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The Complete Guide to Fasting for Women Part 1: Should Females Fast?

fasting for women

Fasting continues to make headlines. Every day more research is published revealing its application to everything from heart health to neurodegenerative diseases, cancer prevention, autoimmune disorders, and nearly everything in between. For these reasons and many more, we’re big fans of having a regular fasting practice.

But there’s one glaring truth that seems to fly under the radar as fasting gets more popular…

Most of the studies on fasting have been conducted on rodents or men… Which means there’s very little research on how fasting impacts women.

This is a problem. As fasting gets more mainstream, many females are starting to adopt it as a regular practice without fully understanding how it may impact them differently. Women see men thriving on daily 18-hour intermittent fasting (IF) or one meal a day (OMAD), with their shredded abs and endless energy, and think it’ll work for them, too.

And while we're not arguing that fasting can absolutely be helpful for some women, there’s no doubt that others are experiencing negative side effects from frequent fasting.

So in Part 1 of this two-part series on fasting for women, we're taking a deep dive into:

  • What the (limited) research tells us about how women respond to fasting
  • How and why fasting affects women differently than men
  • How to determine if fasting is right for you

And because we haven’t seen this topic covered in great detail before, we wanted to do it justice. Hence, our first ever two-parter! (Part 2 here.)

So buckle up, it's gonna be a doozy…


Should Women Fast?

The main question we’ll attempt to answer in this article is the obvious one: Should women fast?

The answer, unfortunately, is not so obvious. Put simply: It depends.

When you pose this question to an average health expert, you’ll get some pretty polarizing, absolute-sounding answers…

  • Either a resounding “Yes, everyone should fast!” with no qualifiers that females should consider a different approach.
  • Or, you’ll be knocked over with a booming “ABSOLUTELY NOT. WOMEN SHOULD NEVER, EVER FAST. THAT'S DIET CULTURE BS!”

However, we’re inclined to take a more balanced approach. The answer is not black and white. Fasting can work wonderfully for some women, and for others it can be a really, really bad idea.

Like most health-related topics, bio-individuality is king (or should we say, queen). This is equally true when it comes to how fasting affects different sexes.

Yes, This Article is Written by a Woman…

In case your gender equality radar is already going off, we feel the need to disclose a few things…

First, because we know you're probably wondering… the author of this article is indeed a female. Every word is written with a deep understanding and compassion for other women and the unique health issues we experience. (And now, please excuse my not-so-graceful switch to first person to make this less awkward.)

Secondly, I do in fact believe that all sexes are equal… but also equally different.

As Dr. Stacy Sims says so beautifully: “Women are not small men.”

Women are different than men in so many wonderful ways, and therefore we require different approaches to our nutrition, fitness, and yes—even how we fast.

Third, I have practiced fasting for over a decade. I've used it as a tool to improve my gut health, immune system, skin health, and as a way to manage an autoimmune disorder as naturally as possible. But I've also found out the hard way that more fasting is not always better, especially as a female.

Before getting into the details of how women should fast, let’s talk about why they should consider a different approach.


The (Few) Studies on Women and Fasting

While there are admittedly not that many human studies on fasting, there are even fewer on human women, and many of those studies are on overweight and/or post-menopausal women.

When it comes to healthy, pre-menopausal women, we don't have much scientific ground to stand on.

(This is not a trend limited to fasting, by the way. Most health-related studies are conducted on animals or men, not young women. To put it simply, we are very complicated to study in an n=1 environment. We are cyclical creatures, with hormones that fluctuate daily. To control for every variable—meaning every woman is in the same phase of her cycle at the same time, and has the same length of cycle—is quite a difficult and expensive task.)

Therefore, finding a definitive, science-backed answer to the question of whether or not women (especially young, healthy women) should fast is nearly impossible at this point in time.

However, we can certainly make some hypotheses based on the research.

Here’s a synopsis of the small amount of animal studies on fasting that involve females:

  • One study found that in response to 3-6 months of alternate day fasting (ADF), female rats became emaciated, ceased cycling, underwent endocrine masculinization, and exhibited a heightened stress response. The male rats, on the other hand, maintained a higher body weight than the females and did not change their activity levels as significantly.
  • Another study on rats showed that 3-6 months of ADF led to a reduction in ovary size and irregular reproductive cycles in female rats.
  • A study on male and female rats found that dietary restriction via intermittent fasting caused adverse effects on fertility and the suppression of reproductive capabilities in both sexes.
  • Another investigation on male and female rodents noted a negative effect on reproduction from intermittent fasting, indicated by significant changes in body weight, blood glucose, estrous cyclicity and serum estradiol, testosterone and LH.

As for human studies, a few highlights include:

  • A study on a small group of menstruating females noted that after a 72-hour fast, the women had decreased thyronine levels, increased cortisol secretion, and amplified nocturnal secretion of melatonin (resulting in a circadian phase shift of 81 minutes).
  • One final study highlights the gender discrepancy in glucose response as a result of fasting. After three weeks of ADF, the women had a slightly impaired glucose response to a meal while men showed no change in response.

OK, It's Not ALL Negative…

While most of those results seem negative, keep in mind that these are experimental studies, mostly done on animals. They don't paint a full picture, but they should make us stop and think about the gender differences with fasting.

On the contrary, it should be noted that other studies on fasting as a therapy for cancer and neurodegenerative diseases show promising results for both males AND females.

In his article on fasting and women, Mark Sisson sums up this dichotomy quite nicely:

“As it stands right now, I’d be inclined to agree that pre-menopausal (and perhaps peri-menopausal) women are more likely to have poor—or at least different—experiences with intermittent fasting (at least as a weight loss tool). That said, it appears to be a potentially gender-neutral therapeutic tool for chemotherapy, cancer, and age-related neurodegeneration patients.”

While the science is limited, from these studies we can at least start to make an argument that women have a different (sometimes more negative) response to fasting than men.

So… why is that?


Why Fasting May Affect Women Differently

The Ancestral Explanation

The idea that fasting—or any shift in calorie intake—affects women differently makes a little more sense from an evolutionary perspective. One of the primary roles of females in evolution has been to grow and nourish the next generation. Even if you’ve made the decision not to have children (which we fully respect!) this is a pretty incredible thing women can do.

Like it or not, this evolutionary role comes with some baggage. Procreation is a very ‘expensive' process.

Because of the energy and nutrients required to conceive, grow, and nurture a child, female bodies are naturally much more sensitive to external stressors.

For men, on the other hand, procreation is… ahem… not nearly as energy-demanding.

When the female body senses too much stress, whether that's from calorie restriction, infrequent meals, not enough sleep, too much exercise, or something else, reproduction is the first process that gets shut down. The last thing your body wants to do when it's stressed out is give all your precious energy to a growing baby.

Makes sense, right?

So, that's the simple explanation. If you're not satisfied with that, here's a slightly more scientific and complicated answer of why fasting affects women differently…

The Scientific Explanation

While the exact mechanism is a bit unclear, women seem to have a more severe response to calorie restriction or fasting due to negative impacts on several hormones including gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH) and estradiol—all of which are required to be in balance for proper reproductive function.

One explanation is outlined in a study titled Intermittent Fasting Dietary Restriction Regimen Negatively Influences Reproduction in Young Rats:

“These findings support the current data suggesting that increase in estradiol level in IF-DR (Intermittent Fasting-Dietary Restriction) female rats may lead to down regulation of GnRH and LH level via negative feedback. The reduced gonadotropin secretion may be due to the inhibitory effect of estrogen at the pituitary level and androgens at the hypothalamic level.”

In other words, by disrupting upstream hormone precursors and signalling molecules, fasting may down-regulate reproductive hormones in females (rats, to be fair).

When these reproductive hormones are disturbed, a whole host of well-documented issues can occur depending on that woman's sensitivity to hormonal irregularities. These include:

  • Menstrual cycle irregularities
  • Infertility or trouble getting pregnant
  • Complete loss of menstruation (amenorrhea)
  • General hormone imbalance symptoms (PMS, acne, poor mood, weight issues, low libido, etc.)

And listen, infertility isn't just a problem for women who want children. Even if you never plan to get pregnant, the health of your reproductive system is still critically important to your overall well-being as a female.

Your sex hormones are vital for strong bones, protection against cancer, mood, energy and vitality, sex drive, skin and hair health, and so much more.

These hormones are—in essence—what make you a healthy, vibrant, bad-ass woman. Babies or no babies.


How to Know If Fasting Is Right for You

So, does all of this mean women should never fast? Not necessarily…

At Kion, we believe in bio-individuality: that each person's health needs are unique. The perfect diet, fitness plan, or fasting practice simply doesn't exist because we all have different genetics, activity levels, health conditions, and more.

Whether or not it's a good idea for a specific woman to fast depends on a number of factors.

How old are you? Why are you fasting? What are your goals? How active are you? Do you have a history of hormone issues or imbalances? Are you planning for pregnancy soon?

While it's impossible to address every scenario, what we can do is provide general guidelines for women who should probably think twice about their fasting practice. These are the populations that are already on the fine line of hormonal imbalances, and caloric shifts via fasting may tip them over the edge into full-blown hormone dysfunction.

Fasting may not be ideal for women who:

  • Are athletes or very active
  • Are extremely lean (<18%)
  • Have sleep disorders or poor sleep
  • Have low reproductive hormone levels
  • Have subclinical hypothyroidism (low thyroid hormone)
  • Struggle with infertility, irregular periods, or amenorrhea (unless associated with PCOS or obesity, in which case fasting may benefit)

The following groups of women should definitely avoid regular extended fasting (no more than 12 hours), and would be better of focusing on getting in a surplus of calories and nutrients:

  • Young women and teens
  • Women planning for pregnancy
  • Pregnant or breastfeeding women
  • Females with a history of eating disorders

Additionally, if you currently practice any form of regular fasting and have experienced any of the following, you may want to consider a different approach (stay tuned for Part 2 of this series):

  • Poor sleep
  • Low libido
  • Thinning hair
  • Acne or dry skin
  • Always feeling cold
  • Irregular heartbeats
  • Slow recovery or healing
  • Negative changes to mood
  • Decreased athletic performance
  • Binge eating or strong food cravings
  • Inability to lose weight or unexplained weight gain
  • Irregular menstrual cycles or loss of period (amenorrhea)


Final Thoughts on Fasting for Women

It's true that fasting can have an incredibly positive impact on health. We're huge believers in the powers of fasting and have written about it extensively (here, here, here, here, and here). We even host a 5-day fasting challenge each year to educate more people about it!

But we're also not blind to the fact that female-specific studies (or lack thereof) are often left out of the discussion.

Yes, there's still research to do. Until then, if you choose to practice fasting as a female—especially a young woman of reproductive age—pay attention. Listen to your body.  If it's telling you something, don't ignore it for the sake of self-discipline, or ‘autophagy', or abs. You'll likely do more harm than good.

On the other hand, if you find fasting to be a beneficial practice in your life and only experience positive results, then continue on your journey! You're the one that knows your body best.

If you found this article helpful, let us know in the comments. And be sure to read Part 2!

66 thoughts on “The Complete Guide to Fasting for Women Part 1: Should Females Fast?

  1. I found this article extremely helpful as a female and found a lot of new information. As a female age 34, without any kids and plans to hopefully have them in the future, this opened my eyes to some things I am glad to now be aware of.
    I have been doing cyclical ketosis for over 3 years, and love it. After 1 year of 1-2 16/8 fast days a week, I hadn’t actively sought out the recommendations for women vs men on fasting, I just tried what so many others have been recommending.

    I found that I very much liked the benefits of IF, and the simplicity of just eliminating choices for meals in the morning. I used to spike in energy on a fast day, much like the bump of getting into ketosis which I loved. The longer into a fast the less interest in food applies for me too.
    However, after reading more has made me wary and re-evaluate.
    I have noticed a plateau in energy. Where I used to get a burst of energy after a fast, it is ready steady-lined at this point. I would be in the lean fat group with regular exersise. I have noticed less drive for the high-intensity workouts, and more focus on restorative, yoga, slow resistance training. I do often feel cold, and not much of any hormonal changes.
    Food (or no food) for thought appreciated!

  2. I went paleo in 2010, began IFing shortly thereafter. At the time, I was cycling a lot and running marathons. I regularly fasted during my workouts. My fasting cycle was around 16 hours. In 2013, my period completely stopped (I was 48), and then in 2014, I was in stage 3 hypothalamus-pituitary-adrenal dysfunction (also known as adrenal exhaustion), I was producing little T3 (active form of thyroid hormone), and all my hormones were in the toilet. Also, I believe my glucose regulating system has never been able to heal properly. I have high HbA1c (pre-diabetes) no matter how I eat. I believe the IFing while extreme exercising threw my body into metabolic chaos that I’ve never been able to recover from fully. While one doctor told me that going into menopause was normal at 48, I digress. It may be common, it’s not normal, and as you stated in the article, normal hormone levels are needed for so many aspects of health and feeling good. I am a nurse, a practitioner with Functional Diagnostic Nutrition, and I used natural means such as supplementation, essential oils, diet, and other lifestyle modalities to heal my body. I’m in pretty good health, I take no medications, but as I said, my glucose metabolism has never regulated to normal. I have gone back to a more moderate carb diet geared toward being a vegan. The keto diet does not do well for me, my blood glucose goes sky high. I supplement my protein needs with Kion Aminos. We are all different and this end all be all advice to fast and to use the Keto diet is not healthy for everyone. I wish I had known then what I know now. IFing for many women is bad juju. I hope I can be an example to keep more women on a healthy track.

    1. Thanks so much for sharing your experience, Michelle! This is really powerful and a great example for other women. You’re incredibly strong for be able to bounce back from that, and for continuing to educate yourself. Much love to you!

    2. Glad you commented here! I found that after several months of disciplined IF, I became leucine-deficient (micronutrient panel through Vibrant verified). My symptoms were noticeable in my face, skin and hair. I also had an old joint injury resurface–so many issues and only a 4-6 lb loss. None of the IF proponents one talks about this. I think it’s because people don’t get tested and may not be all that observant, or may chalk them up to other factors like “normal” aging.

  3. Yasss!! So excited to finally have some answers to the fasting for women debacle. I have been thoroughly confused on wether I should fast or not. Guidelines are immensely helpful at this point. I was just thinking today as I was listening to the podcast that I wish there was the girl only version of Ben greenfield. It gets hard to decipher what applies to me as a woman and what I should ignore.

    1. Thanks for reading Samantha! We agree, Ben should clone himself as a female! 🙂 In the meantime, here are some other experts we’d encourage you to follow for more women’s health content: Dr. Jolene Brighten, Dr. Lara Briden, Dr. Stacy Sims

      Best of luck to you!

  4. I’m 62, Post menopausal and very active physically. I lift heavy weights 3 x a week, do a HIIT based hour long class twice a week and play 2-3 hours of beach volleyball once a week. This doesn’t include my dog walks plus I work 3 12s a week as an ICU Nurse.
    I eat pretty much Paleo- I’d say close to 85-90%. My labs I do yearly and they look pretty much the same.
    Things I noticed in the past year while 16/8 fasting:
    I get cold physically toward the end of my fast.
    I can lift in the gym. I’m talking squats. Dead lifts etc. right at the end of my fast with no effect to my strength.
    I can perform HIIT and walk the dog etc while at the end of fast no I’ll effects.
    I’m become less hungry and less fixated on food the farther into the fast. Like I forget to eat.
    BUT I bonk about 3-4 games into beach volleyball and we usual shoot for 6 games.
    And the day I play, I’m very exhausted for the rest of the day.
    I’m biohacking this- I’ve decided to eat carb plus fat prior to the activity and sip whey Protein while playing next week. To see how I feel.
    I keep track of my steps via a Fitbit.
    Sleep, I track on an Oura ring.
    My diet really is clean.
    I’m on no meds -only sups (Collagen) and vitamins, minerals.
    I have no medical comorbidities.
    I’ve been intermittent fasting for 1 year 3 months or so.

    1. Thanks for sharing your personal experience with fasting, Theresa! We’ll have more information on fasting post-menopause in Part 2. Stay tuned!

  5. Very interesting article indeed, thank you for writing it. I’m on a 16:8 fasting diet for about a month now, a bit overweight that prompted the diet (140 lb to my 5’3″ height). I’m in my late thirties and trying to conceive for a year now, so I actively track my fertility signs. What I have noticed is that in the first few days of fasting, I was overeating in the eating periods as if my body was “worried” that not enough food was coming in its way so better to stack up some storage whenever food was on the sight. This normalized after a few days, now I am eating normally without any effort to restrict myself or exercise some portion control. As far a the reproductive system is concerned, my follicular phase (before ovulation) was very-very long (29 days), however, my luteal phase remained normal and I did ovulate. I suspected the change in my diet as a culprit for the delayed ovulation and this article seems to confirm it. I’ll keep continue the diet though for now to see whether it influences my next cycle, as any changes could affect the cycle. For example, my first month with my fertility acupuncturist had the same delaying effect but then in later months the acupuncture sessions actually regulated by cycle. So let’s see what happens next month.

    1. Thanks for sharing your experience here, Moa. Seems like you’re very in tune with your body and what it’s telling you. Keep us posted on your experience, and sending you healing fertility vibes! 🙂

  6. Thank you for starting to share information specific to women. Keep it coming! I would love to know more about how we can tell if fasting is contributing to longevity and overall health goals – what are the best blood / other tests or metrics to track? How often should we measure? What should we ask our functional medicine doctors to help us with? Apart from listening to our bodies and tracking sleep, mood, energy, etc, I like to know what’s working! I want my mitochondria happy and all my cells doing their best work so I can crush life until age 150. How do I know what’s going on in there??

    1. Hi Kristie, thanks for taking the time to read our article! Those are great questions. We’ve taken note of them to answer in Part 2 or another related post. So stay tuned!

      In the meantime, Ben Greenfield’s new book Boundless has a ton of great information on blood tests and other longevity metrics to track. You can also work with one of our qualified Kion Coach health practitioners at

  7. Loved the article. Need more such women centric articles, with women specific bio hacking / ancient rituals / hormone balancing protocols. Can’t wait for part 2.

  8. I am so grateful for you for bringing this to light. I practiced IF for years and completely messed up my endocrine system. I’ve been much more gentle with myself – my workouts, fasting, etc, but am still a mess. It is unfair and quite cruel that information out there is so male biased – and we are not told this upfront. I am certain this bias exists in most research studies. I have so many questions. I hope part 2 addresses some of them. Thank you again. We need more honest reporting and deciphering of information like this.

    1. Thanks so much for taking the time to read, Fatima. We appreciate you sharing your story. We’re certainly trying to cut through those biases and provide helpful, honest information. Stay tuned for Part 2, and if you have more questions don’t hesitate to post them! Best. xx

  9. I am eager to hear what part two has to say. I am 52, no period for over three years, and the menopausal symptoms seem to have ceased (no hot flashes since August). I have used time restricted eating over the past year as I’m healing my body from Candida and Thrush. It makes sense to me to use the fasting to give my gut time to heal/repair. I haven’t had negative side effects from it. Also getting really tired of some people telling me that IF is bad for ALL women, when clearly it is not. I have been told there’s no research on women and that the research there is on young men. So when I hear this, that says there’s no research on men past early 20s either! So does that make it fair game to say IF is wrong for both sexes??? I am hoping part two will have some thoughts to throw back at those who tell me my life style is wrong.

    1. Hi Colette, thanks for sharing your thoughts and experience with fasting. We definitely agree there are cases when fasting is helpful for women–not harmful. This is usually true with post-menopausal women. We’ll share more about that in Part 2!

      1. Thank you for Part 2! Just read it. Given my health concerns (Candida, Thrush, Lipedema, Fibromyalgia), I feel the time restricted eating gives my digestive system some proper down time. I have experienced my blood sugar stabilizing, no afternoon crashes, no “shakes”, no desire to binge when I’ve gone too long without eating, the hunger is just not there like it used to be. As a confessed sugar addict, the fasting and keto has cured my sugar cravings. We are all different, both men and women, that’s for sure. This is the best I’ve felt in years.

        1. Awesome, thanks for sharing Colette! Fasting does seem to help women dealing with autoimmune and gut issues, but yes, we are all different! So glad you’ve found success and are experiencing some relief and healing.

  10. 66 year old female on HRT for 8 years. IF for 16 hours daily and have been recommended to change to no more than 14 hours. % body fat 16%. Sleep always a challenge, deep sleep low and frequent waking. Have joined the 5 day water only fast both years. GOALS with fasting are: autophagy and stem cell stimulation. Looking for a good fasting formula for me for these goals. Would a shorter IF and a fasting mimicking 5 day period be preferable and still achieve my goals?

    1. Hey Diane! We’ll have a lot more information on specific protocols in Part 2, but in short, yes– if your main goals are autophagy and you’re already lean and not sleeping well, we’d suggest cutting down on the daily IF and instead doing a 3-5 day fast 1-4x/year and/or a 24 hour fast every two weeks. You’ll get more autophagy benefits with the longer fasts, and they should be safer for you being post-menopausal. Hope that helps!

  11. There are whole communities of religious people who regularly fast.
    As a Muslim woman, I fast 3 of the 4 weeks of Ramadan each year… this is more like time restricted eating (who else wants a concise list of definitions around this topic???) since it is from sunrise to sunset which changes month to month (the Muslim calendar is about 11 days shorter than the standard Gregorian calendar, thus when Rahmadahn is observed changes year to year; now it will be in May). So, depending on the time of year and your latitude on Earth, this daytime time restriction fluctuates from 8-18 hours.
    And then I regularly fast 2 days a week, 3 weeks a month through the rest of the year.

    What’s my point??? That there’s a whole cohort of women to study that no one seems interested in “finding.” That’s a lot of women that could be divided into sub-cohorts.

    And as for my experience, I am 43, still fertile though abstinent at the moment, mother of 5. I have done IF for 3-5 years now and Rahmadahn for 20. I am thin at 112 pounds and 5’4”. My home biometrics scale says my visceral fat is 3% and my biological age is 19…. I have plenty of energy, no disease chronic or otherwise, feel vital, and am generally happy (high stable mood). My general diet is healthy, lots of fruits, veggies, nuts & seeds with a mix of non-gluten options through the day. I love my fat like tahini, nut butter, & coconut milk. Overall, I feel stable and balanced. As for my hormones specifically, I have had a shortening in length between periods from the typical 28 days to 22-24 and my periods generally last 6-8 days with only 2 heavier days in there. So pretty normal!
    In short, I believe IF supports my overall health & metabolism, keeping my weight & overall fat composition low, while still supporting my immunity & vitality.

    That’s my N of 1 report 😁

    1. Couldn’t agree more on the potential of the Muslim cohort for fasting studies! There’s been some really good work done evaluating the effects of fasting on athletic performance (on men) during Ramadan, which had some really interesting conclusions about whether or not fasting affects (men’s) ability to perform at their best. I’d love to see similar studies on Muslim women.

      My N=1 report (as Judy so elegantly phrased it) is a little different to most others I’ve seen here so far:

      No children and not planning to
      180 cm tall (6 ft) and 80kg (176lbs)
      Active multisport athlete (amateur)
      Diagnosed with multiple sclerosis 2 years ago
      Fasting protocols based on studies which consider fasting effects on the immune system (e.g. the work of Valter Longo). Currently doing:
      1-2 x 24h fasts per week
      1 x 5 day fasting mimicking protocol per quarter.

      I don’t find I have any major side effects as described in Part 1 of the article, I seem to tolerate it pretty well. And my MS is stable, which is my main goal! Looking forward to reading Part 2.

    2. Hey Judy, thanks so much for sharing your personal experience with fasting! We agree that there’s so much possibility there to study women who practice fasting during Ramadan! There’s actually a few studies that have been done already if you search “fasting women Ramadan” in Pubmed. Here’s one:

      It’s awesome to hear your positive experience with fasting. Like we mentioned in the article, it can work beautifully for some women (like you) and for others it can be a negative experience (like others that have commented here). Just another great reminder that we’re all different and more research needs to be done.

      Thanks for taking the time to read and share! xx

  12. Also keen to know more about the effects on menopausal women – 54 and just starting menopause. Some slight sleep disturbances but I’d put that down more to menopause than intermittent fasting.

  13. I am 58 and have not had a period in 6 years – am really interested in what you have to say about fasting and menopause.
    I have been fasting about 3 years but have not lost weight from it. Am hypothyroid from adreanal issues apparently and am on the bioidentical form of HRT. I have always felt better and more energetic when fasting. My thinking is clearer and I can work for much longer periods, it seems to energise me. I have been an emotional eater most of my life and fasting gives me freedom from this.

    1. Such great timing of this post! I just completed my very first 4-day long water fast as a 22 year old, so I have been wondering about the effects fasting may have for my female body.

      Something I find fascinating is that all articles always state that people who have suffered form eating disorders should not try fasting. I would like to offer my experience as a woman who has suffered from a decade of various eating disorders, and has completed hospital and inpatient treatment for anorexia and bulimia. I have been out of treatment for 2 years, and have relapsed into bulimia with a horrible intensity since returning to university. I decided to go on a 4 day fast on a whim, some deep voice within said it was the right things to do.

      I was afraid that fasting would be impossible for someone like me who had a horrible relationship with food, but in fact, I must say that it has so far had profoundly positive effects. My 4 day fast revealed to me the value in life beyond food, I spent those four days working and learning and exploring my mind without the distraction of food, and I had the most beautiful time. The clarity of mind and good mood that came with ketosis left me feeling incredibly proud of myself, and happy for being able to enjoy life without being so psychologically dependent on food.

      Returning back to a normal eating regime has been a lot easier than anticipated. I feel like the fast was an experience that helped me to re-evaluate my relationship to food through personal empowerment. I also seem to have improved hunger signaling – I can feel when I am hungry, and differentiate that from emotional cravings. I also no longer feel the need to binge incessantly because I know that I can also enjoy the present moment without food.

      It has been so so so positive! I think that someone who suffers from certain forms of binge eating or bulimia can greatly benefit from a fast if done carefully and lovingly.

      Just wanted to bring this up to show that fasting need not be detrimental to folks who suffer from eating disorders!

      1. Maree, thank you so much for sharing your story. What a beautiful, inspiring experience. Grateful to you for reading and being willing to share! xx

  14. I am a menopausal woman whose last 3, five day fasts resulted in longer and longer recovery times with each subsequent fast. I was looking forward to the great feeling on day 4 that did come in earlier fasts, but, not now. The last fast took months to recover from. In my whole life I never ate three times a day. I tried Mike Mutzels Metabolic Monday challenge of fasting one day a week. It was not hard to go a day without eating. I liked it, but, I started eating more on Sunday. My internal clock knew when Monday was coming around before I knew it. It made no sense to pig out on one day and fast the following.

    Somewhere along the line, fasting was working for me and then it wasn’t. I’d love to know how to cross back in to it being beneficial.

    1. Yes, more info for menopausal women. I am 57. I dont eat early in the morning or late at night, so not eating for a 12 or 14 hr period is normal for me. My thyroid levels are “ low normal” so I consider that hypothyroid. Next blood draw will check thyroid antibodies. Some switch flipped with menopause and I gain weight so easily and have difficulty loosing it. Otherwise I feel great and have plenty of energy and don’t have any health issues. I’m writing this doing a good sweat in my infrared sauna. Thanks for any info you can provide.

  15. Hi, Dr. Beth Westie on YouTube has had a lot of experience with Women & fasting she might be a good resource for future articles, as she works only with Women…she also has stated that a lot of the studies were done on Men..I reached out to her after I was on a 52 hour fast with adverse effects..and she recommended that Women go no longer than I think 16 hours…I’ve also noticed that everything we eat drink frequency of eating has effects on our hormones…I think there needs to be a lady version of Ben:) 🙌🏽😊but he’s doing a great job reppin’ for the ladies:)

  16. Thank you for this article! I am 30 years old, and I have been engaging in regular 14-16 hour fasting periods Along with a ketogenic diet for almost a year. My husband can easily perform intense workouts with just a bulletproof coffee and wait until dinner to eat. On the other hand, if I wait to eat past 16 hours, I feel too foggy to do my job well. I notice that my fasting window is more challenging after ovulation, and I usually have to adjust to a less aggressive 12 hour window. I always just thought I was kind of a baby when it comes to fasting, but this helps me feel that is not true. No detrimental cycle effects noticed when I adjust my fasting window during my cycle. Cannot wait to read part 2!

  17. Great article. As others have asked, is there any information for post menopausal women for IF with a ketogenic diet? Thanks!

  18. I have always felt this intuitively and its nice to see this being highlighted here — thank you for a wonderful explanation and perspective.

  19. Could my fasting have resulted in early menopause? And now that I have stopped menstruating and am currently on HRT would fasting create issues with the menopause or not?

    1. I have the same question. I did keto and fasting a few years ago and I went through menopause (early) within a few years. I’m 44 on Monday and it’s been over a year and a half since my last period.

    2. Hi Helen – I think doing a 3-day fast kicked me into early menopause. I did a 3-day fast 2 years ago and started having hot flashes for the first time during the fast that continued on after the fast. Prior to the fast, my periods were very regular, every 28 days and then they went to 23 days. Things normalized after about 4 months, but then I was doing IF and then tried carnivore and things just did not work out well for me. Low energy, mood swings, binge eating. Then the hot flashes started coming back and I had my last period almost a year ago and I just turned 50. It’s not super young but there is definitely some sort of correlation. I’ve been looking for similar information to try to better understand how it works for those on the verge of menopause or in menopause but haven’t found much.

  20. Glad to see this topic finally delved into! I’ve felt this way for a while regarding fasting. And almost felt presure to do it from the rest of the health world, but also known it wasn’t right for me. I am a 28 yr old female with a bmi of 16 and lead a very active life. I seem to feel much better starting breakfast a couple hours after I eat, and notice I start to get migraines if I wait too long between meals, and have lost too much weight and experienced issues with my cycles when I was doing daily 16 hr fasts. I know several other women who have suffered worse from regular fasting including ammenorhea, severe depression and cystic acne. It’s so important more light is shed on the gaps in research when it comes to women’s health. I would love to see more articles discussing this. This gap in research is the cause of many women suffering, and often being told it’s normal or having their pain dismissed.

    1. Would appreciate more information about fasting for post menopausal women. I am quite a bit post menopausal, on HRT & thyroxin. I am more into calorie restriction and IF for a few days, every few weeks. Feel good, look great (for my age), but feel a loss of energy often on exertion.
      Any suggestions?

    2. Carissa, thanks so much for reading and sharing your experience with fasting. It’s all to common among young women and we agree it can cause a lot of unneeded suffering. Stay tuned for more info in Part 2!

  21. I experienced ALL the negative effects of the above while other women I know thrive on fasting. It just proves further that we are all individually different and one size does NOT fit all. Experimenting and then modifying what works for you is key. As women, we have really have to listen to our intuition and what our bodies are telling us.

  22. Thanks for addressing the issue of fasting for women, however, your article left me even more confused as to whether or not I should fast. You’ve raised more questions than answers. I am a 60 year-old, post-menopausal woman. I have less than 18% body fat and do some sort of vigorous seasonal activity at least 6 days a week. I’ve been doing 12 hour fasts for over 5 years, and, although I do experience some of the sure effects you list above, overall I feel great. I look forward to reading part 2 for more info and possibly answers.

  23. I loved this article, thank you. I am 42 and have been practicing time restricted eating (usually 18-20 hours of fasting) daily for the past year now and have only experienced positive results. Just recently I decided to try a few extended fasts (72 hours or a week of ADF) here and there and while I love the feeling of being fasted longer than 24 hours, I do have sleep troubles on the nights when I fast over 24 hrs. I have not had any menstrual disturbances yet. I get my blood biomarkers and cortisol tested every 3-6 months so it will be interesting to see if cortisol is high or hormones are off after the EFs. Any tips on sleep during fasting is appreciated!

  24. This article is absolutely answered all my questions on the subject. I have been cultivating a fasting program but find I am burning out/hormonal. Even maximising my nutritional content. I am feeling full and more energetic through the food but find I am too hungry to skip breakfast and burn out so I have replaced lunch and breakfast with green smoothies packed full of greens and life power and this is working better.
    Looking forward to part 2! Thank you so much

  25. Thanks for the update…I am a 58 year old female who has been health conscious most of my life. I’m quite active and fit; on no medications, and have been intermittent fasting for a year or more. Also, I eat a whole-food diet, I have noticed a steady increase in my blood pressure. I have just started easing off intermittent fasting (I only do 12-hour fasts through the night.) and three small meals with no snacking. Hopefully this will resolve my issue. Thanks for giving me more data!

    1. Interesting. I have been practicing IF for nearly a year 18:6. I am 51, extremely active, no medications and follow a healthy diet. I have also experienced a steady rise in my BP that was at one time considered low and is now considered high. I feel great, but this has me concerned. I never considered IF could be the cause, but it seems we share a lot in common, unfortunately the raise in BP included.

      1. I’m confused. All the other articles on your site sing the praises of IF. should we assume everything written is for men unless specified “women”? I find the information here very thought provoking and interesting but also contradicting.

  26. Very good article… I am 66 and fasting…. feel great and have been doing Keto for 9 months now….I wanted a kick start to lose 10 more lbs….feel great and am startind day 2 of my fast…slept well and feel positive!
    Thanks for this article…

  27. Are there any studies on menopausal women and intermittent fasting? I’m also inquiring about recovery options for women over 60. Thanks!!

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