Intermittent Fasting and Women's Health: What You Need to Know

If you pay attention to the health headlines, you’ve probably heard about intermittent fasting - it has been linked with several important health benefits.

But fasting isn’t the same for men and women. If women try fasting but don’t do it properly, it can cause more harm than good. Why? Because women’s bodies are biologically built for fertility and reproduction. Extended periods without food tell the body that now isn’t a good time for reproduction.

You might be thinking, so what? I don’t want to get pregnant now or maybe ever. But fertility isn’t the only concern. Women need to consider that estrogen and progesterone do more in the body than simply get us pregnant. Estrogen helps us with metabolism, weight loss, mood, anxiety and stress, energy, bone density, and cognitive function, to name just a few. If you’re a woman, intermittent fasting can disrupt estrogen balance and throw a wrench in all these essential physiological processes.

But when you know how to use intermittent fasting in a way that is safe for your unique female biochemistry—that is, when you know how to bio-hack intermittent fasting to improve hormone health instead of harm it—you can reap some amazing benefits.

Keep reading. We'll walk you through the benefits, dangers, and how-to of intermittent fasting for women below.

‍Women’s Hormones & Intermittent Fasting

‍Intermittent fasting has been associated with numerous health benefits (more on that below), but it is also linked to hormone disruption in women. Here’s a close-up look at the cascade of hormone imbalances that can start with intermittent fasting.

First, intermittent fasting can disrupt estrogen balance. Estrogen imbalance may show up as:

• Low energy
• Poor glucose control
• Weight gain
• Impaired cognitive function
• Decreased bone density
• Poor muscle tone
• Reduced skin and hair health
• Poorer cardiovascular health
• Infertility

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A disruption in one hormone system in the body can trigger other hormone imbalances. The other major hormone considerations for women when it comes to intermittent fasting are cortisol, the stress hormone, and thyroid hormone. When cortisol is imbalanced, symptoms include:

• Anxiety
• Low energy
• Insomnia
• Feeling wired-but-tired
• Sugar cravings

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When thyroid hormones are imbalanced, symptoms include:

• Weight gain
• Brain fog
• Anxiety
• Depression
• Dry skin
• Dry hair
• Irregular periods
• Trouble regulating body temperature

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So while intermittent fasting may have some benefits, this cascade of negative health effects for women may outweigh any benefit.

‍What is Intermittent Fasting?

‍Simply put, intermittent fasting is going for short or intermediate periods of time without food. This “not eating” window can be as short as 12 hours and include sleep time—for example, you could stop eating at 8:00pm one night and not eat again until 8:00am the next morning and call it a fast—or as long as 16, 20, or 24 hours.

People fast in different ways. Some people try to go 12 or more hours without eating everyday. Others try to go 12 or 16 hours without food a couple days a week. Some people don’t eat for a full 24 hours one day each week.

Why Intermittent Fasting is So Popular

Studies have shown that intermittent fasting may help improve certain health conditions, including:

• Intermittent fasting is associated with improved insulin sensitivity. Insulin sensitivity is an important factor in hormone balance and in overall health
• Intermittent fasting has been linked to reduced body fat
• Meta-analysis also suggests that those to adhere to intermittent fasting regimens don’t compensate by overeating during their designated eating windows. In fact, studies suggest that there is a “carry over effect” of calorie reduction by as much as 20 percent on eating days
• Intermittent fasting may improve health biomarkers associated with Type 2 diabetes
• Intermittent fasting may improve cognitive function and quiet neuroinflammation in the brain
• Intermittent fasting may help dampen stress hormone production in certain situations
• Intermittent fasting may help lower the risk of chronic health conditions

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What Makes Intermittent Fasting Trickier For Women?

‍A woman’s reproductive function is intricately connected to her metabolic function, and vice versa. So anytime a woman’s body gets a “starvation signal” from her environment (like not eating for a stretch of time), it goes into preserve and protect mode, where it holds onto weight (to survive the famine), increases production of the hunger hormones ghrelin and leptin (so that you feel famished and rush to get food ASAP), and slows down non-essential functions like reproduction (so you can keep yourself alive and not waste energy on growing a baby).

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Animal studies bear this out: in one study, female rats who engaged in intermittent fasting for 12 weeks had smaller ovaries and experienced more insomnia than male mice. But the researchers found that these changes started in as soon as two weeks after the female mice started intermittent fasting.

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How Women Can Use Intermittent Fasting Safely

‍This doesn’t mean women have to miss out on the benefits of intermittent fasting. Instead, we recommend that women follow some simple rules when it comes to intermittent fasting. This will help you tap into the many benefits associated with intermittent fasting while sidestepping the risks.

• Don’t fast on consecutive days
• Instead, pick no more than two or three non-consecutive days in a week to practice intermittent fasting
• Don’t fast for more than 12 or 13 hours at a time. Going any longer can trigger a negative hormonal cascade
• Don’t do intense workouts on fasting days
• Don’t fast when you’re bleeding
• During your eating window, choose the best diet for your hormonal health
• If you give this slow and steady approach to intermittent fasting a try for a couple months and feel great, you can consider going for a longer window of time each day without eating (up to 16 hours), but pay close attention to how you feel and drop back to a smaller window—or stop intermittent fasting all together—if you start experiencing symptoms of hormone imbalance.

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If you start to experience symptoms of hormone imbalance while intermittent fasting, or if the hormone imbalance symptoms you already experience get worse, stop fasting right away.

‍These symptoms include:

• Your period becomes irregular or stops
• You start having problems sleeping or falling asleep
• You notice changes in metabolism and digestion
• You feel moody or experience brain fog
• You notice negative changes in how your hair and skin looks
• You’re always cold

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Do NOT Try Intermittent Fasting If...

• You have a history of eating disorders
• You’re pregnant or are trying to conceive
• You have trouble falling asleep, staying asleep or trouble waking up in the morning
• You have adrenal fatigue
• You are currently dealing with PMS, PCOS, Fibroids, Endometriosis or other diagnosed hormonal issues

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Always remember, that once you have the right information about how your body really works, you can start making health choices that finally start to work for you! You can do this – the science of your body is on your side!