Medically Reviewed by Dr. Bryan Seigel D.C., P.L.C. – Written by Emily Ziedman
The buzz around intermittent fasting is rapidly gaining momentum as more and more people have begun to skip meals in the name of health. While the research continues to back up the personal claims you may be hearing from friends, family, and acquaintances, it’s vital to understand that intermittent fasting is not a one-size-fits-all program.
This is especially true for women and intermittent fasting. For females, intermittent fasting could be the key to health-promotion, or it could be seriously detrimental to health and wellbeing. In this article, we’ll discuss what intermittent fasting is, why it’s different for women and men, and how to choose the right fasting protocol for your biological needs.
What Is Intermittent Fasting?
Intermittent fasting is an umbrella term that’s used for a variety of eating schedules, which include extended periods of going without food. Research continues to unveil the benefits of giving your body a break from food, which is why this eating style has become so popular in the last few years.
Put simply, when you follow an intermittent fasting protocol, you’re intentionally choosing windows of time to avoid food and then strategically planning windows of time that you’ll commence eating.
There are several different types of intermittent fasting schedules to choose from. The key, however, is to know which type works best for you and your body. As the popularity of intermittent fasting continues to grow, one big mistake that many people make is to choose a fasting regimen that worked for someone else without taking into account their personal biological needs.
Although there is still much to learn about fasting, one understood fact that’s often overlooked is that fasting impacts women differently than it does men. Why? Because for important biological reasons, a woman’s hormonal system is quite different from a man’s.
Women and Intermittent Fasting: Why Is It Different?
If you look at the biology of a man and a woman, there are many similarities. In fact, it would be fair to say that men and women are much more alike than they are unalike. That is unless you’re looking at the hormonal system. When it comes to women and intermittent fasting, there are some significant hormonal shifts that can occur.
The primary reason for this is simple: women’s bodies are tailor-made to reproduce, while men’s are not. The reproductive cycle that women go through every month is incredibly energy-intensive, and the constant fluctuation in hormones throughout the cycle creates a more dynamic hormonal environment.
So how does this impact a woman’s fasting routine?
If you take an ancestral perspective, with the understanding that reproduction is an energy-intensive process, it makes sense that when food is scarce, reproduction takes the back-burner. If there isn’t enough energy coming into a woman’s body, it sends a signal “we are in the midst of a famine, this is not a time to have a child, this is a time to focus on survival[*].”
This is why many women that partake in excessive calorie restriction or fasting end up with amenorrhea (cessation of menstrual bleeding). It’s your body’s incredibly intelligent way of protecting you and a potential fetus from dying from lack of nutrition. It’s an act of self-preservation.
Of course, logically, you may look around and say, “there’s an abundance of food here; I’m not going to die of starvation if I skip a few meals.” But your body doesn’t run off logic; it runs off the signals it gets from your environment.
Other common side effects that women experience with excessive fasting include extremely low energy and brain fog. Again, this is just your body’s way of conserving energy to protect you from the impact of famine.
On the one hand, we can thank your body for being so tuned-in to your environment that it knows when to go into energy-preservation mode. On the other hand, however, the process of halting a woman’s menstrual cycle can create hormonal havoc. In fact, research in animals shows that fasting in excess can lead to biological changes like masculinization, lowered sex hormones, a heightened stress response, and reproductive shutdown in females[*][*].
Furthermore, when you restrict food, it activates a stress response in your body. While in small doses, this can actually be beneficial, when overdone, it can create a harmful imbalance in stress hormones like cortisol, which further push your sex hormones out of whack[*].
Does this mean that women should avoid intermittent fasting altogether? Not necessarily. It comes down to the type of fast you follow and the ability to listen to your body’s signals.
In fact, intermittent fasting can have some significant benefits for women.
Intermittent Fasting Benefits For Women
The intermittent fasting benefits for women are similar to those for men, as long as you don’t overdo it. When you intentionally restrict your caloric intake, your body responds in several different ways, enhancing its ability to turnover cells and upregulating several pathways, which can lead to disease prevention and optimal body mass.
Below are a handful of the most well-researched intermittent fasting benefits for women.
One of the most well-known benefits of fasting is something called autophagy. If you haven’t heard of it before, autophagy is the process of cellular cleanup in your body. It’s basically your body’s way of cleaning out old cells and debris and making room for new, more optimally functioning cells.
When you fast, it upregulates the process of autophagy in your body, enhancing your ability to clear out the old and make way for the new. Studies show that when autophagy is working optimally, one of the primary results is an extension of the lifespan.
In fact, there appear to several different mechanisms by which autophagy directly promotes longevity due to its impact on cell turnover and gene expression[*].
What’s more, it appears that autophagy may have a direct impact on brain function, as diminished autophagy can lead to neurodegeneration — an underlying issue in neurodegenerative diseases like Alzheimer’s and dementia[*][*].
Fat Loss With Muscle Retention
When trying to lose weight, one of the most common downsides is that as your body burns off some fat, muscle tends to go along with it. Since muscle is the most biologically active tissue in your body, it can negatively impact your metabolism when you lose significant amounts of it[*].
The result? You lose some fat, but you also end up with a lower metabolic rate, which can make it easier to pack the pounds back on.
Research shows that intermittent fasting is an effective strategy for weight loss. Even in obese populations, it appears that intentionally choosing windows of fasting can assist in stubborn fat loss[*][*].
While this likely comes as no surprise, what makes intermittent fasting so unique is that biologically, your body also appears to preserve your muscle mass when you fast. This means that fat stores become depleted, but muscle mass stays intact. In other words, you get to burn fat without burning out your metabolism. This makes it much easier to keep the weight off and avoid a yo-yo dieting trap[*].
Inflammation is said to be at the root of almost all chronic diseases. Unfortunately, our modern lifestyles are like landmines for inflammatory triggers. Poor diet, overwork and stress, and environmental toxins all play a role in your body’s inflammatory processes[*].
The result is that as a society, we see increasing levels of chronic conditions like heart disease, diabetes, cancer, autoimmune disease, and neurodegenerative disorders[*].
When you fast, it can increase your body’s resistance to chronic inflammation by upregulating essential anti-inflammatory pathways while downregulating the inflammatory response[*][*].
What’s even more interesting, however, is the impact that fasting has on acute inflammation. Unlike chronic inflammation, which can lead to imbalance and disease in your body, acute inflammation is necessary for tissue repair and the maintenance of a healthy immune system.
Research shows that while fasting tempers your chronic inflammatory response, it doesn’t compromise your acute inflammatory pathways — meaning that you essentially get the best of both worlds for optimal inflammatory activity in your body[*].
May Improve Psychological Well-Being
While fasting may take a little white-knuckling at first, the motivation you experience once you get into an intermittent fasting routine may come from more than a sense of pride.
Research shows that intermittent fasting may increase the production of neurotransmitters that are responsible for a positive mood and outlook. Specifically, it appears that levels of serotonin and brain-derived neurotrophic factor (BDNF) significantly increase after periods of fasting[*].
Clinical research also shows that for those with a history of eating disorders, following an intermittent fasting protocol can result in positive shifts in body image along with a decrease in depression and binge eating behavior[*].
It should be noted, however, that these trials take place under clinical supervision, and if you have suffered from an eating disorder, it’s crucial that you work with a healthcare professional before deciding to try out intermittent fasting.
Potential Downfalls That Come With Women and Intermittent Fasting
Aside from the potential issues with hormonal balance, there are a few other downsides to be aware of when it comes to intermittent fasting for women. While these certainly won’t impact everyone, you may want to be mindful that fasting may result in the following side effects[*]:
- Bad breath
- Water retention
- Trouble sleeping
Women And Intermittent Fasting: The Best Protocols
If you’re starting an intermittent fasting protocol for the first time, it’s always best to start slow and build up — this goes for both men and women.
With that being said, for the female population, it’s twice as important to ease into fasting and give your body a chance to catch up to your new dieting protocol.
A few of the best intermittent fasting approaches for women include:
This method of fasting is one of the most popular and is also referred to as the 16/8 method or “Leangains.”
With eating windows, you first choose how many hours you want to fast, then pick an eating window around your fasting period. For example, the most popular eating window protocol is the 16/8 method, where you fast for 16 hours a day and eat all your food within an 8-hour eating window.
This could look like fasting until 11 am, eating until 7 pm, and then fasting again until 11 am the next day. During the hours of 11 am and 7 pm, you would consume all your daily calories, and after 7 pm, you begin your fast.
Eating windows is a great way to start a fasting protocol because you can play with the windows. Many women find that a 14:10 fast is perfect for them, as it allows for a wider eating window with the benefit of 14 hours of fasted time.
You can even start with a 12:12 fast to dip a toe.
The 5:2 Diet
The 5:2 diet is a fasting protocol that involves reducing your caloric intake to about 25% of your normal daily calories for two days per week and eating normally for the remaining five. This typically looks like two days per week consuming around 500 calories, with five days per week of regular caloric consumption.
The 5:2 diet offers a nice easy transition into fasting as the majority of your days will remain the same, and your two fasting days will still include some caloric intake.
Modified Alternate-Day Fasting
A traditional alternate day fasting regimen includes fasting every other day and eating normally on non-fasting days. This is an advanced method of fasting as you end up fasting for more than 24-hours several times per week.
With a modified alternate-day fast, you can still consume about 20-25% of your typical caloric intake on your fasting days (much like the 5:2 method) and then eat normally every other day.
Eat-stop-eat is another popular intermittent fasting protocol that includes one or two 24-hour fasts each week. It’s suggested for women to begin with one or two 16 or 14-hour fasts and slowly build up to 24-hour fasts.
It’s also important to make sure you don’t go over the 24-hour mark. For example, if you decide to start your fast after dinner at 7 pm Monday and then fast all day Tuesday, when you wake up on Wednesday at 7 am, you’ll have gone through a 36-hour fast.
Instead, try skipping dinner on Monday and ending your last meal by 2 pm, and then breaking your fast at 2 pm on Tuesday. This gives you a full 24-hour fast, and you still get to consume food each day.
When it comes to intermittent fasting benefits for women, less is often more. In a society where we push our limits and are always competing against ourselves to try to reach new levels of health, success, you name it, slowing down can be a tall order.
The potential downfalls of excessive fasting for women are a perfect example of how this go-go-go mentality can backfire.
Does this mean women should skip fasting altogether? Absolutely not. There are plenty of intermittent fasting benefits for women; you just need to know which protocols to follow.
If you start to feel unpleasant side effects (aside from a little lethargy and perhaps some hunger pangs when you first begin), it may be a sign that you’re pushing too hard.
Furthermore, it’s always important to run any new dieting regimen by your healthcare practitioner to be sure that it’s the right match for you. This is especially true if you are currently taking any medications, are managing an acute or chronic disease, or have a history of an eating disorder.