Dear Mark: More On Women and Fasting

Dear_Mark_Inline_PhotoLast week, I updated an older post on women and intermittent fasting. For today’s edition of Dear Mark, I’ll be answering some of the comments and questions from that post. First, should a lean woman with a stressful life try fasting to heal her gut? Maybe, maybe not. Second, does coffee break a fast? Now, where have I heard that one…? Is a 12-hour fast a good starting point for women? What are the IF “pre-reqs”? And finally, what do we make of women who can fast successfully? Does habituation have an effect?

Let’s go:

Megan asked:

I am a 33 yo woman. I am 5’9 and between 129-133 lbs. My longest fasts have been 4 days and we’re medically indicated (i.e. I was hospitalized and not allowed to eat) due to painful flares in my Crohn’s/ileitis (I have recently switched to all meat as my worst flare left me in the worst pain of my life and was from eating veggies/fiber). I naturally do some amount of intermittent fasting (16 to 20 hours).

I am interested in longer fasting than what I do for its potential to help heal my gut, but a several things stop me. 1. I become voracious by about hour 21. I can’t seem to push through. And I have been keto-adapted since August 2017. 2. Though my BMI is in “normal” and I have good muscles, I am on the lean side. 3. Life is kinda intense this year. Yeah, yeah, I meditate and all that. But life has been very intense.

Does anyone have any thoughts on extended IF for gut healing for a lean, probably too stressed, woman?

Check with your doc first. It’s worth a try.

In one study, patients with irritable bowel syndrome (IBS) were fasted for 10 days after four weeks of regular IBS treatment. Another group continued the regular treatment. The fasting group saw improvements in 7 of 10 markers, including abdominal pain, abdominal distension, diarrhea, anorexia, nausea, anxiety, and general interference with life.

Crohn’s isn’t the same as IBS. Crohn’s is generally more serious and can result in physical damage to the gut. But the symptoms are similar enough that this fasting study piques my curiosity.

Improving gut health and reducing inflammation doesn’t require full-out fasting, though.

In obese women, severe calorie restriction (800 calories per day) reduced overall inflammation and improved gut barrier function. They also had a lot of weight to lose, and they lost an average of 15 pounds over 4 weeks. That’s quite good for a short study. It’s hard to know whether it’s the calorie restriction or the weight loss improving the gut health.

Side note: a really cool part of this study is that 14 days after the very low calorie diet, when they were back to their regular diets, the women had gained about half a pound back, but it was lean mass. They actually lost more body fat and had a smaller waist circumference than they did after the 14 day low calorie diet.

My point is that calorie restriction was good enough.

Fasting may very well work for you, but it might not be necessary. It might even be too much of a good thing, given your stress levels. Try it—that IBS study is pretty convincing—and be aware.

Micki asked:

Question: I’ve heard both, that black coffee breaks your fast and that black coffee doesn’t break your fast. Opinions? Evidence to either?

Check out my recent post on the subject. It should answer your question.

Micki wrote again:

I’ve reached the point of not trying to force any specific IF protocol other than a regular 12 hour fast every day, which is usually 8pm-8am.. If I go longer, I go longer but I have ceased shooting for any other IF time period. This is what suits me but may not suit anyone else that tries IF. We’re all different, eh?

For what it’s worth, my experience talking with dozens of women is that 12 hours is a sweet spot. Anyone (especially women) curious about fasting should start there, see what happens.

Stacey Martin asked:

Where would we find the IF pre-reqs?

It’s there in the article:

If you haven’t satisfied the usual IF “pre-reqs,” like being fat-adapted, getting good and sufficient sleep, minimizing or mitigating stress, and exercising well (not too much and not too little), you should not fast.

Fat-Adapted: You should have your fat-burning machinery up and running, as fasting places great demands on your ability to burn your own body fat for energy.

Stress: Fasting can be stressful, so don’t add it to an already-stressful life. Stress adds up, whatever the source.

Sleep: Poor sleep makes dieting less effective. It also makes you hungrier, especially for junk food.

Exercise: Too much exercise and you’ll make the fast more stressful than is helpful and hamper recovery. Too little exercise and, well, I don’t have any objective reasons. I just know that exercise and fasting go perfectly together. There’s nothing more delicious and satisfying than a meal after a fasted training session.

blah wrote:

I’m a woman, have been skipping dinners for over 5 years, going 12-16 hours with no food daily. I still consume around 2000 cal a day and weigh about 130 lb. My cycles seem to get less regular the more I deviate from this routine and gain weight.

Also if fasting was hurting fertility how do we explain India and other 3rd world countries?

The key here may be your consistency. This conditions your body to expect food (and get hungry at the right time, not before), and it improves the metabolic response to eating.

In one study, the authors actually tested the effect of breaking your eating habits by separating overweight women into habitual breakfast skippers and habitual breakfast eaters and then having them either skip breakfast or eat breakfast.

Habitual breakfast eaters who skipped breakfast experienced way more hunger at lunch, had worse blood lipids, and higher insulin levels. They had worse blood lipids and their insulin skyrocketed. Habitual breakfast skippers who skipped breakfast experienced none of these deleterious effects.

Meanwhile, habitual breakfast eaters who ate breakfast were more satiated at lunch. They had better blood lipids and normal insulin levels. Habitual breakfast skippers who ate breakfast were still hungry at lunch. Eating breakfast didn’t inhibit their regular lunch-time appetites.

Other research has found that maintaining a regular eating schedule improves insulin sensitivity, increases energy expenditure, and improves fasting lipids. Overall, sticking to an (rough, not draconian) eating schedule results in the best metabolic effects, which appears to be what you’re doing.

That’s it for today, folks. Thanks for reading, asking, and writing. Take care!

Primal Kitchen Buffalo

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

If you'd like to add an avatar to all of your comments click here!

28 thoughts on “Dear Mark: More On Women and Fasting”

Leave a Reply

Your email address will not be published. Required fields are marked *

  1. Thank you for taking the time to develop posts like this for women!

  2. 7 day water fast provoked atrial fibrillation

    anyone heard of this side effect

    1. Makes sense to me, Larry. I would think for most people fasting that long would do a number on one’s adrenals. Not a doctor, but I could see how that might elicit an afib. I once got an afib from how I responded to a cascading wall of stressful events in grad school (almost the definition of grad school), so stress is likely to play an important factor in this.

    2. Could be an electrolyte issues. That kind of dehydration can cause AF.

      1. Yes, I woke up a lot with leg cramps when just low carbing. Salt or dietetic salt substitute (potassium chloride) got rid of the cramps in about 5 minutes.

        Hence bone broth or bullion cubes are now standards or just adding more salt to your food.

        And, of course, when fasting ONE MUST DRINK extra WATER!
        when eating one gets a lot of water in the food normally. Exception if living on dehydrated food like pemmican or jerky.

  3. Hey Mark, question on fast vs slow caffeine metabolizers. What do you recommend for people like me who are heterozygous for rs762551 (A;C) as far as cups per day of coffee? Research tends to loop in heterozygous (A;C) and homozygous (C;C) into the same “slow metabolizer” camp, and it seems like risk of disease increases with even 1 cup of coffee.

    Should we give it up or no? (Hoping for the latter)

    1. I’m guessing Mark would say, “how do you feel?” Does it affect your sleep? Do you feel energized when you drink it or stressed and anxious? Just my two cents.

      1. Definitely a valid point. Tricky thing is it doesn’t have a big impact on how I feel, but I don’t necessarily trust that it makes it harmless biologically. (I’m pretty resilient to even eating crappy food and feeling fine with the occasional cheat meal.)

  4. Daily fasting (14 to 18 hours) comes naturally for me. It wasn’t always that way. Before I began eating 80/20 Paleo I was often hungry before I even got out of bed. I don’t know whether 80/20 is enough to be fat-adapted (and don’t really care since what I do works well for me), but I usually don’t get hungry now until around noon. I tend to get a headache if I wait too long to eat, so the idea of longer fasts doesn’t appeal to me.

    My suggestions (from personal experience) would be to experiment a little to find what works best for you. If you plan to try IF, start out slowly to let your body adjust, gradually lengthening the duration of your fast. If (or when) you reach a point that fasting becomes counterproductive in any way, back off to a level that’s comfortable for you. There’s no right or wrong way to do IF. It’s all a matter of what works for the individual. Bear in mind that it doesn’t work at all for some people.

  5. Wondering if maybe the mixed research & testimonials of pro/com women fasting may have to do with natural inclination. I think any fast that you have to white-knuckle through is going to produce immense stress on your body. I naturally want to eat in about an 8-9 hour window, and it is so much better for my gut problems, but my thyroid does not seem to like it. Fasting for women is more complicated than for men.

  6. I’m a bit nervous about IF. I suffer from migraines and need to eat regularly. If I skip meals, i get a migraine. But I’m heartened by the 12 hours overnight thing. That, I think I can do. Also because of my migraines I need to sleep for a constant amount of time and that sounds doable. Eventually. I’ve just embarked on the 21 day reset so not fat adapted yet…

    1. If you are not already, you should try taking at least 600-800 mg of magnesium bis-glycinate daily for your migraines…it sure helped me!

  7. For what it’s worth… this was my experience when I first discovered the work of Jason Fung (interviewed by Robb Wolf)…

    I was in a relationship that (unbeknownst to me) was about to end. I was working two jobs, and studying nutrition part time. I was 100% reliant on public transport to get around in a city with terrible public transport. My cat had just been put down, I’d just found out my partner had cheated on me, and I was doing my damnedest to maintain straight A’s at university.

    I had/have weight to lose – and have always had weight to lose by varying amounts. I had moderate success with keto, but could never get past feeling hungry. I had moderate success with the Whole30, but I missed wine, and cappuccinos, and being able to socialise with my friends without being ‘that person.’

    Anyway, when my relationship finally ended, I gained weight rapidly. In the vicinity of 8-10kgs in the space of six months. Naturally I blamed myself – I was using wine and food as a coping mechanism while simultaneously trying to figure out how to date again. So I went cold turkey from everything again, started fasting for 24 hours on alternate days – and did a 36 or 48 hour fast once a fortnight. When I did eat, I made sure to stay under about 100g carbs from whole-food sources. I weighed and measured everything to make sure I wasn’t eating 1000’s of calories unwittingly. I wore my FitBit everywhere, and started working with a personal trainer. I did cardio. I sprinted. I lifted heavy weights a few times a week. I did everything ‘right.’

    And I didn’t lose a thing.

    I went to see my doctor in tears. Thankfully, he listened, and praised me for everything I had already tried to do. He ran blood work, which revealed the following (despite everything):

    I was extremely insulin resistant (despite low carb and fasting)
    I was extremely zinc and B12 deficient (despite wholefoods, and animal foods)
    I was extremely estrogen dominant (the highest he’d ever seen)
    And I had no progesterone

    I’d stopped ovulating. Who knows which one of the pillars fell over first, but one thing was for sure – fasting was the absolute last thing I should be doing.

    My point really is that when it comes to women, I think extreme caution is needed when we consider fasting. If I didn’t have such an amazing GP, I would never have known all of the above. I would have ended up fasting more, fasting longer, exercising harder, and ultimately compromising my fertility further. I still got/get a regular period. There were no other warning signs that something was wrong. By all means give it a go, but listen when your body whispers. Don’t wait for it to scream.

    I still have those extra 10 kilos two years later, and I have no idea how to get rid of them. So I’ve stopped caring. I’ve spent so much time ‘hating the handles’ that it feels like such a waste. I’m fit. I’m strong. And I’m on the road to recovery.That’s all I care about right now. But this experience has certainly taught me that even those of us who ‘know what we’re doing’ can land ourselves in real trouble.

    1. Thank you for sharing your experience. I was “fat adapted” and feeling fit, great at 60 and then the world fell apart in a similar way for me. I have been 20 pounds higher with no reason for it. I keep thinking maybe I just need to fast and “reset” everything. However, the stress is still very real so maybe I’ll talk to a doctor and see about my hormones, etc.

      Thanks again!!!!

  8. Those IBS numbers do look promising! I think under doctor’s supervision, I could give this a try. It’d sure beat screaming into a pillow, dry heaving bile, and going through the whole flare-up routine. I am surprised by the paucity of research on fasting and Crohn’s and UC, though this study ( on Ramadan and Crohn’s/UC seems to indicate slight improvements in symptoms across the month.
    33 yo lean female

  9. Such important information. I tried the Glow15 diet and failed miserably. I pushed through 2 days of headaches, irritability, and brain fog before deciding that this was not normal or healthy, and certainly not “worth it”. Ditched that and bought the 21 Day Metabolism Reset. What a difference. This is the best I’ve ever felt and I’m slowly working my way to IF. I can now do fasted workouts and feel good going 14 hours without eating. Fat adaptation really is crucial before trying any kind of fast.

  10. Fasting is easily accomplished if you are already avoiding all dairy, sugars, grains, and potatoes. Without this habit already in place it is a far greater struggle.

  11. Regarding the question about India and other third-world countries: these are populations who have survived for many generations on sparse amounts of food, as well as periods of famine. Only those women with the lowest caloric needs and the best ability to store fat would have survived and reproduced. Unless your recent ancestors are from India or suchlike region, I wouldn’t consider the high-hunger-tolerance of these women as good enough evidence that western/Izard women will benefit.

    Note, Indian women reach normal-weight obesity and face all the dangers of diabetes and heart disease at significantly lower BMIs than those of western women.

  12. In an older post on women and intermittent fasting – I found the following:

    Some Warning Signs To Watch For

    Weight Gain (especially in the midsection)

    There were a few more things to look out for, but I am interested in these two since I think they relate to blood sugar control.

    My question: When you don’t seem to burn fat well ( for whatever reason) and you don’t eat when you are hungry because you are extending your intermittent fasting from overnight to at least 14 hours, does everybody’s liver shoot out the ‘remedy’ with gouconeogenesis, glucagon and chemistry that makes you get fat on your belly? Does this show up on my HgbA1C ?

    Female, 71 yrs old, wakefulness at 0300 consistently with low carb, over 100 AM fasting blood sugar that usually goes down with food.

  13. Hi Mark,

    Thanks for shedding light on the differences that IF has on men and women. I was wondering if you could please shed some light on “fat fasting”. From what I understand, you can steal reap the benefits of autophagy by adding healthy fats to your fast (ex: coconut oil to coffee as an extension). Is it true that these fats will allow your body to stay away from “starvation mode” making it safer to fast?

    In gratitude

  14. Hey Mark, your Q/A session on women fasting is really a boon for many that solve and clear various questions and doubts as you discussed in this post also. It’s a great work. I appreciate your blog.

  15. Do you have any studies or observations on fasting and post-menopausal women? S

  16. This may sound a little too simplistic, but I take it day by day these days. I generally eat twice a day, NOW. Used to be a B/L/D and bedtime protein shake person. My last meal is about 5:30 or 6 and then I’m done. Then I eat when I am hungry the next day which can be anywhere from 8am-11 am but generally there is always a minimum of 14 hours of fasting. I have never and have intend to do a full out fast only because it really gives me anxiety….unless I’m sick of course. I have found that IF does help with IBS for sure as my gut is less triggered. But I’ve yet to find the sweet spot regarding fasting and find that it is a very individualized approach much like the exact foods that we eat, how we train, etc. I think we have to get back to a place where instead of doing what’s popular, we do what’s proper. Paying close attention to how we feel while being open to options. Just my $.02

  17. Dear Mark

    I am a 45 year old woman who is at the start of menopause. I have recently gained and unexpected amount of weight (10kg) which I attribute to this. I suffer from subliminal stress which leads to muscular discomfort and stiffness as well as joint pain, which impedes on my well-being and ability to exercise. I feel trapped and am looking to make changes to my diet to support both hormone changes and age deterioration. I currently follow a predominantly paleo diet and am looking to eat more of a plant-based with fish and some red meat a few times a week. One of the supplements I have been looking into is taking collagen to support my joints. There are articles stating that the 5 types of collagen are essential to supplement with and there are articles saying that collagen is collagen and any type is irrelevant. I am based in the UK and so your primal collagen peptides are not available. Are you able to shed some light as to what I should be looking for in a collagen supplement?

    Thank you