Scientists have discovered that time-restricted fasting might cause fertility problems.
Intermittent fasting, or “time-restricted eating,” is often praised for its weight loss perks and benefits for conditions like polycystic ovary syndrome (PCOS).
But here’s a twist – did you know it might affect egg and sperm quality?
WHAT IS INTERMITTENT FASTING?
Intermittent fasting is more about when you eat than what you eat. It involves alternating between eating and fasting periods, such as skipping meals on certain days or eating only during specific hours each day (time-restricted eating). The idea is to give your body a break from constant digestion, allowing it to burn fat, repair cells, and balance blood sugar levels.
HOW DOES IT WORK?
Intermittent fasting involves cutting calories on certain days (such as eating 500 calories every other day) or limiting eating to specific windows each day. A popular method is the 16:8, which involves fasting for 16 hours (only water, coffee, or tea is allowed) and eating during an 8-hour window, often from 12 pm to 8 pm. Other variations include 18:6, 20:4, or even one meal a day. It’s all about giving your body extended breaks from food to optimize metabolism and repair processes.
WHAT ARE THE BENEFITS OF INTERMITTENT FASTING?
Many studies suggest that it might be beneficial for managing weight and conditions like PCOS, obesity, diabetes, and heart disease. However, the results aren’t always clear-cut – some studies report conflicting results.
RECENT FINDINGS ON FERTILITY
Scientists have discovered that time-restricted fasting might cause fertility problems. A study on zebrafish showed that while females produced more eggs during fasting, these eggs were of lower quality, resulting in poorer quality offspring. Males also experienced a drop in sperm quality. This result may not be that surprising, as organisms generally focus more on survival and less on reproduction during periods of dietary restriction.
Though zebrafish are a popular model organism often used in research (they share about 70% of their genes with humans), these results require more investigation to understand how fasting affects human fertility, including egg and sperm quality, and how long recovery might take. Some negative effects on egg and sperm quality were still observed even after normal eating resumed.
HOW FASTING MAY IMPACT FERTILITY IN WOMEN
For most women, especially those who are active and healthy, intense fasting practices (like a 20-hour fast) can be harmful. For instance, skipping breakfast after a long overnight fast can spike cortisol (the stress hormone usually peaks about 30 minutes after waking). Combined with coffee on an empty stomach, this can disrupt essential reproductive hormones like thyroid, LH, and estrogen. Eating in sync with our body’s natural circadian rhythm is crucial for maintaining a healthy hormone balance, primarily by consuming food early in the day when cortisol is highest. This can prevent excessive stress (such as overactivation of the sympathetic nervous system, which triggers the “fight or flight” response) and avoid blood sugar imbalances. This approach becomes even more important for women approaching peri-menopause, as hormonal fluctuations and cortisol levels further increase with age.
SUPPLEMENTS THAT MAY SUPPORT FERTILITY:
Beyond your standard prenatal packed with essentials like B vitamins, including methylfolate (the active form of folate, immediately usable by the body; conversion of folate or folic acid may be difficult for individuals with a genetic mutation [e.g., MTHFR polymorphism]), choline, vitamin D, selenium, zinc, etc., there are other key nutrients that support mitochondrial and metabolic health – especially crucial for women with PCOS.
- Alpha-lipoic acid (ALA)
- Berberine
- Coenzyme Q10 (CoQ10)
- Carnitine
- Myo-inositol
- N-acetylcysteine (NAC)
- Omega-3 fatty acids
FINAL THOUGHTS
Intermittent fasting can be beneficial, but it’s not a one-size-fits-all solution. Keep in mind that fasting might not be right for everyone – especially for individuals with specific health conditions such as type 1 diabetes or pregnancy, and for women in their reproductive years without conditions like PCOS. Always check in with your health care practitioner before diving into fasting to ensure it’s the right choice for you.
