The Truth About Intermittent Fasting
and Your Menstrual Cycle

This post is all about intermittent fasting and menstrual cycle.

With the increased popularity of intermittent fasting for weight loss, so many of us are jumping on the bandwagon to see if it is the miracle cure to shedding that stubborn weight.

However, as women, we HAVE to ensure we are properly educating ourselves on intermittent fasting and menstrual cycles before we jump in.

Without proper education about intermittent fasting and your menstrual cycle, fasting can have lasting effects on your physical and mental health.

Unfortunately, fasting is not a one size fits all solution. And for us women, it is a TOTALLY different ballgame.

Let’s talk about the truth behind intermittent fasting and your menstrual cycle, the RIGHT way to do it and resources to aid in your journey to a healthier you!

Fasting as a Man vs Woman

Unlike men, who have a set 24 hour cycle and only one key hormone (testosterone), we are much more complex.

With our cycle averaging 28 days, 4 phases and 3 key hormones, we have to do things a little differently. Because of the constant changes and fluctuations throughout our cycle, we cannot expect fasting to look the same for both men and women- we are two totally different beings!

There are SO MANY WOMEN who are under-educated about their own menstrual cycles and hormones.

I know, because I was one of them. Until 29 years old, I was totally and completely aloof that not understanding my cycle while fasting was worsening my hormone imbalance, under nourishing my body and completely draining my adrenals.

While many people advise women to steer clear of intermittent fasting altogether because of this, I, and many other successful fasters, disagree.

If our eating, exercise and fasting schedules are fluid and fluctuate based on our hormones and menstrual cycle, we can actually flourish and feel better than ever. That part, I can promise you!

Benefits of Intermittent Fasting

1.) Weight loss

The one thing people always assume when you tell them you are intermittent fasting is that you are trying to lose weight. While this is a serious benefit, this is FAR from the most beneficial.

During intermittent fasting, your body switches over from “carb burning mode” to “fat burning mode” where it receives energy not from your food, but from your body fat. When doing this, people experience weight loss everywhere, including tapping into deeply stored fat.

In addition, when you intermittent fast, you decrease you “eating window” (or the period of time during the day you are actually eating and digesting your food). This naturally results in less calories eaten.

That is why it is so important to make sure you are eating nutrient packed foods during your eating window to compensate for the hours you were fasting.

2.) Increased Insulin Sensitivity

Intermittent fasting also improves your body’s ability to process sugar. Your insulin sensitivity greatly increases when fasting which, in turn, helps manage blood sugar.

3.) Increased Metabolic Health

Fasting can also support your metabolic health. One HUGE benefit of fasting is something called “autophagy” (coming from a Greek word meaning “self- eating”). This is a process that involves recycling and discarding old, damaged cellular components and proteins to clear cellular waste and make room for new, fresh cells.

There have been many studies that show this process is linked to increased lifespan, cancer cell destruction and reducing the risk of age related diseases.

4.) Hormone Balance

When intermittent fasting WITH your cycle, women experience a balance in hormones that help with fertility, regular periods, hormone diseases and even libido.

5.) Convenience

Decreasing the amount of food you eat can be a convenience benefit in itself. This means, less food to buy, less time planning meals, less time tracking calories, less time packing lunches, etc.

Incorporating fasting into my lifestyle with three kids has made my life 10x easier.

You may also like: What Happens to Your Body When You Fast?

The Importance of Fasting with Your Menstrual Cycle

About a year into my fasting journey, I remember listening to an intermittent fasting podcast about hormones. They talked about how important it was to eat and fast differently at different times of your cycle. Then listed all of LASTING side effects that could happen to your body if you did not.

I thought, “There’s no way all of that will happen to me”.

TAKE THIS AS YOUR SIGN THAT IT CAN AND WILL HAPPEN TO YOU.

About two years into fasting every single day AGAINST my cycle, I started developing all of the symptoms she had mentioned. Because I had felt so good for so long fasting the way I was, it took several months after the onset of my symptoms to actually figure out what I had been doing to my body and hormones.

Those symptoms can included:

• hair loss
• irregular, or even absent, periods
• infertility
• insomnia
• depression/anxiety
• weight gain
• poor metabolism
• brittle nails
• low libido
• brain fog
• short temper
• hot flashes, and more..

I have reversed many of the items on my symptom list. However months later, I still suffer from thin hair, nights of insomnia and a damaged metabolism.

Stages of the Menstrual Cycle

Going through nursing school, I probably had more knowledge about these four phases than the average person outside of the medical field. However, up until I did extensive research, read books and listened to podcasts, I still only knew the VERY MINIMAL basics.

Now that I have educated myself on this information, I have realized how little women actually know about their own bodies.

First, lets start off with the basics and go over the 4 different stages of your 28 day menstrual cycle.

(Keep in mind that age, stress level, hormonal imbalance and medical conditions can make the days of this cycle vary for everyone.)

Menstrual Phase 

(Days 1-5):

The menstrual phase when your body is shedding the lining of your uterus when no pregnancy occurred, and to prepare for the possibility of another pregnancy. During this time, you are bleeding. It begins the moment you have a real flow of red blood (I do not count days of spotting).

Follicular Phase 

(Days 6-13):

The low level of hormones during menstruation signals FSH (follicle stimulating hormone) to be released. This hormone is responsible for releasing “follicles” (or the sacs holding the immature eggs).

One of the follicles that is released becomes the dominant follicle and continues to grow.

As this follicle grows, it stimulates estrogen production. Estrogen’s main responsibility is to thicken the lining of the uterus again in preparation for carrying and protecting a baby.

Ovulation 

(Day 14):

This phase is when the fully grown (or mature) follicle releases the egg that is inside.

During this time, you are fertile and able to get pregnant.

Luteal Phase 

(Days 15- 28 or until menstruation begins again):

In this phase, the now empty follicle secretes progesterone and estrogen to maintain the thick uterine lining made in the “follicular phase”. This is to prepare for a possibility of pregnancy.

If no pregnancy occurs, the empty follicle breaks down and hormone levels decrease.

This stimulates the lining of the uterus to shed and phase 1, or the menstrual phase, begins again.

Now that you have an understanding of exactly what our body is doing during each phase of our cycle, lets dive deeper into hormones and what our bodies need to keep those hormones in check and reaching their fullest potential!

How to Fast With Your Cycle

There are 3 main hormones at play during your cycle. Those hormones are estrogen, progesterone and testosterone.

1.) Progesterone

This hormone is high:

• Around the “Ovulation Phase”
• The end of the “Luteal Phase”

Think of this hormone as your “rest and digest” hormone. This hormone does not like fasting of any kind. It wants you to SLOW DOWN and take time for yourself.

Eat rich, nutrient dense foods, but be careful with carbs as your insulin sensitivity is much lower during this time.

Be with your family, friends and people that you love.

Get a massage, take walks outside and limit your stress to the best of your ability.

***If you do try to fast during this stage, you will increase your stress hormone, cortisol. These hormones DO NOT mix and will leave you feeling hungry, dizzy and fatigued.

2.) Estrogen

This hormone is highest during your “Menstrual Phase” and “Follicular Phase”.

I look at estrogen as the strong, independent bad a** bi*** hormone. She thrives on you pushing to your maximum potential.

Even without food as fuel, she can also keep you going strong if you choose to intermittent fast or extended fast.

I feel best slowly easing into intermittent fasting during this phase as to not push too hard, too quickly. I begin fasting on Day 1 for about 16 hours. By Day 3 (or the middle of my period), I am feeling happy, motivated and ready for a more intense, longer fast.

During this phase, HIIT (high intensity interval training), heavy weight lifting, long runs and anything else that pushes your stamina is encouraged.

Insulin sensitivity is also low during this time, which means you have more cushion to eat carbs during your eating window to get through those hard workouts.

Iron rich foods are also beneficial during your period.

3.) Testosterone

This hormone is highest just before and right around the “Ovulation Phase”.

Although testosterone is the primary male hormone, women also have this hormone. It plays a pretty crucial role in our menstrual cycle, libido, mood and energy.

One of testosterone’s main responsibilities is aiding in the development of the follicles. It also helps with the maturation of the eggs preparing to be released for ovulation.

Testosterone also thrives with fasting.

RECAP

I know that is a LOT of information.

All of this can get super confusing, so let me break it down a little bit more.

Days 1-5:

Estrogen is being built. Ease into your fast slowly. By day 3, feel free to fast any way you like.

Days 5-13:

Estrogen is high. Use this time to intermittent fast at any length and even try extended fasting.

Days 13-21:

Estrogen and testosterone is high during this time. Because you are releasing an egg during, it is recommended to fast minimally. I have found success with no more than 16 hours.

Days 21-28:

Progesterone takes over and you SHOULD NOT BE FASTING!

Fasting Safety

It is SUPER important to note that if at any time during ANY of these phases you feel physically hungry (lightheaded, dizzy, nauseous, etc), you NEED TO EAT.

It is advised by medical professionals to opt out of ANY fasting if:

• You are pregnant or breastfeeding
• Suffer from amenorrhea (no period)
• Are under 18 years of age
• If you have an eating disorder

While intermittent fasting can be an amazing tool for an overall healthy lifestyle, ensuring you are knowledgeable on how to intermittent fast properly with your menstrual cycle is CRUCIAL to avoiding negative consequences!

Please let me know in the comment section how fasting for your cycle has benefited your body!

*DISCLAIMER*

All of the information in this post is based on my true and original experiences and extensive research from multiple sources.

I am not a medical doctor and none of the information in this post constitutes for medical advice in any way.

All diet and/or lifestyle decisions you make based on the information in this post should be discussed and approved by your doctor beforehand.

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