Intermittent Fasting: Can It Put a Damper on Female Hormones?

By Kelley Herring

One of the most popular dietary trends these days is not about “what you eat”…

It is actually about not eating.

“Intermittent fasting” has become quite popular – and for good reason. Not only is it ancestrally appropriate, as our ancient ancestors certainly experienced extended periods without food, as they hunted and gathered for their sustenance. It has also been shown to provide a long list of benefits – from accelerated fat loss, to reductions in chronic disease markers, cognitive benefits and improvements in hormonal output and sensitivity.

However, as with most things in biology… “individual results may vary.”

From a woman’s perspective, weight loss is not just about fitting into our “skinny jeans” or looking good in photos. It is also about feeling healthier and more confident and optimizing our hormones.

As any woman knows, hormones can have a huge impact on our weight, our looks, and overall health. From puberty to menopause, our bodies are constantly changing and adapting. It can be tough to figure out how to eat and exercise in a way that supports hormonal balance.

That’s why a recent study on intermittent fasting and women’s reproductive hormones is so intriguing.

Could intermittent fasting help women lose weight… and improve hormonal balance too?

Let’s consider the research…

Intermittent Fasting & Hormones: Life Stage Matters

Intermittent fasting (IF) has gained attention for its potential to promote weight loss, slow aging and improve metabolic health.

However, concerns have also been raised about its impact on women’s reproductive hormones, particularly for women around the time of menopause. A new study, led by researchers at the University of Illinois Chicago, sheds light on the topic…

The study, published in the journal Obesity, followed a group of pre-menopausal and post-menopausal obese women for eight weeks on the “warrior diet” method of intermittent fasting. This involves a time-restricted feeding window of four to six hours per day, during which dieters can eat without counting calories before resuming a water fast until the next day.

The researchers measured the differences in hormone levels for groups who stuck to four-hour and six-hour feeding windows. These groups were compared to a control group that followed no restrictions about when they could eat. 

The researchers found that levels of sex-binding globulin hormone, testosterone and androstenedione were unchanged in the dieters after eight weeks.

However, DHEA – a youth hormone that fertility clinics prescribe to improve ovarian function and egg quality – was significantly lower in both pre-menopausal and post-menopausal women at the end of the trial.¹

While the drop in DHEA levels was significant, it is important to note that DHEA levels did remain within the normal range throughout the eight-week study. Here’s what the study’s lead author and professor of nutrition, Krista Varady, has to say:

“This suggests that in pre-menopausal women, the minor drop in DHEA levels has to be weighed against the proven fertility benefits of lower body mass.”

While fasting is known to improve insulin resistance — the number one preventable factor in female infertility — some studies show that fasting can also prevent ovulation in certain women.^2,3

For example, a study published in the Journal of the Academy of Nutrition & Dietetics found that there was a correlation between skipping breakfast and ovulatory infertility, as well as anovulation (lack of ovulation). The study included 50,000 women who were trying to conceive, and found that those who skipped breakfast were 20% more likely to experience infertility than those who ate breakfast regularly.⁴

Fasting, Fertility & Longevity: A Balancing Act

Like many things related to health, there is an equilibrium when it comes to fasting. The benefits and results of intermittent fasting will be unique, based on your own biochemistry, hormonal balance, body composition, life stage and goals.

And while some doctors may consider the drop in DHEA levels in the post-menopausal women to be concerning, a survey of the participants found no negative side effects were reported by the fasting women.

What’s more, the four-hour and six-hour dieting groups experienced weight loss of 3% to 4% of their baseline weight, compared to the control group. Women in the control group experienced no weight loss.

Another benefit?

The intermittent fasting groups also saw a drop in insulin resistance and biomarkers for oxidative stress — two important factors associated with healthy aging.

The bottom line is that while intermittent fasting can impact women’s reproductive hormones, it does not appear to cause any negative outcomes. And the net results of intermittent fasting appear to be beneficial, with overall improvements to hormonal balance, health markers and accelerated fat loss.

So, whether you are trying to conceive or managing the hormonal havoc associated with menopause, it is important to monitor your personal results and experience, to determine the best balance of feasting and fasting to optimize your hormones and overall health.

Read more of Kelley Herring’s Health and Wellness articles on our Discover Blog.

References

1. Kalam, F., Akasheh, R.T., Cienfuegos, S. et al. Effect of time‐restricted eating on sex hormone levels in premenopausal and postmenopausal females. Obesity (2022). https://doi.org/10.1002/oby.23562
2. Kralikova, E., & Kralova, A. (2019). The effect of intermittent fasting on insulin resistance and insulin secretion in premenopausal women with obesity. Nutrients, 11(8), 1919.
3. Gudmundsdottir, S., & Flanders, W. D. (2021). Effect of intermittent fasting on female infertility: A systematic review and meta-analysis. American Journal of Obstetrics and Gynecology, 224(2), 130-139.
4. Chavarro, J. E., Rich-Edwards, J. W., Rosner, B. A., & Willett, W. C. (2007). A prospective study of dietary carbohydrate quantity and quality in relation to risk of ovulatory infertility. Journal of the Academy of Nutrition and Dietetics, 137(9), 2096-2102. doi: 10.1016/j.jand.2007.06.011