Women and Fasting – Part 10

posted in: Fasting, Health and Nutrition | 51

Not surprisingly, the use of fasting for weight loss has a long history, since it’s, kind of, like, obvious. I mean, everybody understands that if you do not eat, you are highly likely to lose weight. Duh. Which makes it even more surprising how much people fear missing even a single meal, let alone fast for a prolonged period of time. They think that fasting (not eating) will make you fat. That’s kind of like saying that splashing water on your head will dry your hair. That’s modern dietetics for you. Kind of a Bizarro world.

There are still many doctors who argue that eating sugar is not bad for type 2 diabetics. Kind of makes you wonder how they got into medical school at all. Since it is quite obvious that missing meals leads to weight gain, the old bogeyman, ‘starvation mode’ is often invoked to instill fear. Tales of people ‘ruining’ their metabolism abound. Food companies, of course have eagerly ‘educated’ medical professionals about the dangers of missing meals and the safety of eating sugar. Nobody makes money when you skip meals.KafkaFast

Fasting appeared in the medical literature over 1 century ago. Interestingly, they describe ‘professional fasters‘ who would fast for specific periods of time for exhibition. One professional faster went for 30 days and drank a quantity of his own urine. Talk about being starved for entertainment. Kind of like watching paint dry.  This was depicted in Franz Kafka’s short story “A Hunger Artist”. Fasting for entertainment was popular from 1883-1924. My guess is that it really is not that entertaining.

In the early 1900s, Drs. Folin and Denis described fasting as ‘a safe, harmless and effective method for reducing weight of those suffering from obesity’. Great. That’s exactly what we need. Something safe, harmless, and effective. The fact that fasting has been performed (mostly for religious purposes) for several thousand years only reinforced the long history of safety. It’s hard to argue that fasting is dangerous if people have been doing for the 5000 years. May as well argue that using soap is dangerous. Yet, myths about the dangers of fasting are everywhere.

By the early 1950’s, Dr. W. Bloom reignited interest in fasting as a therapeutic measure mostly using shorter fasting periods. However, many longer periods were also described in the literature. Dr. Gilliland reviewed fasting in the revival of the 1950’s and1960’s and reported his experience with 46 patients “whose reducing regime started with a standard absolute fast for 14 days”. Whoa. I love that. When I tell people to fast for more than 24 hours their eyes just about bug out of their head. These people had a ‘standard’ fast that lasted for 2 weeks! And that was just the beginning!

Of these, there were 14 males and 32 females. This is important because I constantly get questions about whether fasting works for females. This is primarily, I think due to a post found online that’s been viewed close to 100,000 times. What she wrote in 2012 is this – “Intermittent fasting and women: Should women fast? The few studies that exist point towards no.”

Nothing is further from the truth. There are hundreds of studies spanning over 100 years and clinical experience spanning 5000 years that point to the fact that women and men respond more or less equally except in the underweight situation. This is an easy problem. Should anybody who is seriously underweight, fast? Uh, no. You don’t have to be a genius to figure that out yourself. If you are severely underweight and fast, you could become infertile, yes.MenBigBabies

Consider the past 2000 years of human history. Are Muslim women ‘exempt’ from fasting? Are Buddhist women ‘exempt’ from fasting. Are Catholic women ‘exempt’ from fasting? So we have millions of person-years of practical experience with women and fasting. And there are no problems in 99.9% of cases. In our own clinic, where we’ve treated close to 1000 patients, I have noticed no significant difference between men and women. If anything, the women tend to do better. Men, it seems, are sometimes just big babies. I will mention here, too, that the highest success rates come when husband and wife do it together.

However, pregnant women are, in fact ‘exempt’ from fasting in almost all human religion. As are children. In both situations, this makes entirely logical sense. These people need adequate nutrients for growth, and human populations have always acknowledged this.

Let’s be clear here. This point is made that several problems come up with fasting in women. Well, they come up with men and fasting, too. Sometimes women don’t lose weight the way they want. Well, that happens with men, too. The problem of amenorrhea arises when body fat is too low. Yeah, that’s not a problem we treat with fasting. If amenorrhea or any other problems appear during fasting – stop immediately.  The women and fasting issue is just another myth designed to discourage fasting.  Virtually all case series of the past 100 years have included both men and women.Gilliland1

Anyway, back to the study. The patients were hospitalized into a metabolic ward during the first 14 days and only water, tea and coffee were allowed.  After that, they were discharged and asked to follow a 600-1000 calorie diet. Funny enough, 2 patients asked(!) to be readmitted for a second 14 day period of fasting because they wanted better results. Did it work? Was there ever any doubt?

Average weight loss was 17.2 pounds in 14 days. This is in excess of the roughly 1/2 pound per day of fat loss seen in more prolonged fasting. This indicates that some of the initial early weight loss is water weight. This is confirmed by the rapid regain of weight upon refeeding. It is important to understand this in order to avoid the disappointment that often accompanies the weight gain upon eating again. That quick weight loss and regain is water weight and not a reflection that the fasting ‘failed’. 44 of 46 patients completed the 2 week fasting period. One developed nausea and one simply decided against it and dropped out.

That’s a 96% success rate even for a regimen as long as a 2 week fast! This is our clinical experience as well. People always think they cannot do it without ever having tried it a single time. Once we start with fasting, patents in our Intensive Dietary Management (IDM) program quickly realize that it’s actually quite easy.

However, after the fasting period, patients were instructed to go on a low calorie diet. This was terribly unsuccessful. 50% of patients did not adhere to this diet over the ensuing 2 year follow up period. Instead of applying successful intermittent techniques, they returned to the unsuccessful constant energy restriction we discussed at the last post.

The key point here is that the natural rhythm of life is Feast and Fast. There are times that you should feast (weddings, celebrations), and there are times that you should fast. Intermittent. To constantly restrict calories for years on end is unnatural and ultimately worse, unsuccessful.Drenick1

Ketones appeared in the urine starting on day 2 and persisted throughout the fasting period. All 3 diabetic patients were all off insulin by the end of the 2 weeks. One patient with severe congestive heart failure was able to walk without breathlessness by the end. This 2 week fast was not harmful, as we have been told, but extremely beneficial.

Was it hard? In fact, Dr. Gilliland describes a ‘feeling of well being’ and ‘euphoria’. Hungry? Well, no. “We did not encounter complaints of hunger after the first day. We did not meet anorexia.” These experiences were echoed by other researchers of the time.

Dr. Drenick, from the VA centre in Los Angeles, also wrote extensively about therapeutic fasting. His experience was published in 1968. This was a time of renewal of interest in fasting for weight loss. He published his experience of 6 men and 4 women (yes, again there were women in the study). Did it work? In a word, yes.

Should women fast? Yes

Should men fast? Yes

Start here with Fasting part 1

Continue here for Fasting part 11

51 Responses

  1. You have a marvellous way of making the complex simple.

  2. Hello Dr. Fung. I am trying to follow aversion of your program without being your patient. Fasting no more than 72 hrs and every 24 hrs having a meal. I am having my doctor check my #’s for me every 3 months… My A1c was 6.2 so I want to stop this insanity before it’s to late. I enjoy reading your website here and watching your webinars. Keep up the good work. I am so interesting in this that I started my own fasting group called Fung Shweigh… Thank you again.

  3. Deb Griffith

    I love the name, Sandy! So cute! Is it a local group? I often think that we should develop local chapters for fasting.

    • Deb, I follow Dr Fung’s webinars and follow his rules for fasting. I use my own doctor for my blood test. I am on no meds at the time… You can find my support group on Fb .Im in Caif. We help you get thru your short fasting but no more than 72 hrs as you would need a docotrs for that ….we help each other and give support………..

  4. Bernard P.

    Dr. Fung, could you explain a bit further why initial weight loss is associated with water loss, as well as why weight gain upon refeeding is also associated with water weight gain?

    • Jennifer

      Bernard, it is quite simple, food (and especially carbs) bind water to your body (in the intestines, in the blood flow, in the muscles), I’d say between 1-3kg water, and when you fast there is nothing that can hold on to the water in your body so it is released out. Once you break the fast if you eat a lot the liquid you consume will get retained into your body again and you will gain the water weight again. It takes more effort for the body to bind fat, therefore it will take longer to gain weight in fat, and also it will take longer to loose the fat that has been stored in the body. Limiting carbs and do regular fasts will keep the water weight to a minimum and make you loose fat.

    • Look up muscle glycogen.
      When you eat (especially carbs) your liver and muscle glycogen stores are refilled. Glycogen is stored in hydrated form (three to four parts water).
      A person can store about 400g of glycogen, that’s 1 to 2 kg of water.

  5. Deb, I follow Dr Fung’s webinars and follow his rules for fasting. I use my own doctor for my blood test. I am on no meds at the time… You can find my support group on Fb .Im in Caif. We help you get thru your short fasting but no more than 72 hrs as you would need a docotrs for that ….we help each other and give support………..

  6. What the Fung! Another brilliant blog. So encouraging

  7. I did a three week fast when I was 17 years old. Supervised. Plenty of water. Occasionally thinned out juice if weakness became a problem. I lost 18 lbs in three weeks during the month of July. Re-entry was difficult but there was some teaching about what to eat and when. By november my hair fell out to the point of thinness and I saw a doctor who prescribed a B multivitamin, etc. I was able to keep the weight off for a bit but once regular eating was resumed it came on. Bottom line though is that fasting does work.

  8. […] Continue with Fasting part 10 […]

  9. Jennifer

    Thanks Dr Fung for addressing this myth! I must admit I got a little concerned after finding that article online, but I also thought that I’d give it a try and if I would notice any negative effects I would just stop.
    I have done IF for a bit over a month now and it is really interesting and fun to realise how easy it is to not eat for a few days, as well as my body set weight is going down. I wanted to loose my 5 last stubborn ‘comfy-kilos’ (I’m normal weight and healthy) and 2 of them are gone so I’ll continue until i reach my goal and then I’ll switch to a less agressive IF regime (currently doing one 48-65hr fast a week and 16:8 the rest of the days, mostly low carb diet but with a few exceptions). I am sure if I hadnt cheated with a couple of carb-loads and some desserts (and alcohol) following my fasts i would already have reached my goal, however I am cheating and STILL loosing weight. After the summer it will be easier to not cheat but rose wine, roasted potatoes and ice cream is hard to avoid during the summer! 🙂

  10. Jennifer

    Also, I would love to hear more stories from women, does anyone feel like sharing their regime (duration, how often, weight change, other benefits etc) and how it has worked out? Always fun to hear and good for the motivation! Thanks! 🙂

    • Jennifer, I a 57 year old female (menopausal). I am slightly overweight (10 pounds) after being obese and suffering from PCOS my entire adult life. I lost 70 pounds as of 4 years ago following LCHF and never had any trouble following the lifestyle which I continue to practice. About 4 months ago I started IF (14:10) and about 6 weeks ago I started fasting 24 hours once a week in addition. I feel great and all my metabolic markers are excellent. I have not lost any additional weight but I believe we are designed to gain weight in the summer to prepare us for the winter so the fact that I haven’t gained is a plus. I am sure that if I keep practicing IF, I will lose the final 10 pounds during the 3 fall months just in time for the winter feasts, LOL. However, I never gain weight during the holidays as I don’t like so called holiday foods.

  11. Deb Griffith

    Jennifer, I have been doing some version of IF since mid April. I started when I found out about 5:2, then quickly morphed into other versions. I now do 16:8 at least 5 days a week, or 19:5 when I need a boost. I am very low carb, as my body just can’t process them without putting them right into storage. So I am mostly all-meat (and yes, it is safe and proven). I do have 1 or 2 refeed days, and “cheat”, if you want to call it that! I do not count calories….ever.
    So, at 53 years old, menopausal over 10 years, and was stuck around 180 for the past 6 years, and after quitting the long hard hours at the gym, I now weigh 151.6. I have to keep revising my goals!

    I am on the Fast Diet forums. There are many , many similar success stories there also.

  12. Thanks for posting this Dr.Fung, I am trying to be my wife on board with fasting and there is alot of mixed opinions out there about women fasting and the potential dangerous side effects. My initial thought was that it would would work for her as it has worked for me but i didn’t want to put her health at risk after reading some other sites. I am glad to hear that she will be fine to give it a go. Thanks again for hitting the nail on the head. PS: I recommend anyone fasting watch the show Naked and Afraid on the Discovery channel, it illustrates what fasting probably looked like when we were hunter gatherers.

  13. I think it would be very interesting to have a FB page dedicated to Dr. Fung and fasting. I am part of a few IF groups but when I tried to post and shared about my extended fasts (96 hours per week, water only) – I was turned away as they thought my postings would be dangerous for their audience. I would love a place where I can only share – right now, I feel like I have to keep what I do a secret from my FB groups and have been told directly that as a diabetic it is dangerous for me to do such fasts.

    • great idea I also made my own to help other Fung fasters…. if you want to join its Fung Shweigh….

    • You’re also welcome to my Periodic Fasting group 🙂

    • I am also a diabetic and am using IF with excellent results. I am also an RN and have monitored patients while fasting. The danger of fasting if diabetic comes from taking medication because your blood sugar can drop too low, especially with insulin. I would not do this without someone following you closely if you are on meds. However, if you are on no medications, this is really IDEAL for diabetics, as you are both lowering your sugar and your weight; Watch this video ( https://www.youtube.com/watch?v=mAwgdX5VxGc) for a more in-depth explanation. The problem with type 2 diabetics is insulin resistance, and fasting can increase insulin sensitivity over time. HTH

      Dr. Jason Fung: Absolutely correct. In our clinic we reduce medications while fasting, but only under close medical supervision.

  14. Sonnenblume

    Fifth week on 16:8 during weekdays with a “bulletproof” coffee in the morning! Added this to my LCHF Lifestyle as I just was not feeling hungry in the mornings for any breakfast. My weight has not moved a gram since March (still need to lose some kg’s, I have blood pressure that did not react to the LCHF-change as expected), and I was hoping that this would give the needed kick. However so far nothing has happened in that respect, but otherwise I am feeling great.

    I was wondering if I should skip the bulletproof and drink regular coffee instead – but then my calorie intake per day will definitely not be enough for a woman of my size and with my activity Levels (180 cm, current weight 97 kg, physically active 4-5 times a week (Yoga, HIIT))… or at least that is what my gut is telling me 🙂 maybe I should try. Anyone here with similar experiences?

    • Hi Sonnenblume, When I tried 16:8 with bulletproof coffee for breakfast, I never lost weight. When I went back to regular coffee on the 16:8, weight loss was easier. As long as you eat until you are full and avoid carbs, the number of calories should not matter.

    • I originally tried bullet proof coffee for my “breakfast” for the days I fasted until lunch, but I found I did not need the bullet proof coffee at all (other than to increase fat content, if I want to do that). Now, I just have coffee and a small amount of cream. Since trying fasting until lunch with then subsequently without bullet proof coffee, I’ve since fasted until dinner (twice a week), then did one longer fast (missing one whole day) and one fasting until dinner per week, then started doing a longer fast every once in a while. I’m up to three days fasting for my “record”.

      Personally, I find fasting really works well, and is freeing. I no longer feel the need at all to eat breakfast, though I do. We just got back from a European trip, and the hotel had a great low carb spread, though I did eat a little bread too. So, I had three meals a day for three days. But, when traveling back, I did not eat for the 15+ hours of travel from Europe to the states. I also like that if I’m busy, I can miss a meal with no problems.

      Fasting also seems to have cleared my skin and provided other benefits, too, especially increased weight loss. I was losing slowly on a low carb diet, but fasting made that much faster.

      • Oops, I meant to say I do eat breakfast sometimes. However, it’s rare now for me to eat breakfast. I actually feel better if I do not eat breakfast after my workouts, but I’m only working out three days a week (two aerobics, one lifting weights).

    • Sonnenblume

      Sarah & BobM,

      thanks for your comments. I’ll skip the butter starting tomorrow. Lets see if that is the key to getting things moving again.

      I have noticed that my eating pattern has naturally adapted to having a meal twice a day. During the week it’s a late lunch at work (around 13h) and a dinner (between 19h and 20h). Weekends its more like a brunch between 10-11h and an evening meal. I cannot remember last time I felt really hungry. Sometimes I feel a bit peckish before lunch, especially if I did a workout in the morning, but it is not “real hunger” 🙂

      Maybe fasting could help my skin as well, I look like a Teenager ever since I started the LCHF Lifestyle and nothing seems to help.

      The most important thing is though, that I feel wonderful, sleep well, and did lose some weight initially as well (8 kg). I am happy with the way I look, but need to drop some more weight to get rid of the blood pressure medication. I cannot accept that I would have to take them for the rest of my (working) life.

      Will Keep you posted..

    • Sonnenblume

      A quick follow up:

      16:8 is great and I am still following that protocol for three days a week. I stopped drinking Bulletproof coffee. It did improve my general wellbeing, but did nothing for the weight loss. I had a regular bloodwork done in October, all was well, but my nr 1 “Nemesis”, my BP, hadn’t changed either.

      Since mid November, I added two 24hr fasting days to my weekly routine. This means fasting between sunday dinner and monday dinner, eating 16:8 on Tuesday and Wednesday, another dinner-to-dinner from Wed evening to Thu evening, followed by 16:8 on Friday. This is so easy and simple for an office worker like myself. Weekends I’ll eat whenever I am hungry, or whatever fits the rest of the schedule (social situations).

      After 4 weeks, BP is at 126/75 12hrs from taking my medication (it used to be at ca 140/85-90). I have lost 3 kg. My skin is still like a teenagers’ but frankly I don’t care if this will finally get the kilos moving and help my BP. I plan to continue this way now over the Holidays, and see how I feel after 3 months. I still have some weight to lose, I personally would be happy with another 6-7kg, whereas for a normal BMI ( and yes, I know that BMI is not a reliable Ratio) I would need to lose 12 kg.

  15. My weight has been “stuck” for a while and I decided to try a version of fasting to see if that shook anything up. I started out just eating all my meals in a 4-6 hour window, and fasting 18-20 hours daily. This proved very easy to do. I’ve now decided to move more to an alternate-day plan with only 400-500 calories on the low days.

    I rather enjoy the fasting. I’d heard the “rumors” about fasting not being good for women but could never quite understand why that should be so. I’m 63 and about 10 years post-menopausal.

    So far I’m feeling good, weight down about 12 pounds, and blood sugar dropping too.

  16. Debbie you’ve tried 3 versions of fasting, were any of them more effective weight-loss-wise out of them or was it just a matter of compliance or difficulty that’s the difference ?

  17. Jennifer

    Dr Fung, what is your opinion of the 5:2 diet where 500kcal is ok during the fasting day? Will it still provide most of the benefits (just a bit less effective) or does that count more as reduced calorie diet?

  18. Sonnenblume- no calories what so ever on a fast especially a BPC ..that’s your problem. Defeating the whole fast. Hope that helps

  19. Do you only recommend fasting for those trying to lose weight? I don’t want to lose weight because I am in this range where if I get under 125 lbs I experience amenorrhea. In the article you mention not eating more when you break a fast. I always do because if I didn’t, wouldn’t I naturally lose weight? I am T2D and have do a 24 hr fast 1x week, and 3x I do 16:8, and 3 days I eat first thing in the morning. I think the fasting has lowered my blood glucose so I like to do this, however if I don’t binge at times I am afraid of losing weight. Last time I had amenorrhea it took me 2 years to recover from it and I don’t want to go through that again.

  20. Dr. Jason,
    Thank you for your blog. It explains a lot of frustration that I have been facing in the past few years, just focussing on cutting carbs without considering the entire picture of Hormonal Obesity Theory.
    From my experience, I finally came to a conclusion similar to the BSW theory (though I didn’t know it was a thing).
    Also from your advice, vinegar has proved to be a great appetite regulator.

    Can you also shed some light on insulin resistance and its relation to PCOS? Would fasting be helpful in overall balancing of hormones (and thus weight-loss)? I fasted last Ramadan with ending my fasts with healthy fruits & soups and that immediately helped regularize my monthly cycle.
    What guidelines would be helpful specific to PCOS, other than the one’s already mentioned in your blog? Also my gynac said said that coffee will aid androgen growth, so is it better to stay away from it given the PCOS angle?


  21. Dr. Fung, Thanks for this series. I might mention that it was difficult to find the first one – I think a page where all your links and lectures are organized would get the word out there better. I had to do some serious searching to find several of your better articles and lectures. If you had a site map or better resource page it would be most helpful to those that are curious. I find that I get through my fasts better if I read or listen to some of this informative supporting work. I am at hour 60 of my first fast and am surprised at how easy it is past the first day. I might go past today – but had originally planned for just a 66 hr fast from dinner to lunch on day 3. My numbers have dropped significantly already – boosting motivation to continue. I am in your program with Megan. Excellent program. Thanks

  22. […] Concerned with fasting being detrimental, I continued to search and found this wonderful page…. […]

  23. Dr. Fung, Will fasting heal my broken bone in less time?
    Or should I opt for the high protein diet.
    Thank you

  24. Heidi Thorsen

    I tried the 5:2 diet combined with LCHF two years ago, and lost a lot of weight. But I found that it was so effective at reducing my appetite, that I was eating a 500 calorie salad on my fast days, and I was full eating just 700-900 calories on my “feast” days. I lost plenty of weight, but after several months I started to feel bad, and my hair was falling out and my skin and fingernails went bad. I was alarmed by this, and stopped the fasting and eventually regained all the weight.

    I’m back on LCHF now, and have lost some weight but plateaued, and I would like to get to a lower set point weight since I’m still rather overweight. My question is how should I incorporate fasting without it inadvertently turning into a permanently calorie-restricted diet due to loss of appetite? Should I just try for longer water/coffee fasts and not eat at all until I’m hungry, even if it takes many days? Will that take care of bumping up the calories when it’s time to eat again? I’ve tried the daily fasting from 7pm-noon sort of thing, but that just keeps me at the same weight, and my appetite is stable.

  25. Is it possible that weight gain after a fasting period is the body’s way of replenishing some fat stores in preparation for the next famine? Kind of the prehistoric version of saving some money (food) for a rainy day (famine).

  26. Dear Dr. Fung,

    Have you ever heard of the biologist, Dr. Ray Peat? Some of his theories on fasting have been circulating online, mostly about how fasting raises cortisol levels and is detrimental to our health over the long term. Out of curiosity I found his articles online and read a few on how to balance hormones. Some of his articles are kind of fascinating to read. He doesn’t think sugar causes diabetes, but unsat fats do –??

    I know you’re really busy right now, but was wondering if you had any comments about his ideas?

    Thank you for your time,
    kind regards,

  27. […] articles that explain IF for women very well, I recommend reading all three for further reading: 1, 2, […]

  28. My question is, by IF do women stop ovulating? I am torn between trying to cure some of my insulin resistance for the sake of getting to a more normal weight for pregnancy and possibly not being able to get pregnant once I get there.

    • Hi Olive,
      I still have regular periods, at age 50, doing anywhere from 16:8 to 20:4 every day. : )
      But if you are worried, you can always do a milder version, like 14:10 (3 meals, no snacks) and walk or workout in the morning before you eat anything, taking water only.
      Such a protocol worked great for me when I was a bit younger!!
      Getting Gestational Diabetes is NO FUN. Take care of yourself now, mama! <3

  29. In this podcast (https://bengreenfieldfitness.com/2017/03/366-float-tanks-strobe-goggles-hacking-vagus-nerve-natural-marathon-fueling-know-youre-recovered-adrenal-fatigue/) Ben Greenfield makes a point that kisspeptin is more suppressed in women who fast and can cause all sorts of hormonal issues for women in prolonged fasts. Any evidence you’ve seen of that?

    • Ive been fasting for six weeks now 16:8 doing exercise in fasted state, I was feeling great, until this last week I started to feel with very low energy and my period started earlier, 1 week sooner than usual. Thats why i ended in this blog trying to find some info for hormonal issues. I’m 35 years old.

  30. Great series of posts Dr Fung.
    I saw a graphs of a 7.7 year study of a low calorie diet. This graph sealed the fate of those diets for me. I now understand how fasting works for reducing weight. This is provided the fast is over 24 hours because there is no calorie intake for that day. Therefore, on other days, the calorie intake is greater than required for those days and lost on the fast days. In this way, there is no calorie restriction on eating days (no BMR reduction). On fast days, there are no calories and no BMR reduction. In time, the insulin resistance in improved and hopefully cured therefore, when the weight is reduced the body will not regain it.

    I don’t think I saw a graph of a study about this type of fasting weight loss over 7 years or so. If there is anyone out there who knows of such a study (and graph), it would be great to be able to refer to it.

  31. A weird thing happened to me, I am a woman in my 20s. After doing a four day fast, I noticed my chest size became significantly bigger, (and a little TMI, I felt them getting sore during my fast) kind of amazed at this effect. Don’t know if it’s associated with the growth hormones, I would love to see more studies exploring the various hormonal changes during fasting..

  32. I did such a ‘hospital water fast’ about 25 years ago. Hungry pangs, yes, regularly, but less and less frequently. I also needed to sleep occasionally in the middle of the day and at the beginning of week 2 I got cold to the bone but it all came and went. So far the unpleasantness.
    I went into hospital with my hormones in a mess. On discharge, I was told that due to pills I was on before, they never knew what the problem was and that I was now clean as a whistle. I felt absolutely WONDERFUL. On top of the world. Strange enough, upon re-feed, I couldn’t eat more than 1/8ths of a steamed trout. Go tell. So hunger wasn’t really ‘hunger’, since I couldn’t eat….

    Now, question : What do we need medical supervision for in case of fasts of more than 3 days if nothing is wrong with us apart from weight ? Is working in fasted state recommended or should I wait till I’m on leave ?

    dr. Fung : thanks for saving my health and ultimately, my life. Never underestimate what you’re doing…

  33. “The problem of amenorrhea arises when body fat is too low.”

    That’s incorrect and a gross over-simplification. It can arise in very lean individuals, but for most women it’s far more complex. The problem with functional HA is thought more to relate to an energy deficit and is also closely linked to stress. So, if fasting seems stressful and you’re in a deficit, with a hypothalamus that is sensitive…then you get amenorrhoea. To be so flippant about it is worrying, quite frankly, and shows a lack of knowledge. You claim great health benefits from fasting etc, but amenorrhoea comes with the risk of osteoporosis and endothelial dysfunction. It’s hardly a nothing.

    • I’m 27, and have been eating 70-80% paleo for the last three years and went from ~172 lbs down to ~158. About four months ago I started doing IF, and go 14-18 hours daily without eating, and I have no problem with it as far as feeling tired or hungry. I break the fast whenever I start feeling hungry in the afternoon. I usually eat around 1,500 calories a day, (sometimes 1300, other days 2300) and get plenty of fats, usually about 60-70% of my caloric intake. I’m at 147 pounds (still about 15 pounds overweight) and I have had problems with my cycle the last 3 months. It started out as being a few days longer than normal (it was always 29 days exactly) with some spotting. This month I’ve completely failed to begin my period (not pregnant). I have tried to induce bleeding with large amounts of vitamin C (I’ve researched this) and have only gotten very minimal spotting. I’m upset because I enjoy this lifestyle and reap benefits but I want my normal cycle back. I plan on having children in the future. Anyone with input please respond.

      • Dani – have you checked out Leanne Vogel at Healthful Pursuits? She did keto to beat her amenorrhea. You might need to change up the type of food you eat during your feeding periods to ensure you are getting the proper nutrients. That may include carb ups (again high nutrient dense carbohydrates).

        I’ve been fasting for the same period and started the same weight as you and while my periods are slightly wonky (just in their length), they are still regular but now I am really focusing my effort in quality of foods when I eat. Definitely check out Leanne Vogel and you might need a slight break from your disciplined fasting for a bit.

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