Female health and fasting

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The Huberman Lab has addressed the topics of time-restricted feeding (intermittent fasting) and its implications for female health and fertility, as well as discussing fasting in a broader context. Here are the key insights discussed by and his guests:

  1. Time-Restricted Feeding and Fertility: Time-restricted feeding can have health benefits, but the quality and total calories of food are most important. For females with regular menstrual cycles practicing intermittent fasting, the regularity is a good sign it's not disrupting fertility. However, excessive caloric restriction can cause menstrual periods to cease, impacting fertility 1 2.

  2. Ketogenic Diet in Female Mice: A researcher observed that female mice on a ketogenic diet did not get pregnant while standard diet mice reproduced prolifically. This may be because the diet mimics fasting, and it's not energy-efficient for a body in a fasting state to support creating a baby. Although anecdotal human cases vary, the Ketogenic diet's impact on female hormonal systems requires more controlled studies 3.

    Time-Restricted Feeding

    Andrew discusses the benefits and controversies of time-restricted feeding, also known as intermittent fasting, and its potential effects on fertility. While there is growing evidence that restricting feeding windows can have positive outcomes for health, the most important variable is still the overall number of calories and quality of food sources. However, for those who find it easier to not eat at certain periods of their 24-hour cycle, intermittent fasting can be a convenient way to ensure that total calorie intake is not excessive.

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    How to Optimize Fertility in Males & Females | Huberman Lab Podcast
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  3. Feeding Window Considerations: Women need sufficient leptin signaling from body fat stores to maintain ovulation. Fasting or intense exercise that leads to fasting can reduce important hormones like testosterone in men and affect fertility as the body communicates to the brain whether conditions are favorable for reproduction 4.

  4. Risks of Time-Restricted Eating: Time-restricted feeding can have adverse effects, with female athletes experiencing loss of menstrual cycles and bone health issues when energy intake is drastically reduced—a condition referred to as RED-S (Relative Energy Deficit in Sports). This suggests that a very limited eating window can signal reproductive dysfunction 5.

  5. Fasting and Growth Hormone: Fasting does indeed increase growth hormone levels through the action of ghrelin, a hormone released when hungry. The mechanism involves ghrelin binding to a brain receptor normally engaged by growth hormone-releasing hormone, roughly doubling growth hormone levels in the waking state 6.

  6. Importance of Sleep-Related Fasting: Ideally, feeding should not occur too close to bedtime as sleep-related fasting has special benefits. During sleep, the body undergoes processes that clear out metabolic debris from the brain, aiding in cognition and potentially offsetting dementia. These benefits may be lost if the feeding window is too late in the day 7.

  7. Mitochondrial Health through Dieting: Fasting, intermittent fasting, and fasting mimicking diets aid in mitophagy (the body’s way of cleaning out damaged cells) and stimulate mitochondrial biogenesis. This contributes to preventing aging and supporting mental and physical health. Lowering blood glucose in the brain, which is facilitated by such diets, seems to be a vital factor for neuronal health 8.

The conversations highlight that the impacts of fasting or dieting styles on female health and fertility are complex and can be highly individual. There's emphasis on the importance of maintaining adequate nutrition and not going to extremes that can adversely affect overall hormonal balance and reproductive health. Women interested in fasting should consult with a healthcare provider to understand how it might affect their personal health and fertility.

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