Intermittent fasting (IF) has become a popular diet trend, with studies showing benefits like weight loss, improved metabolic health, and lower cholesterol levels. A 2020 study by HealthReporter revealed that 24% of Americans tried IF, making it the most popular diet in the US that year.

While IF offers several health benefits, including convenience and fewer dietary restrictions, it’s not a one-size-fits-all solution—especially for women. Emerging research suggests women might respond differently to IF due to hormonal fluctuations, raising concerns about its long-term effects on female health.

Hormonal Changes and Your Diet

Hormones play a critical role in women’s health, and some studies suggest IF may disrupt them. A 2022 study led by Krista Varady at the University of Illinois found that women on an IF diet experienced a 14% reduction in DHEA—a hormone crucial for ovarian function and egg quality. This is particularly concerning for women who want to maintain reproductive health or are trying to conceive.

However, it’s important to note that the women in this study followed a more extreme version of IF, called the “warrior diet,” with only a four-hour eating window. More moderate IF approaches, like the 16:8 or 14:10 methods, may pose fewer risks, as they provide longer eating windows to meet daily caloric and nutrient needs.

Impact on Testosterone and Metabolism

Testosterone, a hormone important for both women and men, can also be affected by IF. A study published in Nutrients found that both men and women experienced a drop in testosterone levels while practicing IF. This drop could lead to negative health effects, such as reduced metabolic health, muscle mass, and libido. Interestingly, though, participants didn’t report any noticeable side effects, suggesting that short-term IF may not cause harm, but the long-term impact is still unknown.

Insulin Sensitivity and Blood Sugar

While IF has been praised for improving insulin sensitivity and stabilizing blood sugar levels, studies show mixed results for women. In some cases, female subjects experienced worsened insulin sensitivity during fasting periods. This inconsistency highlights the need for further research, as women’s hormonal fluctuations might make blood sugar management more challenging during IF.

Additionally, restrictive IF schedules can lead to major blood sugar fluctuations. Without regular meals, blood sugar dips during fasting periods, followed by spikes during eating windows. This rollercoaster effect can leave women feeling fatigued, hungry, and less energized throughout the day.

The Line Between Fasting and Nutrient Deprivation

While IF can be a tool for managing weight and improving health, it’s crucial to ensure that fasting doesn’t deprive your body of essential nutrients. For women, this can mean the difference between supporting hormonal balance and triggering disruptions that could affect overall well-being.

Starting with a more manageable fasting schedule, like 16:8 or 14:10, allows women to maintain energy and nutrient levels. More extreme schedules, such as the “warrior diet” or the 5:2 method (where you eat normally for five days and fast for two), may be too restrictive and could interfere with hormone regulation and metabolic health.

Who Should Avoid Intermittent Fasting?

Women with certain health conditions may want to avoid IF altogether. If you have a history of eating disorders, thyroid issues, adrenal or autoimmune diseases, or if you’re pregnant or trying to conceive, fasting could do more harm than good. For these women, focusing on a balanced diet of nutrient-dense whole foods is often a safer and more effective approach.

The Bottom Line

Intermittent fasting can offer benefits, but women should approach it with caution. Current research on the long-term effects of IF on female hormones and metabolism is limited, and the potential risks for certain women may outweigh the benefits. Consulting with a healthcare provider or dietitian before starting IF is a smart step to ensure you’re making the best choice for your body.

For now, the best approach is a cautious and balanced one—whether that means starting with a moderate fasting schedule or opting for a different dietary plan that supports overall well-being without the potential risks associated with fasting.