【For Those Who Struggle Before Their Period】Can Fasting Ease PMS? Eating Rules for Hormone Balance and How to Fast Through Each Phase of Your Cycle

Have you ever wondered, “Why do I feel this awful every single month before my period?”

Irritability, bloating, headaches, sleepiness, a swollen belly: PMS symptoms are really tough, aren’t they?

In fact, the root causes of much PMS and period pain are hormonal imbalance and chronic inflammation.

And what can tackle both of these directly is “combining fasting with the right diet.”

Fasting may sound like it’s all about willpower, but used wisely in sync with your menstrual cycle, it can become a reliable ally.

In this article, I’ll explain in an easy-to-follow way how to work fasting into your menstrual cycle, along with eating rules that help balance your hormones.

I’ll also go over why fasting gets harder before your period and the precautions that help you avoid overdoing it.

Why Can Fasting Ease PMS and Period Pain?

PMS Is Caused by Excess Estrogen and Inflammation

PMS (premenstrual syndrome) is a condition where mental and physical discomfort appears about 3 to 10 days before your period and eases once your period starts.

Before your period (the luteal phase), the balance between estrogen and progesterone is easily disrupted, and PMS symptoms become stronger when estrogen becomes relatively excessive.

You can picture the two hormones supporting your well-being by balancing each other like a seesaw.

In addition, chronic inflammation from modern diets triggers overproduction of prostaglandins (inflammatory substances), which makes period pain worse.

Prostaglandins are also substances that make the uterus contract to push menstrual blood out.

When too many are produced, the uterus clenches tightly and the pain becomes more intense.

Eating too many carbs, processed foods, and trans fats often fuels this inflammation.

How Fasting Works on Hormone Balance

When you fast, the first thing that happens is that insulin in your blood drops.

Insulin is the hormone that works to lower blood sugar.

When insulin stays high, male hormones (androgens) become excessive and hormone balance is disrupted.

Lowering insulin through fasting lays the groundwork for restoring hormonal stability.

Also, the liver’s detox function, which is boosted during fasting, helps clear out estrogen that the body has finished using.

The liver works like a “waste-processing plant” that handles hormones that have done their job and sends them out of the body.

When estrogen is excreted instead of being reabsorbed into the body, premenstrual bloating, irritability, and breast tenderness are relieved.

Once the bloating and irritability calm down, the days before your period become much easier to get through.

On top of that, the anti-inflammatory effect of fasting curbs the overproduction of prostaglandins and eases period pain itself.

Among the people around me, I’ve heard several women who started fasting say things like “my irritability before my period went down” and “I no longer need painkillers for period cramps.”

Overseas, a randomized controlled trial was also conducted on women with PMS who had obesity or were overweight, examining how fasting that reduces food intake every other day affects PMS symptoms.

However, results vary from study to study, and it’s not yet at the stage where a conclusion has been reached.

It’s best to think of fasting not as “a way to cure PMS,” but as one habit that builds a foundation for a body where hormones can balance more easily.

PMS and Period Pain Are Different Things

PMS and period pain tend to be talked about as if they’re the same, but in fact they occur at slightly different times and through different mechanisms.

PMS is mental and physical discomfort that appears before your period starts, and it’s characterized by easing once your period begins.

Period pain, on the other hand, refers to the pain caused by the uterus contracting during your period.

Because both are linked to hormones and inflammation, some people may feel changes in both by rethinking their diet and fasting.

However, if the pain is so severe that painkillers don’t work, there may be an underlying condition such as endometriosis, so please see a gynecologist.

5 Eating Rules for Balancing Your Hormones

1. Cut Back on Sugar and Refined Carbohydrates

Blood sugar spikes cause insulin to surge and are one of the biggest causes of hormonal imbalance.

Suddenly feeling sleepy or irritable after eating something sweet is often caused by your blood sugar swinging up and down.

By cutting back on white rice, bread, sweet buns, and sugary snacks and centering your diet on brown rice, whole grains, and vegetables, your blood sugar stabilizes and PMS symptoms are more likely to improve.

Especially in the two weeks before your period (the luteal phase), just being mindful of keeping carbs down can make a difference.

When you crave something sweet, choose foods that don’t spike blood sugar easily, such as nuts, fruit, or yogurt.

2. Use Dietary Fiber to Prevent Estrogen from Being Reabsorbed

When your gut bacteria are out of balance, estrogen that should be excreted gets reabsorbed in the intestines.

It’s like trash you’ve taken out coming back into the house before the garbage truck picks it up.

Actively eating dietary fiber (vegetables, beans, brown rice, and so on) supports your gut’s ability to eliminate waste, so excess estrogen can be properly flushed out of your body.

Aim for at least 25 g of dietary fiber a day, and make a point of including vegetables at every meal.

3. Calm Inflammation with Omega-3 Fatty Acids

Omega-3 fatty acids, found in abundance in oily fish (mackerel, sardines, Pacific saury), walnuts, and flaxseed oil, help calm inflammation and prevent the overproduction of prostaglandins.

Many people find that simply eating oily fish three or more times a week changes how intense their period pain is.

Using canned mackerel or canned sardines makes it easy to add them even on busy days.

On the other hand, the oils common in chips and fried foods tend to fuel inflammation, so it’s safer to go easy on them before your period.

4. Make a Point of Getting Magnesium

Magnesium relaxes tension in the uterine muscles and helps reduce PMS irritability, headaches, and bloating.

It’s found in abundance in spinach, nuts, dark chocolate, tofu, and more.

Make a special effort to get it in the 1 to 2 weeks before your period.

Calcium is also a nutrient that has been linked to PMS, so make sure you don’t fall short by eating small fish, dairy products, komatsuna (Japanese mustard spinach), and so on.

5. Support Your Gut Environment with Fermented Foods

Gut bacteria are deeply involved in estrogen metabolism.

Eating fermented foods such as yogurt, miso (fermented soybean paste), natto (fermented soybeans), and kimchi every day supports your gut environment and your hormone metabolism.

If bloating is a concern for you, be careful not to overdo salty pickles and processed foods.

Eating potassium-rich foods like bananas, avocados, and seaweed at the same time also makes it easier to flush excess salt out of your body.

A Fasting Schedule Matched to Your Menstrual Cycle

The 4 Phases of the Menstrual Cycle and Fasting Intensity

A woman’s menstrual cycle is roughly divided into 4 phases.

Because your body is in a different state in each phase, it’s important to match your fasting intensity to it.

Cycle length varies from person to person, so treat the number of days only as a rough guide.

Using an app that lets you log your periods makes it easier to tell which phase you’re in right now.

If you track your basal body temperature, you can also use the time when your temperature rises as a guide to your luteal phase.

The Follicular to Ovulatory Phase Is the Time to “Go for It” with Fasting

The follicular phase, from the end of your period until ovulation, is a time when estrogen increases and both body and mind tend to feel energetic.

During this time, you’re relatively resistant to hunger, so 16-hour fasting is easier to practice.

If you compare it to the seasons, it’s like “spring,” when your body moves most easily.

If you’re not used to fasting, starting during this time makes you more likely to succeed.

Why You Should Ease Up on Fasting During the Luteal Phase

During the luteal phase, the two weeks before your period, progesterone raises your metabolism and makes you hungrier.

Pushing yourself to fast during this time can raise cortisol (a stress hormone) and actually disrupt your hormone balance.

Fasting isn’t something to “push through”; it’s something to “adjust to your body”.

Especially during the luteal phase, set shorter fasting times and focus on making up for it with the quality of your meals.

Among the many women who fast that I’ve talked with, the one who felt the biggest benefit made a simple adjustment: “shortening her fast only before her period.”

During Your Period, Prioritize “Getting Enough Iron”

During your period, iron is lost along with menstrual blood, so it’s a time when you’re prone to anemia.

A lack of iron can lead to fatigue, headaches, feeling cold, and trouble concentrating.

During this time, rather than cutting back on food by fasting, make sure to get plenty of iron from red meat and fish, clams, komatsuna (Japanese mustard spinach), beans, and so on.

Eating them together with vegetables and fruits rich in vitamin C helps your body absorb iron.

Adding warming miso soup or other soups to your meals is also recommended.

Getting good nutrition during your period prepares you to feel energetic during the next follicular phase.

Why Fasting Gets Harder Before Your Period, and What to Watch Out For

Blood Sugar Is Easily Disrupted During the Luteal Phase

While fasting may help with PMS, doing it the wrong way can backfire.

The luteal phase before your period is said to be a time when progesterone makes insulin work less effectively, so blood sugar is easily disrupted.

When blood sugar drops suddenly, you’re more likely to feel intense hunger, sugar cravings, and irritability.

The common struggle of “I can’t stop eating chocolate before my period” is tied to this kind of bodily mechanism.

Fasting for long stretches during this time can make your blood sugar swings even bigger and may intensify PMS symptoms.

Pushing Yourself to Fast Increases Stress Hormones

When you hold off hunger too long, your body takes it as a “crisis” and releases a lot of cortisol (a stress hormone).

Too much cortisol disrupts the rhythm of female hormones and tends to make irritability and insomnia worse.

For your body, it’s like keeping your foot on the gas while the engine is just spinning its wheels.

If you turn fasting into a “test of endurance,” far from balancing your hormones, it could end up disrupting them.

What matters is changing the length of your fast to match your menstrual cycle and having the courage to take a break during the tough times.

Who Should Talk to a Doctor Before Fasting

If any of the following apply to you, please consult a doctor, such as a gynecologist, before you start fasting.

Also, if your PMS symptoms are severe enough to interfere with daily life, or if you’re feeling very low, don’t keep fasting on your own judgment; see a medical professional.

I explain in detail how women in particular should think about fasting time in my article on 16-hour fasting for women as well.

Signs You Should Stop Fasting for a While

If you notice changes like the following while you’re fasting, stop for now and see how things go.

Changes in your period in particular may be your body’s signal that “there’s not enough energy.”

Don’t force yourself to continue; prioritize your body’s recovery by going back to three meals a day.

Losing weight too quickly can also easily lead to irregular periods, so be careful.

Don’t push too hard with fasting as a dieting tool; take it up as a habit for getting your body in good shape.

A Concrete Fasting × Diet Plan That Works for PMS

Sample Daily Meal Schedule (Follicular to Ovulatory Phase)

During the follicular to ovulatory phase, when you feel good, I recommend a schedule based on 16-hour fasting.

For the first meal after your fast, eat protein and vegetables first to prevent blood sugar spikes.

If you’re not sure what to eat, my article on the first meal after a 16-hour fast can also help.

Sample Daily Meal Schedule (Luteal Phase)

During the luteal phase, when you tend to get hungry, have breakfast earlier and shorten your fasting time.

Going back to three meals a day makes your blood sugar waves smaller, which can make it easier to keep irritability and sugar cravings in check.

If you still get hungry, it’s fine to nibble on a few nuts or a boiled egg.

With either schedule, finishing dinner at least 3 hours before bed helps you maintain good sleep quality, too.

What matters isn’t sticking strictly to the times, but adjusting little by little to how you feel that day.

Foods and Drinks That Make PMS Worse

Before your period, try to limit foods and drinks like the following as much as possible.

You don’t need to cut them out completely; approaching it with the mindset of “just eating less of them in the two weeks before my period” makes it easier to keep going.

Tips for Choosing Food When Eating Out or at a Convenience Store

Even on busy days when cooking for yourself is hard, you can still manage PMS depending on what you choose.

At a convenience store, I recommend combining things like ready-to-eat chicken breast, boiled eggs, canned mackerel, natto (fermented soybeans), yogurt, and pre-cut vegetables.

When eating out, choosing a grilled fish set meal or a menu item that comes with a hearty miso soup lets you get protein and vegetables at the same time.

Sweet drinks spike your blood sugar quickly, so choose tea, water, or sparkling water instead.

Rather than aiming for “the perfect meal,” what matters is stacking up slightly better choices each time.

Frequently Asked Questions About PMS, Period Pain, and Fasting

Start Hormone-Care Habits That Ease PMS Today

Here’s a summary of the key points for easing PMS and period pain.

You don’t have to do everything at once.

Try starting with just “cutting back on sugar before your period” and “eating oily fish three or more times a week.”

If you keep it up for one cycle, you’ll notice your body feels different before your next period.

Jot Down Your Symptoms Along with Your Period Dates

To help with that, I recommend jotting down simple notes on symptoms like “irritability,” “bloating,” and “headaches” along with your period dates.

With a record, you’ll start to see which discomforts tend to show up at which times, and what changes made things easier.

It’ll also give you something to go on when explaining your symptoms accurately to a doctor.

When fasting, diet, and sleep all come together, your hormone balance will gradually become easier to keep in check.

Don’t Blame Yourself Even If Some Months Don’t Go Well

Even if some months don’t go well, there’s absolutely no need to blame yourself.

Your hormonal state also changes with the seasons, how busy work is, and stress, so it’s natural for things not to go the same way every month.

Focus on what you were able to do, such as “this month I managed to cut back a little on sweets during my luteal phase,” and find a pace that suits you.

If you want to learn the basics of fasting itself, start by reading my complete guide to intermittent fasting.

Just making that tough time each month a little easier can make a big difference in how you feel for a third of the month.

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