Female Menstruation + The Fasting Cycle

Sarah L. Plumer cycle fasting female menstruation mentrual

An overview of The Fasting Cycle  

Resource: The Science (and Art) of Fasting for Women Dr. Mindy Pelz 

Breaking down the menstrual cycle into three phases: the Power Phase, the Manifestation Phase, and the Nurture Phase, all named for the hormones influencing moods in each phase. 

These names are designed to help you remember what the focus of each phase is. For example, during the power phase, the focus can be to lean in to longer fasts to accelerate healing, whereas during the nurture phase, slow down with fasting efforts and nurture yourself more with healthy foods.  

Although the Fasting Cycle is built around a 30-day period, every woman has a different-length cycle. If you’re cycle is 28 days, then you will use this fasting system up to the 28th day. Once their period starts, move to day one again.  

If you have a 32-day cycle, keep following the guidelines of the last phase—the nurture phase—until the period starts, then start the cycle anew.  

While there are food and fasting suggestions associated with each phase of the cycle, remember that there is no one-size-fits-all approach. Experiment to see what works best for you. 


Quick overview of the two types of diets Dr. Mindy Peltz recommends during the month: ketobiotic and hormone feasting. 

Eating Ketobiotic:  

The ketobiotic diet is essentially an altered version of the ketogenic diet, which is ultra-low-carb.  You eat protein, a variety of vegetables and fruits, and load up on good fat.  

The rules for ketobiotic eating are as follows:  

  • Consume no more than 50 grams of net carbohydrates per day.  
  • Focus on natural carbohydrates such as vegetables and greens.  
  • Consume no more than 75 grams of clean protein per day.  
  • Greater than 60 percent of your food should come from good fat.  

The benefits of ketobiotic eating are plenty. First, if you are looking to lose weight, the ketobiotic diet keeps glucose low, letting you switch into your fat-burning energy system much quicker. This also supports optimal estrogen production. Ketobiotic also takes into account a woman’s need for more vegetables. Both your liver and gut thrive on vegetables. These two organs are essential for detoxification of harmful estrogens, so you want to make sure you are supporting them nutritionally.  

Hormone feasting: 

One of the challenges that many women faced when the ketogenic diet became popular is that they stopped eating foods that supported progesterone production. Hormone feasting foods bring these key nutrients back into your diet, boosting progesterone to elevate moods, enhance mental cognition, and improve sleep.  

Hormone feasting foods are higher in carbohydrates. This purposely provides you with more nutritional support to produce progesterone. Hormone feasting days are going to increase your blood glucose levels and most likely will kick you out of ketosis. This is intentional. This is important for progesterone production. Hormone feasting also allows you to eat more fruits, including berries, apples, citrus, and tropical fruits, giving your gut microbes new fuel that they do not get on your ketobiotic days. 

The rules for hormone feasting days are as follows:  

  • Consume no more than 150 grams of net carbs per day.  
  • Focus on nature’s carbohydrates such as root vegetables and fruits.  
  • Consume no more than 50 grams of protein per day.  
  • Consume healthy fats as desired.  

Now let’s take a closer look at each phase of the fasting cycle  

The Power Phases (Days 1 to 10 / Days 16 to 19)  

  • Suggested fasting lengths: 13–72 hours  
  • Optional food style: ketobiotic  
  • Hormone focus: insulin, estrogen  
  • Healing focus: autophagy and ketosis  

There are times in a woman’s cycle when aggressive fasting (longer than 17 hours) is welcomed and times when it is not.   

The power phases are those when you can maximize all the healing fasting can muster up, largely because this is the time when sex hormones are at their lowest levels. During your menstrual cycle there are two such low points: one is when bleeding begins and the second is right after ovulation.   

It is often during these days that a woman feels more emotionally stable, has more energy, and is less hungry, making it a great time to fast longer. 

In the first power phase (days 1–10), the body is focused on producing estrogen in order to signal to the ovaries to release an egg. Without estrogen, ovulation cannot occur. At the beginning of this phase, a woman’s body will slowly make estrogen, and as they get closer to day 10 of their cycle, their body makes a larger amount of estrogen. If they are on a high-carbohydrate diet eating six meals a day, they may be inadvertently keeping their insulin too high for estrogen’s liking. Excessive insulin not only creates a deficiency in estrogen production, but long term it can lead to a hyperproduction of testosterone. This is your classic PCOS scenario.   

The reverse happens for menopausal women. With estrogen’s natural decline through the menopause years, insulin resistance becomes more prevalent. It’s a seesaw. When insulin goes up, estrogen goes down, and vice versa.  

The second power phase (days 16–19) has another large dip in hormonal production. At this point in the cycle, a woman is coming off the hormonal surges that happen in the manifestation phase. They might feel a downward shift in their libido and less mental clarity, motivation, and energy. Because their hormone levels are at a lower point, this small four-day window is another great opportunity to go into some of the fasts that are longer than 17 hours to stimulate autophagy, repair the gut, burn more fat, improve dopamine pathways, or reset the immune system.  

The two healing processes you’ll to trigger here are autophagy and ketosis. While the shorter fasts (less than 17 hours) improve fat-burning capabilities, longer fasts are where you’ll see lasting repair of their cells happen. Certain areas of the body are more responsive to autophagy than others. The neurons that make up the hormonal control centers of the brain and the outer thecal cells of the ovaries repair incredibly well with autophagy. This is great news! Healthy and balanced hormonal production requires the brain and ovaries to be healthy. Years of high insulin and repetitive toxic exposure can cause these two body parts to become sluggish, putting hormones on a wild ride.  

Much like your sink can get backed up if it’s clogged with waste, toxins and high insulin clog the cells in the brain and on the ovaries, challenging hormonal production as a result. Periodically stimulating autophagy will quickly repair this system. Just make sure you do it during the power phases.  

If autophagy cleans the cells, the state of ketosis provides ketone fuel to power your cells up. Ketones are like rocket fuel for the mitochondria. Much like you need to charge a cell phone to keep it running, the mitochondria need a periodic ketone charge to keep them performing at their best. Autophagy and ketosis during the power phases provide a wicked healing combination for the organs that manage hormones. This makes it a great time to go into longer fasts to ensure that these organs are juiced up and ready for the next phase of hormone production.  

As far as the best food choices for your power phases, it’s best to keep glucose and insulin low. This makes the ketobiotic way of eating ideal at this time. Lowering the intake of carbohydrates while raising the intake of good fats and keeping protein in moderation is the perfect style of eating to pair with fasts during the power phases.   

The Manifestation Phase (Days 11 to 15) 

  • Suggested fasting length: <15 hours  
  • Optional eating style: hormone feasting foods  
  • Hormone focus: estrogen, testosterone  
  • Healing focus: supporting a healthy gut and liver  

In the manifestation phase, estrogen and testosterone peak and there’s also a mild surge of progesterone. All of these hormones line up in perfect synergy to help a woman feel her best. During this short five-day period, not only is a woman ready to make a baby, but the estrogen spike will spark creativity, beautify her hair and skin, and make her into a great conversationalist. She’ll also be an incredible multitasker when estrogen is high.   

But the hormonal bliss during this phase doesn’t end with a huge surge in estrogen. Women also get large amounts of testosterone at this time, which fires up the libido and provides a boost of motivation. This phase is the time to tackle big projects or difficult conversations.   

Finally, during this phase, women also get a small surge of progesterone, which gives them peace and calm.   

In the manifestation phase, you’ll want to turn your healing focus from helping you produce hormones to metabolize them. Metabolizing a hormone means two things: breaking that hormone down into a usable form so it will be more readily used by the cells, and preparing that hormone for excretion. The two organs that help metabolize hormones are the liver and gut. When these two organs are working at their best, a woman’s hormonal superpowers will peak during this time.  

One hormone that is incredibly important to detoxify is estrogen. When estrogen is not broken down and excreted from your body, it stays stuck in the tissues. Unmetabolized estrogen leads to many hormonal cancers, including breast cancer, and contributes to a whole host of premenstrual symptoms such as breast tenderness, night sweats, moodiness, and even weight gain. Because of this you’ll want to use the manifestation phase to support the breakdown and excretion of estrogen. 

The best way to do this is to shift focus from using longer fasts as a healing tool to leaning in to foods that nourish the liver and gut. Hormone feasting foods will improve bile production for the breakdown of fats, improve digestion by stimulating the proper production of stomach acid and pancreatic enzymes, and support the body’s absorption of key vitamins like B12 and iron.  

When it comes to fasting during this phase, it’s important to keep fasts under 15 hours. There is reasons why women need to fast differently! 

One reason is because hormone surges can release toxins that have been stored in the tissues. If your in a fasting state longer than 17 hours triggering autophagy, you may experience a detox reaction, like nausea, vomiting, brain fog, lethargy, anxiety, or muscle aches. This can make for a really uncomfortable manifestation period. It’s a time when you should be thriving, but can feel horrible if you don’t shorten the fasts and lean in to hormone feasting foods.  

Now what about testosterone? It is in the manifestation phase that women are supposed to get their largest testosterone surge. Testosterone is a wonderful hormone for women. It gives you motivation and drive, plus it fires up the libido. If you aren’t feeling these traits at this time, you could be low in testosterone. Food and fasting is not your best tool for improving testosterone production. Removing toxins and major stressors from your life are the most impactful steps you can take to balance testosterone levels. Phthalates are highly destructive to testosterone production; these toxins act like a synthetic version of testosterone, which enables them to enter the cells. Much like a synthetic version of estrogen is not usable to your cells, synthetic testosterone is also useless. Unfortunately, phthalates are most commonly found in plastics, and personal care products with strong fragrances like those found in commercial perfumes, shampoos, and lotions. Although avoiding phthalates is a smart move for overall hormonal health, it will impact testosterone levels the most. If you have signs of low testosterone, avoid plastics and find natural sources for beauty products and fragrances.  See my resource here for toxins. 

Stress can also come into play during this phase by suppressing the production of progesterone and testosterone, both of which require ample amounts of the steroid DHEA. Cortisol also needs DHEA in order to be produced. In a stressed state, the body will prioritize cortisol production over progesterone and testosterone. This can deplete DHEA stores and leave you with low levels of these two sex hormones. In the manifestation phase, this might feel like loss of libido and motivation, and high states of anxiety—never a great combination. You can easily have your DHEA levels checked with a hormone test so you know for certain whether their stress levels are impacting these necessary hormones.  I know a great naturopath who performs such tests. 

The Nurture Phase (Day 20 to Bleed)  

  • Suggested fasting length: no fasting  
  • Optional eating style: hormone feasting foods  
  • Hormone focus: cortisol, progesterone  

This is the phase of a woman’s cycle when they get to focus on themselves. Women so often give to others, leaving their own needs to be met last. But believe it or not, this has a hormonal consequence. Rushing around, constantly putting others’ needs ahead of their own, and stressing their bodies with lack of sleep destroys one of the most important hormones women have: progesterone.  

Progesterone calms the body and makes everything feel okay. When women don’t honor progesterone during this phase, they can feel like the world around them is spinning out of control. Hence the name of this phase: nurture.  

During this phase, figure out ways to nurture the body and watch progesterone shine.  

Here are three powerful suggestions:  

  • Skip fasting: The reason for this is that much like exercise, fasting can create small spikes in cortisol. Any increase in cortisol threatens the production of progesterone.   
  • Ease workouts: Cortisol is raised during excessive exercise. If you push your body to extreme physical limits the week before your period, it can lead to depleted progesterone stores, so shift workouts from higher-intensity activities to more nurturing activities like yoga, hiking, or long walks.  
  • Eat more carbs: The best food options during this nurture phase are back to hormone feasting foods. You can continue eating the foods you ate for liver and gut health during your manifestation phase, plus add in more starchy foods like potatoes, beans, and squashes (comfort food!). Women’s bodies are so brilliantly designed that they are more insulin resistant during the nurture phase—for a good hormonal reason. The body needs more glucose to make progesterone. Trying to get into ketosis during this time will be not only challenging but also destructive to progesterone.   

The nurture phase is hard for many women—as it’s a big mindset shift. And it comes with a lot of cravings, shame, and self-blame. Reminder that it’s absolutely normal for to crave more carbohydrates during this week. In fact, it’s by design. It’s a signal that you need to bring glucose back up. As glucose rises, progesterone will elevate, giving you a feeling of calm and preparing the uterine wall to shed. Once progesterone hits its peak, the period will start, and the fasting cycle starts all over again with your first power phase.  

Beware that raising glucose during this time isn’t an excuse to dive into a tub of ice cream or box of pizza. Be strategic about the carbohydrates youneat during this phase. 


Other areas of your life that create cellular inflammation or mess with hormones: 

Look at all areas of your life and minimizing exposure to things that create cellular inflammation or mess with hormones. 

Food: there are three categories of food to avoid. 

  • The first is the bad oils that cause cellular information and increase insulin resistance. In order to best avoid these oils, you will need to read ingredient labels. If you have these in your house, recommend throwing them out and replacing them with healthier options like olive, avocado, and MCT oil. 
  • The harmful oils to avoid are: 
  • Partially hydrogenated oils 
  • Corn oil 
  • Cottonseed oil 
  • Canola oil 
  • Vegetable oil 
  • Soybean oil 
  • Safflower oil 
  • Sunflower oil 


  • The second group of foods to avoid is refined sugars and flours. These foods are higher on the glycemic index and will put them on an up-and-down blood sugar roller coaster that can make fasting harder. 
  • Foods high in refined flours and sugars include: 
  • Breads 
  • Pastas 
  • Crackers 
  • Desserts 


Cleaning Up Your Diet 

The third group is foods filled with toxic chemicals. Many of these chemicals increase insulin resistance. Because of their insulin resistance capabilities, these chemicals are often referred to as obesogens. Commonly found obesogens are high-fructose corn syrup, monosodium glutamate, and sugar substitutes like NutraSweet. NutraSweet, for example, can spike both glucose and insulin, and can stimulate the hunger centers in the brain. This is not the optimal environment you are looking for to thrive with your fasting lifestyle. 

Here are some common synthetic ingredients to avoid: 

  • Artificial colours and flavourings 
  • Red or blue dyes 
  • Saccharin 
  • NutraSweet 
  • Splenda 
  • High-fructose corn syrup 
  • Monosodium Glutamate (MSG) 

The other toxins you’ll want to look out for as you’re cleaning up your diet are those found around the house. Things like household cleaners, shampoo, makeup, even the pans you cook with can be filled with toxins. 

Here are some common household items to look at cleaning up: 

  • Cleaning Supplies: Most commercial household cleaners contain neurotoxins, carcinogens, hormone disruptors, and other ingredients to avoid. If you download an app called Think Dirty, it can scan all the cleaners in your house and at the store. Think Dirty assigns a number to each product. We’re looking for a 3 or lower. 
  • Unfiltered Water: Tap water is full of fluoride, chlorine, medications, hormones, antibiotics, and psychotropic drugs. The quantity of hormone disruptors in tap water is so severe that it’s actually transforming fish from female to male. To clean this up, look to getting a high quality filter. 


  • Cookware/ Plates: Both Teflon nonstick and aluminum pans are toxic cookware choices. Aluminum is a toxic metal and it leaches into food when you cook with it over high heat, especially in the presence of acidic ingredients. Teflon, meanwhile, flakes off into food over time and contains carcinogens and hormone disruptors. 


  • If you use either Teflon or aluminum cookware, suggest yourswitch to a nontoxic alternative like stainless steel or cast iron. 


  • Plastics: Plastics contain BPA, phthalates, and parabens, compounds that mimic sex hormones. Regular plastic exposure can cause issues with fertility and weight gain and also increase your cancer risk. Suggest your avoid plastics whenever possible, especially in the kitchen, and be sure to never heat foods in plastic containers. 


  • Beauty Products: Beauty products are a particularly bad source of toxins. Research has found that many lipsticks contain lead and other heavy metals. Most foundation and eyeliner contain BPA, which absorbs continuously into your skin throughout the day. Antiperspirant deodorants contain aluminum and may contribute to early-onset dementia. And this is just the tip of the iceberg: there are more than 500 toxic chemicals in common personal care products. Again, we suggest using the app Think Dirty to scan all make-up and beauty products (shampoos, conditioners, soaps, and so on). Again, the product should score a 3 or lower.
  • Plōōm | self-care essentials include skincare without the harmful toxins, made from plants, blooms and botanicals, communing with nature to nurture your divine self.  

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