increased5. These findings suggest that short-term fasting can disrupt hormonal balance, potentially affecting fertility.
Is intermittent fasting bad for fertility?
Gurcharan Kaur has answered Uncertain
An expert from Guru Nanak Dev University in Mental Health, Women’s Health, Global Health
Yes, the reproductive system is sensitive to change in energy status of the body. Nutritional infertility is very common in societies where women fail to eat enough to match their energy expenditure and such females often present as clinical cases of anorexia nervosa. But these are cases of severe dietary restriction. I think that dietary/caloric restriction in moderation by intermittent fasting regimen does not adversely effects fertility. It is recommended that skipping one meal at least 2-3 days a week (preferably dinner) to observe 12-14 hrs gap between meals is best strategy as this seems to be easily applicable in routine life. But at the same time, pregnant females and people having metabolic diseases should take advice of their physician.