Intermittent Fasting for Women: What the Latest Research Really Says

Andy Turner, ND
Jul 3
4 min read

Over the past few years, intermittent fasting (IF) has become one of the most talked-about health trends. I’ve had many patients ask me about it—some with great results, others feeling confused or depleted. Like so many things in health, the answer isn’t black and white. And for women especially, it’s not always the magic bullet it’s made out to be.

When a patient recently asked me about IF, I promised to do a deeper dive into the newest research. What I found was a fascinating shift in how we’re thinking about fasting for women’s health—and I want to share what I’ve learned with you.

The Appeal (and the Caution)

Intermittent fasting involves cycling between periods of eating and fasting. Common versions include 16:8 (fasting for 16 hours, eating during an 8-hour window) or simply limiting eating to a 10–12 hour window during the day. Some people report better energy, mental clarity, and weight loss. It’s easy to see the appeal.

But historically, many practitioners (myself included) have been cautious about IF for women—especially for those with menstrual cycles, hormone imbalances, thyroid issues, or high stress. And rightly so. Earlier research and clinical experience suggested that IF could disrupt reproductive hormones, affect ovulation, and raise cortisol, the body’s main stress hormone.

What the New Research Says

Recent studies have brought a more nuanced picture. Here’s what we’re learning:

For women with PCOS or high androgens, intermittent fasting—particularly early time-restricted eating—may actually help reduce testosterone and support metabolic health.
For women with regular cycles and lower stress levels, shorter fasting windows (like 12–14 hours overnight) may be well tolerated and even beneficial.
For women with low BMI, thyroid concerns, fertility goals, or high stress, IF still comes with risks. These include disrupted cycles, lower estrogen and progesterone, mood changes, bone loss, and elevated cortisol levels.

In other words, the science is evolving, and the blanket “yes” or “no” approach doesn’t serve us anymore. Instead, we need to ask: Is this the right tool for my body, at this moment in my life?

Early Time-Restricted Eating for PCOS: A Promising Approach

One version of IF gaining traction in the PCOS world is early time-restricted eating (eTRE). This means eating all your meals earlier in the day—usually within an 8–10 hour window, such as 8 AM to 4 PM or 9 AM to 5 PM—and fasting overnight. This rhythm supports the body’s natural circadian clock and seems to improve hormone balance for certain people.

In a 2022 study, women with PCOS who followed an eTRE pattern saw a significant drop in both total and free testosterone, along with an increase in sex hormone-binding globulin (SHBG), a protein that helps clear excess androgens. Insulin sensitivity improved as well—a big deal, since insulin resistance is often a root driver of elevated testosterone in PCOS.

Why does this help? Eating earlier in the day appears to:

Reduce insulin resistance and blood sugar spikes
Lower cortisol levels by reducing evening eating
Support hormonal rhythms that naturally peak in the morning

That said, I don’t recommend eTRE for everyone. Women with lower body weight, disordered eating history, or high stress may find this pattern too depleting. If you’re curious about trying it, start gently—with a 12-hour overnight fast, and work your way toward a 10-hour window if it feels supportive. Be sure to eat enough during your eating window, and prioritize protein, fiber, and healthy fats to keep blood sugar steady.

My Clinical Perspective

In practice, I’ve found that women tend to be more sensitive to blood sugar dips and cortisol spikes—especially in perimenopause, postpartum, or times of emotional stress. This is why I often recommend gentler strategies, like:

A 12-hour overnight fast (for example, finishing dinner at 7 PM and having breakfast at 7 AM)
Syncing your eating rhythms with your menstrual cycle—supporting more nourishment during the luteal phase (after ovulation)
Tracking how you feel—if IF is making you anxious, fatigued, or throwing off your cycle, that’s important information
Making sure meals are protein- and fiber-rich to keep blood sugar stable throughout the day

And most importantly: if you're using fasting as a form of restriction or control, it may be time to pause. Food should nourish your body, not stress it.

Helpful Resources

If you’d like to read more, here are a few recent articles I reviewed that helped shape my perspective:

Bottom Line: Personalization Matters

Like any therapeutic tool, intermittent fasting works best when it's tailored to your individual needs, hormone status, and life context. If you’re curious about whether it’s a good fit for you, I’d love to support you in figuring that out.