Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
19 Jun

Dear Mark: Women and Intermittent Fasting

Many differences exist between the two sexes. We look different. We sound different. We dress differently from each other. We like different things. Different genres of movies cause men and women to cry (differently). And although society, media, and culture drive and/or inform many of our differences, some are inherent and physiologically-driven. For example, men and women have different biological equipment – both external and invisible to the naked eye – that change how we interact with and respond to our environments, our exercise, our sleep, and our eating habits. Nowhere are these gender differences more evident than in the realm of health and nutrition, and yet it seems that I’ve overlooked a big one: different sex responses to intermittent fasting.

Let’s take a look at a couple recent reader emails:

Hi Mark,

I’m a woman (28 years old) who followed your recent fasting series with great interest, gave it a shot, but had mixed results. Then I read this post, which mentioned your series and questioned the suitability of intermittent fasting for women. Is it true? Do we respond differently than men? What do you think of that post? Thanks!


Dear Mark,

Paleo for Women blog says that fasting may not be for women: that it’s more suited for male physiology. I have been fasting for three years and never experienced any missed periods/sleeplessness, etc. Moreover I got a handle on my mindless eating. Can you give your word on IF for women?

Varsha Tiwary

Thanks for writing in with your questions.

First of all, I really, really liked Stefani’s post. I should say “posts,” actually, since Stefani Ruper (who wrote the post linked in the reader question) also just did a guest post on Free the Animal, in which she discussed the treatment of women’s issues in the community at large. While I don’t agree with everything she said, both were quite well done.

Even though her articles – for lack of a better phrase – “called me out” (in a completely non-confrontational way), I was actually quite happy to read them. Heck, I was happy to read them because of it. After all, I’ve always encourage people to be critical about what they think they know about nutrition and fitness, and to be skeptical about what they read on the Internet – my articles included. The beauty of MDA is that it isn’t one-sided. I get constant feedback from readers that send me down new paths of inquiry, and it’s through this kind of crowd-sourced effort that the Primal Blueprint message grows and becomes stronger than it already is.

I also appreciated Stefani’s articles because they do highlight a blindspot – not just in my own series of posts, but in nutritional science as a whole. In the push to eliminate the confounder known as inherent endocrine gender differences, they’ve forgotten that real life is a series of confounding variables all pushing, pulling, poking, and prodding at the results we get. They’ve forgotten that while their results may represent fodder for publishing and accolade accumulation and hypothesis confirmation (or rejection), real live humans in normal living situations are not placebo-controlled. That women are not the same as men and respond differently to stimuli and stressors isn’t a “confounder”; it’s a fact deserving of further study! Because what are we ultimately trying to do here – put together nice, neat, peer-review-ready trials, or help real people living real lives?

Since I’m trying to do the latter, I happily accept constructive criticism. So should we all.

So, what did Stefani’s research find?

Fasting has different endocrine effects on male and female rats.

In male rats:

No matter the duration or degree of nutritional stress, male rat brain chemistry responds with similar changes. Nocturnal activity and cognition stay fairly stable, regardless of the intensity of the fast. If you push the fast long enough, males will get a little wonky and frantic, but overall they maintain pretty well. It’s like they’re equipped with the ability to handle nutritional stressors.

In female rats:

Any degree of nutritional stress (fasting or mere caloric restriction) causes increased wakefulness (during the day, when they normally sleep), better cognition (for finding food), hyper alertness, and more energy. In short, female rats become better at finding and acquiring food when they fast, as if their bodies aren’t as well-equipped to deal with the stress of going without food. They also become less fertile, while the males actually become hornier and more fertile (probably to account for the females’ plummeting fertility). Ovary size drops (bad for fertility), adrenal gland size increases (which in rats indicates exposure to chronic stress), and menstrual cycles begin to dysregulate in proportion to the degree of caloric restriction.

In humans, the male-female fasting literature is quite scant, but Stefani also found considerable differences beween the sexes, when data was available:

  • One study, which I’ve cited before as evidence of a benefit to fasting, found that while IF improved insulin sensitivity in male subjects, female subjects saw no such improvement. In fact, the glucose tolerance of fasting women actually worsened. Ouch.
  • Another study examined the effect of alternate day fasting on blood lipids. Women’s HDL improved and their triglycerides remained stable; men’s HDL remained stable and their triglycerides decreased. Favorable, albeit sex-specific results.
  • Later, both obese men and women dropped body fat, body weight, blood pressure, total cholesterol, LDL cholesterol, and triglyercides on a fasting regimen. These people were obese, however, and perimenopausal women were excluded from the study, so the results may not apply to leaner people or women of reproductive age.

I figured I’d look through my other recent fasting posts for data on female (preferably pre-menopausal) responses to fasting. Here’s what I found:

  • In the only heretofore extant human study on fasting and chemotherapy, seven females (including a 44-year old woman who was likely premenopausal, given when menopause usually onsets, though it wasn’t explicitly stated) and three males found that IF improved their tolerance to and recovery from chemotherapy. Takeaway: male and female (mostly middle aged, though that’s the population that generally gets cancer and undergoes chemotherapy) chemotherapy patients appear to benefit equally from IF.
  • Although both men and women displayed greater increases in VO2 max and resting muscle glycogen concentration in response to fasted cycling training, only men showed greater skeletal muscle adaptations when fasted. Women had better muscle adaptations when fed. Takeaway: fasted endurance training, then, may work better for women than fasted weight training.

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.

As I alluded to earlier, this is what I love about this open forum we call the Internet: the fact that if you leave something out, or overlook a key point, someone will call you out on it, most likely publicly. When that happens, you grow despite yourself. If not for Stefani’s posts, I may never have taken a closer look at the inherent differences in men’s and women’s metabolic responses to fasting. I certainly receive enough feedback from female readers for whom fasting has been helpful, so it’s good to see another side.

To sum things up – if such a thing can even be done – and answer the questions in the intro, men and women have inherent metabolic and hormonal differences, and it’s evident that these differences in part determine how we respond to a stressor like intermittent fasting. I’ve never prescribed intermittent fasting as a requisite piece of the Primal lifestyle, but rather as an adornment, a choice, a potentially therapeutic strategy that each individual must test for him or herself. Although my recent series on fasting might have thrown some people off, I want to reiterate that I am not a huge IF guy. For myself, I generally fast when it makes sense – if I’m traveling and good food isn’t available, if I’m just not hungry, stuff like that. I periodically do 16/8 or 14/10 (i.e. eating in an 8 or 10 hour window) and find it works great for me because I am fully fat-adapted. But even I don’t hold rigidly to that. It’s not for everyone. And that hasn’t changed.

So who should and shouldn’t consider fasting? Have my recommendations changed?

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. The pre-reqs are absolutely crucial and non-negotiable, in my opinion, especially the fat-adaptation. In fact, I suspect that if an IF study was performed on sugar-burning women versus fat-adapted women, you’d see that the fat-burning beasts would perform better and suffer fewer (if any) maladaptations.

I would also caution against the already lean, already calorie-restricted woman jumping headfirst into IF. I mean, fasting is ultimately sending a message of scarcity to your body. That’s a powerful message that can get a powerful response from our bodies. If you’re already lean (which, depending on the degree of leanness, arguably sends a message of scarcity) and restricting calories (which definitely sends a message of scarcity), the response to fasting can be a little too powerful.

I’d also say that daily fasts, a la 16/8 or even 14/10, run the risk of becoming chronic stressors and should be approached with caution by women. Same goes for ultra-long fasts, like a 36 (or even 24) hour marathon. Most of all, though, I’d simply suggest that women interested in fasting be cautious, be self-aware, and only do so if it comes naturally. It shouldn’t be a struggle (for anyone, really). It shouldn’t stop your cycle or make it harder for you to get pregnant. It should improve your life, not make it worse. If you find that fasting has those negative effects, stop doing it. It should happen WHEN (When Hunger Ensues Naturally), if it happens at all.

I’m not going to say that women should or shouldn’t fast. I’ll just echo Stefani’s advice “to look at options, to be honest about priorities, and to listen to one’s body with awareness and love.” Frankly, everyone should be doing that, but with regards to fasting, it looks like women should probably hew a little closer to her words.

Of course, if I had to make one minor quibble with the content of Stefani’s otherwise outstanding posts, it would be her source for the number of unique visitors Mark’s Daily Apple gets each month. Nowadays, we’re actually getting closer to 1.5 million monthly uniques, not 250-300,000… but who’s counting?

That’s it for me, today. What about you? If you’re a woman who has tried fasting, or know someone who fits the description, let us all know about your experiences. I’m intensely curious to hear from as many of you as I can. Thanks for reading.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Oh, and I have a physically-demanding job too. Mark, I wish you’d write something about those kinds of jobs since many of us are not sedentary office workers, and how that fits the Paleo lifestyle.

    MyrrMade wrote on August 10th, 2012
  2. I was wondering if diet drinks are allowed during IF? Thanks. Also can I use sweetener is my tea/other drinks? Thanks.

    sarah williams wrote on August 11th, 2012
  3. This is probably a dead thread, but I just found it.

    I don’t know if anyone has mentioned this, but if you want to do a large study on women and fasting, you should do it during women who fast during Ramadan.

    During the month of Ramadan, Muslims abstain from food and drink (not required in IF) from sun up until sun down. My husband’s entire family has done this their whole lives with the kids starting around the age of 6. None of them report any of the effects Stephani is talking about (which doesn’t mean they’re not really happening).

    I’ve done it and the only problem I have is that I work and I can’t stay up all night to eat, so I end up not getting enough calories and I have trouble not drinking any water during the day. However, beyond that, I don’t have any other problems as a woman. I’ve done this fasting in my 20’s and 40’s.

    The point is, if you want to know what happens to women when they fast for a relatively long period, studying women fasting for Ramadan is probably a good idea.

    Kat wrote on August 17th, 2012
  4. Benn doing IF for 5 years…no problems. One thing I must say is when I go from 2 meals a day to one meal a dya during my periods I gained less weight at this time and the weight that I did gain came of easily post menses.

    mary titus wrote on August 18th, 2012
  5. I’m a post-menopausal female, and a few years ago, I tried IF. After maybe 24 hours without food, I broke my fast and kicked off a lovely week-long bout of intense gallbladder pain and vomiting. It took a few months to return to normal, and I’ve been careful not to fast more than 12 hours or so since.

    Pia M. wrote on August 19th, 2012
  6. Very interesting comments above and of course great article by Mark.

    As for me, I am a 28 year old female tipping the scale at 112 pounds. I did the IF for two weeks. I ate in an 8 hour window and fasted 16 hours. My results…

    I ALWAYS felt hungry, my body never really adopted. I gained about 3 pounds on the fast (not my intent). My goal was to help my body the proper rest from digesting all the food I ate. I was hoping I would feel more alert, be in a better mood, and increase my weights while I lift in the gym. I didn’t see any difference.

    I am back to eating my first meal around 8 or 9am and eating my last meal around 5 or 6pm. I might sneak a small bite of chocolate around 8pm but very rarely. I feel way better and focused on this schedule. I eat three large meals and 1 snack in the middle of the day.

    The results for IF is all over the board. I’d say, give it a try and if you like the result then go for it. If not, then you didn’t sign a contract with Satan so go back to your normal routine.

    Hannah wrote on August 21st, 2012
    • So you went from an 8 hr feeding window to a 9 hr feeding window? how is that much different.

      andria wrote on February 19th, 2014
  7. I would just like to represent myself. I have been primal for about 2 months. I am 25 and probably very fertile, and whenever I think about fasting, I can feel my body saying NOOOOOOOO. Some inner voice is telling me it would create stress, at least at this point in my life. Besides, I have lost 20lbs and am still losing, so I guess I don’t see the point of IF.

    Ashley wrote on August 21st, 2012
  8. Hi Mark! Great article, thank you for your well-researched content. Back in Feb I followed a daily 14/10 IF protocol in conjunction with heavy lifting for 30-days. As you can imagine, it stressed my body to the point of hormonal dysregulation and has required significant time to recover from. Although I’ll never partake in this particular method of IF, I still occasionally enjoy a 14-18hr fast. I love the science behind IFing and am still very curious about the differences experienced by men and women. Again, thanks for the great information! Keep it coming

    Mae wrote on August 21st, 2012
  9. all i wanna know is if the differences are psychological or physiological. i would hate to gain weight on IF!
    if it was psychological it could just be that many women are apparently conditioned to turn to food as their comfort – versus if there are actual hormonal differences then that can’t be helped i guess

    i want to lose about 10 to 15 pounds and maintain it. i’m pretty sure i have a high metabolism so this is my first attempt in my 20 years at dieting but why not go for the best – and IF does sound like the best!

    Dill wrote on August 29th, 2012
  10. I did 16/8 daily fasting for about 6 months, tried 20/4 fasting for 6 months, tried a 3 day fast once (would not do it again) and have been doing IF now twice a week for 24 hours at a time for about 2 months. I have GI issues (a physician recently called it mind-gut, also acid reflux, and other things).

    IF has helped quite a bit. I find it much less stressful than dieting. That’s why I find it interesting that there were stress symptoms in women who fasted. I think some people psych themselves out thinking that IF isn’t healthy! Some people freak out and think they’re going to die or something without a day of food, or they have some disorder. My boundaries are that I never fast for more than 24 hours, once or twice a week, never two days in a row, and I end the fast when I get true hunger at any point. IF makes perfect sense to me and I like the break for my system. Not only do I save big on grocery bills but also it opens up a lot of time during the day and my nights become more efficient. I’ve lost 35 pounds in the past 2 years and the scale keeps dropping. I have 20 to go and will continue with IF, pilates, yoga, and biking and see where it all takes me. Good luck in your own journey. Like everyone else said, listen to your body!

    K Cody wrote on September 6th, 2012
  11. Anybody out there female, middle-aged, menopausal? I’ve been doing IF for about a month now, and have tried several permutations — 2 consec days/wk; two split days/wk, 3 split days/wk — and half lost 1/2 stone (7lbs). I also workout 4 hours a wk, including interval training, free weights and calisthenics. I’ve noticed astounding muscle gain (it really IS remarkable!), but last week I had a hormonal meltdown. Like PMSx400%. Severe seratonin drop; felt suicidal, weak — high cortisol, extremely irritable, and massive migraine. Although the headache has now receded and I’ve recovered from the emotional drop, I remain extremely fatigued. Any ideas from anyone? Should I stop? What might be causing this? Should I go on with modifications? If so, what sort? Any ideas welcome. I’d really like to go on with fasting –I’m losing the weight around my middle, looking younger and building muscle. As well, occasionally I feel better than I have in years.

    And then, occasionally, I feel worse than I ever have in my life, except postpartum.

    Dawn wrote on September 9th, 2012
  12. Dear all,

    I am a 36-year old woman. Today I finalized Fasting as recommended by Dr. Med. Hellmut Luetzner.
    Fasting according to Dr. Luetzner is a 8 day program during which I strictly did not eat for full 5 days (day 2 to 6). The first day of the program was to get the body and mind into fasting mode, I was allowed to eat raw fruit, veg and nuts; the second to sixth day consisted of tea, tea and even more tea, a glass of juice, and half liter of veg broth. During the last two days, you can eat things like a proper soup with veg in it, some fruit etc. I was motivated throughout the program, however I have to admit that I felt increasingly dizzy and physically weak; mentally I had tons of energy. I was able to concentrate for hours, hardly needed any sleep, and was in a really good mood; usually I get angry easily and I am very impatient, however during the IF I was really calm and at ease. Today I was finally able to take a bite again, and I am feeling miserable. After every tiny bite of food, I need to find the nearest toilet to vomit. I already ate twice today, with the same end result.
    I had fasted before, around 7 to 8 years ago, and I remember that I had tons of energy to spare, however I did not have any difficulties.
    The aim of fasting was to detox my body. As a positive side effect, i lost only 1.8kg this time, and around 5kg last time.
    Hope this helps.

    Sandra wrote on September 11th, 2012
  13. I’ve been trying intermittent fasting for two weeks now, and find myself stuck in a psychological rut at the minute unfortunately. When I put my head to fasting I can REALLY do it, and dont find it that hard,and find myself feeling little pangs of joy/self pride in the middle of the fasts at my progress, and generally more appreciation for what it actually means to be hungry. Hpwever the last two weekends ive let myself have a treat at the end of a fast because of unavoidable occassions and the junk calorific food that generally accompanies such occasions. And… it just went out of control! 1 “treat” turned into 36 hours of bingeing (im talking alcohol, pizza, chocolate cake and chips to name but a few) It’s like the minute i let myself taste a little bit of indulgence i CANT stop. this switch turns on in my head and i dont stop unitl i feel physically sick to the very core from stuffing my face. the first time i followed it with a 36 hour fast and felt a bit better about it. this time, i dont want to do such a long fast b/c i want to do work over the wkend and need energy for it…. but i just want advice on how to get out of this cycle of successful fasting/ healthy eating and savage eating because i have at least a stone and a half to lose before my GW is reached. Please offer any advice its really getting me down.

    Michelle wrote on September 14th, 2012
  14. I find this interesting.

    I have been doing a variation of IF, I suppose. I am 23, female. I do not do well with long fasts, I will literally eat anything and everything that is not nailed down when it is over (and maybe some things that are nailed down.)

    I have been waking up in the morning, having green tea, working out without any food in my belly, then waiting between 2-3 hours to eat my first meal. WORKS LIKE A CHARM

    My body fat percentage has just been falling. My appetite is decreased, and my energy is increased.

    For any women, or men for that matter, who do not do well with long fasts- give this a try. It’s wonderful..

    Maegan wrote on September 18th, 2012
  15. Hi, here’s my story. I am a 54 year old female. I have been doing IF for exactly one year. I generally fast 3-4 days a week. 18-20 hour fast with 4-6 hour eating window. I work out 2x week with heavy weights. I am 5’6″ tall and have gone from 151 lbs at start of IF to 135 lbs today. Body fat percentage has gone from 24% to 21%. I have lots of energy during the day and I sleep well at night. I will continue to eat like this for the rest of my life.

    Nan wrote on September 19th, 2012
  16. I fast intermittently. And I do it regularly (about 1-3 times a week). It’s come naturally to me, and the pounds keep flying off. I am however, not active, but I’ve dropped 30lbs so far without much difficulty.

    I keep my calories relatively low, and eat a clean diet on the days that I am not fasting.

    Karen wrote on September 24th, 2012
  17. Stefani Ruper is WRONG!

    Watch my YouTube series on why she is wrong!

    Jason wrote on September 29th, 2012
  18. 36 yo female, changed from plant based to paleo 3 months ago. I already ate a very clean, high veg diet but adding protein and removing the rest of the gluten free grains has drastically improved my digestion and energy level. I have just started playing with IF because I have 10 stubborn lbs to lose (18 month old baby) body fat is 19.5%, but all in my hips! Would weight lifting combined with IF make it more effective…any resources that you can point me to?

    Melanie wrote on October 3rd, 2012
  19. Hi, I’m 5’3, 120lbs. I gained 20 lbs;-(! Help! I need to lose 20lbs to fit back into my clothes.grrr. I’m confused. Which is better, a water fast or IFing? If I fast while drinking water alone, will I lose a lot of muscle??? I read an article saying I should do a water fast for 2 weeks to acheive my goal. I believe the master cleanse(lemon, cayenne pepper and maple syrup) and juice fasting is a bad idea, due to carb and surgar content(I also did both, no offense to blueprint cleanse,lol). I suppose pricy juice fasts are advantageous for people who are already at their goal weight…


    Lauren wrote on October 9th, 2012
    • Hey Lauren, first of all don’t worry. Lots of stressing about food can actually put your body into emergency mode and make you store fat and gain weight. I have tried a water fast and IF. A water fast can be very intense and most suggest having supervision if you are going to do more than 3 days. You pretty much need to stay at home and rest non-stop, and also you very well may not be able to think straight, so even working from home or getting projects done may not be feasible. I only did 3 days and I won’t ever do it again. IF gives me better results and I don’t feel weak or have to interrupt my life. It’s pretty simple. Only drink water for 24 hours twice a week, never twice in a row. You can eat every day if you plan it correctly. My husband and I eat dinner from 6-7pm the night before the fast, then eat again at 7pm after the fast. Don’t go under 7000-8400 net calories a week (add calories for exercise). Your body will eat it’s own muscle if you fast for more than 24 hours or under eat calorie wise. I don’t think the master cleanse is a good idea either. Juice fasts are not my thing for the same reason, you give your body somewhat of a rest but not truly. Good luck, I’ve lost 45 pounds so far and I’m on my way to 15 more.

      K wrote on October 9th, 2012
      • K, did you lose more weight water fasting? Thanks for your response;-) Lauren

        Lauren wrote on October 9th, 2012
        • Hi Lauren, no I did not sustain the weight loss with water fasting. I only lost three pounds and gained them right back. I would not recommend it. The vast majority of weight goals can be achieved through diet. My daily food intake consists of 5 servings veggies (3 of those dark leafy vegetables), 3 servings fruit, and protein/fat- always a generous portion of essential fatty acids (hemp every day and then either fish or lean meat for dinner), everything organic, 2-3L water, one hour of low impact cardio (cycling), enough strength exercise to where I get every major muscle group to the point where I cannot do another repitition (yoga/Pilates weekly), 30 minutes sunshine, and probiotic supplements. I used a kitchen scale to measure servings for a while to learn servings and now I can eye ball it. I pretty much cut all dairy and gluten due to allergies and don’t eat processed foods. Bon chance!

          K wrote on October 9th, 2012
    • Please don’t do a water ONLY fast. Starving yourself with water is not the solution and will lead to over eating later. You can either IF or do PSMF which is a protein sparing modified fast. That’s a day you go very low calorie by only having protein with some fish oil and greens. Typically around 1,000 calories. I would’nt do that for more then one or two days at least and wouldn’t do any kind of exercise those days unless its very early in the fast and something low impact like walking or swimming.

      Frank Sabia wrote on October 9th, 2012
  20. I came across your article after hearing that woman should stick with a 14/10 IF period and wanted to research why this is. I am a 21 year old (obviously premeniposal) female, very active–crossfit 5-6 days a week along with rock climbing/hiking/yoga. I do not know my exact weight or BMI but I believe it is around 140 at 5’4″ and 20%BF.

    I was so curious because I recently started IFing and have LOVED it, but 14 hours seemed really short to me. I generally lean more towards a 16-18 hour fast and always prefer to train fasted; I perform my best and may even say my recovery benefits from it. That could just be the primal eating though :).

    I had eating disorders for years (progression of exercise bilemia to anorexia to binge eating) and have spent the past few years overcoming the psychological and physiological effects. I have only been IFing for a couple months but for the first time food does not control my mind and I eat WHEN.

    So far no negative effects-although I have a hard time sleeping more than 7-8 hours a night (but this is always the case). No need for an afternoon nap nor do I feel foggy. Menstrual cycle normal. I just hope that this IFing isn’t too good to be true!

    Kim wrote on October 17th, 2012
  21. Last year I went a few weeks of alternate day fasting. Not only did I not lose weight, but after I stopped doing it completely my body gained 10 pounds eating how I normally ate before it. I still have on the extra 10 pounds and my body seems pretty resistant to getting it off. Maybe a 2 day a week fast would have worked instead of every other day, but all I know is that it messed something up for me that I hope can be fixed!

    Megan wrote on October 25th, 2012
  22. I will say, though, that even though IF doesn’t achieve weight loss for me…fat FASTING does. You all know about a “fat fast”, right? (Dr. Atkins wrote about it in his book)–90 percent fat, 1000 calories a day through 4 to 5 mini meals of macadamia nuts,cream cheese, etc… My body gets lean super quickly doing that but I seem to be annoyed more doing it, maybe because it’s easier to not eat at all. I have been dreading doing it, but I have to do something to get this weight off from IFing!

    Megan wrote on October 25th, 2012
  23. Oh, I forgot to mention…I just turned 30, mother of 3 (not sure if having babies changes anything but probably, everything seems to matter!) and I’m a size 10 and pear shaped. I have been doing kettle bell swings a couple times a week (30 to 50 swings) and that has made my shape more pear-ish than usual, but that’s for another post.

    Megan wrote on October 25th, 2012
  24. A little late to the comments here, but I’d like to share my experience because many of the comments above made me feel much less alone and crazy.

    I’ve been a natural IF’er my whole adult life. The minute I got to college, I quit eating breakfast and lunch. College roommate’s slogan for me to this day “she doesn’t eat during daylight.” You cannot imagine the grief I’ve gotten for this. I’ve also always been a natural low carber.

    Yet, I eat when I’m hungry. Yesterday morning, I was super hungry so ate some leftovers at 5 am.

    My “normal” IF is 24 hours, 7 days a week. I’m 45 YO, pre-menopause, 5’7″, about 123 lbs.

    Fascinating, I know. The other two tidbits I’d like to offer are that I’ve realized my parents were pretty similar: Very light breakfast, never ate anything else under dinner. My husband has sort of naturally followed me to eat something smaller mid-morning and then dinner.

    It’s not something I think about. I’ve made my peace with the “social lunch” and eat to be polite. Only to find out I’ve doing something that’s “a thing!”

    Juli wrote on November 9th, 2012
  25. I have been sooo happy IF’ing. I’ve actually hit a weight that I never could before even on a low carb/high protein diet.

    I realize that I used to do this as a kid – I would never eat in the morning.

    I make sure I don’t eat too much when I break the fast so I don’t get a tummy ache after. Yes, I am a female and I’m glad I didn’t listen to the IF naysayers!

    Lacey wrote on December 13th, 2012
  26. I’m a pre-menopausal woman and I have been losing weight taking the adapted form of 5:2 fasting as advocated by Dr Michael Moseley. I eat 500 calories on 3 days a week (not consecutive) and eat normal ( not binge) the rest but that means classes of wines, desert sometimes and YES allelujah – carbs.

    It is really easy to limit your intake to 500 calories and not feel hungry – there are excellent filling soups that come in at 150 calories a serve, a two egg omelette is about $175, grilled fish and salad is also an option – hell there are lots of options

    And it works for women.

    Anne wrote on December 17th, 2012
  27. I find that the fat loss from my boobs is accelerated during IF :( compared to regular diet and exercise. Has anyone experienced that?Otherwise its great

    Dee wrote on January 4th, 2013
  28. I don’t IF intentionally. However, I have noticed a pattern in my own eating habits over the years. I go through periods where I have a very large appetite and want/need to eat a lot (prolly close to 3000 calories a day) and periods where I eat nearly nothing (about 1000 calories a day), one point in college my roommates thought I had developed an eating disorder. I can’t explain why this happens, and I cannot pinpoint when I start my low calorie intake (stress, sleep habits, happiness, etc). I am trying not to sink I to the lows as I am breastfeeding my LO, but it still happens. I think this goes in line with our DNA make up that Mark was talkin about, times where food is scarce, times when food is in abundance.

    Lizz wrote on January 7th, 2013
  29. You wont gain FAT unless you eat too much! If you eat more cals than you burn – in a eating window of the day at 6-12 hours OR if you don’t do IF you eay too many cals at the end of the day you get same result – a cal is a cal! So if any of you gained wieght and in bodyfat at IF you are eating junk when you finally can eat! Then IF isn’t for you if you can’t control it after a fasting period!

    Maria Helding wrote on January 11th, 2013
  30. I just wanted to add something since I commented a couple times already about having a hard time fasting. I am fairly lean now (under 12% bf) and have been for about a year and a half. Prior to that I had been over weight most of my life and never this lean. I found I could easily fast when I had more body fat. I’ve found that it’s hard when I am lean.

    I think it comes down mainly to the difference between intermittent FASTING and intermittent FEEDING. If you mostly don’t eat, then eat during a small window day after day it’s going to be hard on you and at some point you will feel like crap. I made the mistake of doing this and I was fine until I got lean. I also workout really hard, and long workouts, even though I am not a competitor. I just love both lifting and running… and I mean LOVE both and have for over 30 years.

    If you are a lean athlete and you intermittently FEED (mostly fast) or eat too low for your level of work and leanness, yes you will feel like crap. If you are a lean athlete then you can eat low if you don’t work hard, or you can work hard and not eat low, one or the other and not both.

    Not that there are not other hormone issues for some people but in general I think this is the case.

    Roberta Saum wrote on February 8th, 2013
  31. Hi,
    I’ve been following Mark’s Daily Apple for a few years and went Paleo about 3 years ago. I also had a lot more energy (at first) but about a year ago I noticed my hair was getting much thinner and falling out. It happened really gradually (I didn’t fast, only no carb and practically no sugar ever) so I only noticed it late. I do believe there is a hormonal link, since many high starch vegetables, beans and legumes contain Phytoestrogens, but I came to another conclusion as well. Just for the record, this is a speculation, but it makes sense to me. I started taking Biosil (a product that promotes hairgrowth) and after a little research I found that the main component of this product is Orthosilicic acid (OSA). OSA is found in many plants (vegs, fruits) but the highest concentration is found in grains and beer (which uses grain fermentation). I also noticed I just couldn’t relax anymore, even though I practiced yoga and meditation (maybe going Paleo was affecting my serotonin levels as well?) and my muscle strength decreased (even thoug I ate high quality protein – all organic – daily) I’m now eating grains again but not without soaking them first (I use Sally Fallon’s book, Nourishing Traditions for recepies). There may be more to it than that, but I just wanted to share my story so women are aware that there might be down sides to going totally grain free.
    In any case, I wish to thank Mark for his excellent blog. I refer to it very very often and really love it. Thanks a lot for all the energy you’ve put into this!

    liesje sadonius wrote on February 26th, 2013
  32. For me, fasting once a week isn’t a problem. I actually feel much better 10 hours into a fast than I usually do on a regular eating-day. But I can’t exercise on fasting days, or even if I’ve just skipped a meal immediately before.

    I have noticed with my metabolism that it’s highly sensitive to the amount and type of exercise I do as well – right now I’m weight training every other day, and don’t really get hungry at all, but if I’m weight training or running 6x a week like I usually do, I’m ravenous. If I haven’t worked out at all in three days, a six inch Subway sandwich feels like far too much food and I’m not interested in eating the rest of the day.

    Kylie wrote on March 20th, 2013
  33. For some reason, there is no way to “Reply” to the 41-year-old female pro-fitness model, chef and yoga instructor’s comment about her – in her words – “positive” experience with low calorie intake and fasted training (her “thriving on 6hrs. of sleep, mental clarity and increased ability to multi-task). So my reply is ending up here randomly. But I couldn’t help but have deja vu when reading her experience. Didn’t the study that Mark just quoted state:
    “In female rats:

    Any degree of nutritional stress (fasting or mere caloric restriction) causes increased wakefulness (during the day, when they normally sleep), better cognition (for finding food), hyper alertness, and more energy. In short, female rats become better at finding and acquiring food when they fast, as if their bodies aren’t as well-equipped to deal with the stress of going without food. They also become less fertile, while the males actually become hornier and more fertile (probably to account for the females’ plummeting fertility). Ovary size drops (bad for fertility), adrenal gland size increases (which in rats indicates exposure to chronic stress), and menstrual cycles begin to dysregulate in proportion to the degree of caloric restriction.”

    Umm, Michelle…doesn’t this sound familiar? If you have to do this to yourself to get down to the 8% required to win these events, then perhaps the “fitness” competition should be more aptly named…

    Being in the “fitness” industry myself, I tire of the increasing disconnect that is happening between the world of fitness and the world of health. “Fitness” has become more and more about fitting into a certain look, no matter the consequence to your health. Unfortunately, the vast majority of people don’t see this.

    Kettlebelle7 wrote on March 21st, 2013
  34. Hi guys,

    I apologise if this has already been asked and answered, I did try searching but couldn’t come up with anything.

    I’m trying out the Eat Stop Eat method of fasting (24hrs once or twice a week) and was just wondering whether it is advisable to fast for 24hrs during your period?

    It seems to me that it wouldn’t be a good idea due to the blood/iron loss and general grumpiness that accompanies menstruation, but is there any actual data on this? How do the rest of you approach it?



    Emma wrote on April 30th, 2013
  35. I’ve always considered myself an IF dropout. I have a seriously difficult time going beyond 10am without eating. I’ve tried 5:2, and IF. I get that hyper-alert thing going where I can’t settle down and concentrate. I know that hunger comes and goes, so I can wait out the hunger pangs, but I can’t fix the restlessness.

    I never really lost weight or saw major differences in my blood sugar either.

    Am I fat adapted? I have been low carb for about 10 years, but I’m not someone who produces a lot of ketones.

    I am 54 years old and finally into menopause, or post-meno.

    To be fair, I think there’s something wrong with me metabolically. I have extreme difficulty losing weight.

    NancyM wrote on May 1st, 2013
  36. Chiming in to say I started IF a few weeks ago after watching the Mosley/BBC documentary. (5:2 – 2x a week, 500cal dinner only. I drink loads of green and herbal teas thru the day until then, then right before dinner I usually make a cup of organic broth just for something savoury. My boyfriend has much less to lose but was curious to try it to improve muscle definition in his abdomen (the only place he needed to really lose anything). In the evening, I prepare a 500 calorie meal, always lowcarb (tonight for instance was spinach, tomato and cucumber salad with balsalmic dressing and grilled halloumi), and my SO has his with extra crispbreads or portions to add the additional 100 for men.

    As for me, I’d previously lost about 21kg (50ish pounds, I believe?) over two years of what I’d say was lowcarb/primarily paleo eating (I say “primarily” because I did continue to eat organic yoghurt almost daily and relied on the odd Atkins bar when in a bind)….but weight loss had stalled after 21kgs, and I have felt – even though I’ve kept it off – that I needed to shake things up a bit. I also felt I was eating healthy calories overall, but still too many of them. (I don’t eat junk food and I rarely touch sugar or wheat – but calorically its easy for me to get too many, since many beneficial foods that I rely on – coconut oil, macadamia nuts for instance – are not exactly low-calorie. I take a few supplements daily (based on the Jaminets’ “Perfect Health” recs – Vitamin D and K2, a B complex, a probiotic, Magnesium, Copper, etc).

    Still – I feel these choices laid a good foundation for IF, because I don’t have issues with blood sugar “crashes”, headaches, I sleep very well if not better since I started this… when I see irritability/headaches/blood sugar crashes being described by people for whom it’s not working, I would only question if that could be in part due to nutritional deficiencies or bad diets.

    I see a few stories now and then about people who experienced some issues like this – but then in the same story talk about the gorging on “feed” days, describe junky or carby meals, etc – and I have to wonder if IF has gotten a bad rap when in truth, other factors can be the root cause. I feel like my body isn’t needing anything because nutritionally, I’ve given it what it needs and fuel-wise, it’s already fat-adjusted and not seeking carbs for a quick fix.

    Of course, we’re all different, and I know what works for one won’t for another – but I for one find the research compelling not just for weight loss but improving quality of life as we age and as long as I’m feeling better on it, and feeling my body streamline somewhat, I’m all for it.

    For my part I’m in my 40s, have about 13kg (30 lbs or so?) left to lose and IF has, at least so far, been not that hard at all.

    For what it’s worth, my 2p/tips:

    I deliberately choose my 2 busiest days to fast until the small dinner meal, Tues and Thurs

    I keep lots of herbal and green teas around to enjoy through the day – helps me stay hydrated, keeps my taste buds entertained.

    I have a cup of 5cal broth before the evening meal, takes that edge off if I’m hungry so I don’t eat too quickly, and it tastes surprisingly good.

    On my “feeding” days I make an effort to eat normally and I actually use an app to track calories even on THOSE days so I am sure I have a “feel” for what my suggested goals actually amounts to.

    on Wednesday and Saturdays, we opt for more indulgent foods but keep the day’s food within an 8 hr window and usually just have 2 meals that day.

    KMD wrote on May 2nd, 2013
  37. I stumbled across this website looking for answers because i started fasting last month one day a week and I’m talking real fasting, so nothing for 24-36hrs; one weekend i did 48 hrs and i’ve been doing it for spiritual reasons as well as im trying to lose 5 lbs BUT im now 1 week late with my cycle. I know im eating enough about 2000 cal/average on regular days and i workout 5x/week averaging around 35miles a week. I’m hoping that my cycle goes back to normal since this is a new change for my body. I really like the benefits of fasting so i was hoping to find some reassurance that my cycle will return to normal eventually..I don’t want to

    monica wrote on June 15th, 2013
  38. I am 51, female, postmenopausal (hysterectomy at 41…still have ovaries). I tried fasting recently for the first time. I was 115 lbs and 5’4″-pretty lean already since I am well-muscled from climbing a lot. I’ve always disliked eating first thing in the morning (though I usually wake up early and alert). I’m totally fat adapted, eating 70 percent fat, 15 protein and 15 carbs. I can workout easily with no food all day, and-like Mark-do so when I feel like it. Also I have IBS and do poorly with solid food first thing. So typically I have about 400 calories of heavy cream when I arise at 6 a.m. ish and then eat eggs and/or meat about 10 a.m. By eliminating the cream I was able to extend my fast from 10 to 14 hours daily. I tried this out of curiousity and also because I wanted to get just a bit leaner as an advantage climbing. (On my 11d project, all one’s weight is hanging from the tiniest little edges in the rock…it’s finger tendon intensive and strength to weight ratio is critical.) What I found was I quickly and easily lost 5 lbs and at 110lbs I have nicer definition in my abs. I haven’t made progress on the climbing project due to a shoulder injury but my IBS was much improved. I suspect this is due to consuming much less cream… the cream has some lactose, which worsens my IBS. But I can tolerate cream and any food better after a longer fast-if I force food too early, when I’m not hungry…diarrhea. I noticed no other changes from this form of fasting. So now I’m holding steady at 110, consuming less cream early in the day and more beef later and just deciding each day, cream in my tea…or not. I like knowing I have this tool to lean out when I want to, and the insight gained on managing my IBS.

    Danielle Thalman wrote on June 19th, 2013
    • Thanks for your post. I am 58, post meno as well. I have been fasting after dinner and not eating anything until lunch the next day. I have a cup or two of coffee with GF butter and coconut oil (1 TBS of each blended w/ coffee in the blender) and have been happy with that. I’m going to see about getting fat adapted and find out what is involved or if I’m close already. I like the idea of eating one or two times a day. I just need to add in some exercise somehow. I think that I will have to get up at 4 to fit it in, I’m a bit “done” when I’m finished feeding the family after work so bed is calling my name by then, wake and start over at 5…. maybe I can just NOT sleep that last hour and do something then.

      2Rae wrote on June 19th, 2013
  39. I’m 39, over weight, mostly primal – feel great when avoiding grains etc. Since March been fasting 2 or 3 days (not a complete fast normally 600 odd kcals in the day) I can now do a full kettlecise class of an hour with nothing in the “tank”(which inc. warmup/ stretches after) and happily feel great afterwards! Don’t really feel hungry till 1pm ish

    But the biggest thing is that my 8 day monthly has changed to 5 days !

    Misbehave wrote on June 19th, 2013
  40. What about Blood Type? I’m on the Eat Right For Your Type Diet, I’m an O-Hunter, which means I eat meat. I’ve been doing IF with much success. I do a 36 hour fast on Wednesday and a 24 hour fast on Fridays. Been losing weight on this regime.

    I wonder how fasting plays into this type of diet.

    Christine Calabrese wrote on July 7th, 2013

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