October 26, 2016

Not So ... Fast ... (Part 2)

In part 1 of this rant, I got a little hot-headed about having to explain to people who should not be fasting that fasting is not appropriate for everyone. In this follow-up and continuation, I’d like to say a couple more things because these ideas have been nagging at the back of my mind, and they won’t go away unless I get them out. I don’t think anyone will learn anything from this one, and that’s okay. I rarely use my blog as a plain ol’ brain dump with no educational tidbits whatsoever, but I suppose I’m entitled to that once in a while.

Before I start, let’s clarify something:  if you feel good doing what you’re doing with regard to diet, exercise, fasting, and sleep, then keep doing it. But if you don’t feel good, there might be reasons why you don’t feel good. And my intention in writing about some of them (aside from letting off steam, because this is all starting to really get to me) is to bring attention to the mere possibility—just the chance—that any of this might make sense. Please know that this is wildly speculative. I’m thinking out loud. That’s all. My blog isn’t a doctoral thesis I’m required to stand up and defend against a panel of experts geared up to prove me wrong. It’s just my thoughts and opinions, which, as always, you are welcome to read and ponder, or completely ignore. You can even disagree with me; I ask only that you do so in a civilized, polite way to facilitate discourse like the intelligent adults we are. :-)


Last time, I made a point to explain how much I respect Dr. Jason Fung, and how much I agree that fasting can be a wonderful help for many people, when it is engaged in rationally and intelligently. So I need not rehash that here. Let’s cut to the issues.

When defending himself against his critics, Dr. Fung talks about how people have been fasting for thousands of years for religious or cultural reasons. Yes, they have. But context matters. They were not fasting and also under-sleeping (with totally screwed up circadian patterns thanks to brightly lit electronic gadgets and gizmos), already chronically undereating (particularly in the context of frequent bouts of intense exercise), or psychologically stressed out all the time. Looking at things through that “evolutionary lens” we’re all so fond of, the stressors our hominid ancestors (likely) dealt with were acute but short-lived. Being chased by a large-fanged, sharp-clawed predator is definitely a terror-inducing and pants-wetting stressor, but it probably didn’t occur all day every day. Not even for half a day, or for the length of, say, an 8 or 10-hour work day.

The stressors of ancient times—or so we hypothesize—were intermittent, unpredictable, and probably short-lived: a predator in the camp, conflict with a neighboring tribe. Members of the early Homo genus—and even modern, full-blown Homo sapiens, up until very, very recently—weren’t worried about whether their kid was going to get into that exclusive, snooty preschool they’ve been on the waiting list for since before they were even conceived. They weren’t worried about getting a big project done by the deadline imposed by the terrible, incompetent, mean, oaf of a boss they work for. And they sure as crap weren’t worried about losing fifteen pounds because “bathing suit season” was coming up, and the hot single Grok who lives two caves away might be disgusted if he sees Grokette’s stretch marks or jiggly thighs.

Did cavepeople, medieval people, pre-Columbian people, Renaissance people, hominid ancestors-to-people, and all other “people” face stressors? Yes. They surely did. But going without food for a while for them was—maybe—a bit different from people doing it today. 

Fasting for Ramadan, or Yom Kippur, or Lent, a thousand years ago was (probably) a totally different story from fasting and working at a job you hate for 60+ hours a week, and sitting in rush hour traffic twice a day, and doing fitness boot camps, and worrying about your credit card debt, and having an existential crisis, and raising kids—particularly when you don’t have a lot of outside help. Did our ancestors have to look after their young ones? Yes, of course. But back then, the whole damn tribe probably pitched in. It wasn’t every mother or father for him or herself. It was a team effort, in the way childrearing typically is not these days. No longer do we live in small bands or villages where people benefit from the help of multiple generations, close friends, and not-so-close friends: aunts, uncles, grandparents, other people in the tribe. Grandma, grandpa, and Uncle Bob weren’t some afterthought who get cards at Christmas and maybe on their birthday if someone happens to remember. They were constant presences, there and ready to pitch in.

But I’m getting off track. Back to the matter at hand. Did ancient and not-so-ancient people face difficulties? Yes. Some were enslaved to harsh taskmasters. (You think you hate your boss?) Some probably had to scrounge for food now and then. Some went to war. Some cut themselves on rocks or twigs and died from infections we can now cure in a matter of days. Even so—and again, I am just thinking out loud, running through some possibilities—it seems to me that overall, their total load of physical and psychological “stress” was not as unrelenting as some people’s in good ol’ 2016. (Much of it self-imposed, yes, but it’s there nonetheless.) I would speculate that even the “stressors” of life in, say the 1700s, weren’t as constant and unrelenting as the ones we face today. And yes, average life expectancy was much lower back then, and we could use this to argue that mimicking the lifestyles of the past might not be such a great goal. (Plus, as a woman, I kind of like having the right to do cool stuff, such as vote and own property.) There are lots of other reasons why we falsely over-romanticize the past. But sticking to the matter at hand, the lower life expectancy way back when was mostly due to infectious disease and far greater infant mortality. It wasn’t because life was necessarily inherently more challenging or “stressful.” People who fasted hundreds or thousands of years ago did so in a context of life that (I am speculating) wasn’t the constant, daily, nonstop sensory assault we face today: bright lights, traffic, noise, pollution, worries over grades, or job performance, or where you’ll get the money to fix that funny noise the car is making, or running for two hours to pay penance for the donut you ate this afternoon, and the self-imposed agita over the forty-one unanswered emails in your inbox and the sixty-seven Facebook comments you haven’t had time to reply to or even “like” yet.   

What I’m trying to say is: When you’re already under a lot of stress, why add fasting to that mix?

And again, I must stress, if you fast and feel great, then keep fasting! I’m simply speculating as to why some people don’t feel great when fasting. Truthfully, once someone becomes accustomed to fasting, I think it can actually help people deal with the craziness of life nowadays, but that is neither here nor there. I’m not saying the pace of modern life is a reason not to fast. Like I just said, some people actually handle things better when they fast. I’m only saying that if you don’t handle things better, and you don’t feel like a rock star when you fast, it’s not a huge surprise to me.

Last time, I talked about fasting as maybe a not-so-great idea for people whose habitual diet is already a severe caloric deficit, who exercise intensely and frequently, and who lack the psychological fortitude—or basic knowledge of human physiology—to refuel properly. I speculated that the difference between men and women who fast and work out too much a lot is that however long men fast and however hard they work out, when it comes time to put some fuel back in the tank, they will E-A-T. In contrast, women will have what they normally have—which is not enough food. Whether it’s low carb food, high carb food, Paleo food, vegetarian food—it is Not. Enough. Food.

I’m no Loren Coradin or Boyd Eaton (sort of the grandfathers of the Paleo movement, for those of you who've never heard of them), but I would imagine that back during the Paleolithic era, our ancestors weren’t absolutely terrible hunters. Sure, they probably missed a kill here and there and either went hungry or subsisted solely on gathered plant foods for a few days. But they wouldn’t have failed all the time. They were probably pretty good hunters, actually. Some anthropologists believe they were so good, in fact, that what led to the extinction of some of the larger terrestrial mammals, especially in North America, was not climate change, but over-hunting! Yes, it may be that our ancestors were such good hunters that they managed to take down ALL of those gigantic and MEATY beasts. Is this true? I don’t know. I’m just pointing out that it’s a hypothesis (albeit a very controversial one, and no doubt climate change was a factor, regardless)—and that people way more informed than I am seem to believe maybe we didn’t go hungry all that often.

So I’m thinking that after what might have been some serious exertion—tracking and stalking prey, killing it, and then taking it back to the cave, campsite, or whatever—they would have EATEN! More often than not, a great deal of physical exertion was probably followed by some feasting. It wouldn’t have been exertion after exertion after exertion with very little to show for it. Here and there, for short periods of time? Yeah, probably. No doubt we would have had some unsuccessful hunting excursions. But not day after day, week after week, month after month. Running and running, throwing rocks, brandishing primitive-type weapons: at some point, it would have paid off and food would have been consumed with gusto. They wouldn’t have worked that hard every day and not replenished their energy stores somewhat frequently. This is (in my reasoning) why the reports of “fasting fails” tend to come from young women who work out a ton and already chronically under-eat. (Some are even underweight, to boot.) They’re starting from a metabolically precarious place. Add fasting on top of that and it surprises people that it doesn’t work so well?

Now, I’d like to reiterate that fasting—at least in my personal experience—can make some of those everyday, ceaseless life stressors easier to deal with. Even people who follow sensible low carb or ketogenic diets can fall victim to the blood sugar or free fatty acid rollercoasters, such that we might have an occasional incidence of “hanger.” And we can still find our mood and cognition doing wacky things from time to time, even when we’re eating well. Fasting—at least for some people—evens this out. It can make all of life’s … well, crap … easier to handle. And like Dr. Fung says, fasting makes a lot of things easier. Because it’s not something you do; it’s something you don’t do. (Eat.) No food to prepare, no dishes to wash, no meal to make time for. It frees up time and headspace for other things.

I’m playing around a little more with fasting, myself, and I’m finding that I much prefer doing a full 24 or 48-hour fast once in a while (once in a while!) over something like a 16:8 intermittent fasting regimen. I just find it hard sometimes to eat only during a pre-set time window. For me, personally, it has always been easier to eat nothing than it is to eat just a little bit of something. I might feel hungry—sometimes maybe even an intense, gnawing type of hunger—but eventually it passes. And for whatever reason, that hunger is easier to ignore or make peace with—and even enjoy, oddly—than trying to stop myself from eating more because “time’s up,” even though I’m still hungry or am craving something.  

Wow. This post was totally rambling. I guess I just felt like I had more to say than I covered in the main post.

Coming up on the blog in the next few weeks: a lesson on gluconeogenesis, and setting the record straight on why people really (really!) need to stop being afraid of protein. After that, I’ve got a semi-epic rant—and I do mean RANT—about perfectly healthy people following super-strict medically therapeutic diets just ‘cuz. Hopefully once that’s done, all of this frustration will be out of my system and I’ll get back to writing about things that might actually help someone.)

P.S. There are most definitely some physiological benefits to exerting oneself in a fasted state. Or not exerting oneself in a fasted self. There are benefits to exerting oneself, benefits to fasting, and benefits to doing them together. (You’ve gotta love a paper called “Neuroprotective signaling and the aging brain: take away my food and let me run.”) But eventually, at some point, you do have to eat. You have to replenish nutrient stores, protein, fatty acids, and other good stuff that build you up enough so that you can fast again and exert yourself again. I think what we have in the young women who do poorly with fasting is fasting and exertion, followed by fasting and exertion, followed by fasting and exertion. Maybe there’s a protein shake in there somewhere, or a spinach salad with a few bits of crumbled bacon because they think they’re on a low carb, high fat diet. But they’re actually on a low everything diet. Combine that with frequent bouts of high intensity exercise and we have exactly the “horror stories” we read about on the interwebz.

Bottom line: fasting isn’t harmful. Fasting stupidly is harmful.

Disclaimer: Amy Berger, MS, CNS, NTP, is not a physician and Tuit Nutrition, LLC, is not a medical practice. The information contained on this site is not intended to diagnose, treat, cure, or prevent any medical condition and is not to be used as a substitute for the care and guidance of a physician. Links in this post and all others may direct you to amazon.com, where I will receive a small amount of the purchase price of any items you buy through my affiliate links.


  1. All good and interesting thoughts as usual. Please keep sharing your ideas and perspective.

  2. I've never deliberately fasted - but I find that my body does it for me.

    When I was dutifully eating my high carb low fat diet (for decades) I would need to carb up every 2-3 hours or I would crash both physically and mentally.

    For over a decade now I've been eating low carb/Paleo, and this has literally been the first time I discovered the qualitative as well as quantitative difference between genuine hunger and carb cravings from reactive hypoglycemia.

    Now I routinely eat something like a buttered oatcake with smoked salmon or ham, and sometimes nuts or salad, for breakfast - just to stop my liver dumping too much glucose - then don't eat again until any time between late afternoon and late evening, depending purely on when I get hungry. Often I only have one main meal, and a snack similar to breakfast later, sometimes I have two smaller meals depending. I seldom snack because I no longer need to. Finally I can trust my body to signal what it needs.

    1. Good post! You found what works for you. I personally found that fasting 23hrs/day/(eating 1x/day)/5days/wk works wonders for me while eating a non-processed Lo-CHO HPHF diet when I do eat.

      Is it stressful? I don't think so. It might be when 1st starting out and getting your body used to it, but in a week or so your body and hunger adapts. I wouldn't recommend it to a diabetic, of course. But for anyone else that's having issues with their weight/health and not under a lot of external stress in their lives I would recommend it HIGHLY.

      In the end.... folks should experiment and find out what works best for them!

  3. I'm glad you mentioned that traditional hunter gatherers and Paleo people most likely didn't go hungry as often as "we" seem to think. I've always believed this- (and Gary Taubes writes about this in "Good Calories, Bad Calories"). Nowadays, most of us don't know how to hunt- (or if we do, we're probably not experts at it); so partly for this reason, I think we tend to assume that hunting was difficult, and food hard to come by. In addition, in today's world, animals are encroached by civilization and don't run freely all over the land like they used to. To me it makes sense that in a world full of wild animals, there was probably plenty to eat. Even in the absence of big game, there were plenty of insects, reptiles, turtles, birds, rodents, and everything in between. Native people ate pretty much everything that moved; they weren't limited to the same 3 animals that we tend to eat today! In addition to that, hunting and gathering were these peoples' full time jobs....why wouldn't they be experts at it? They had the same brain as we do, they just used it for different purposes, and had different knowledge. I suspect life wasn't as "nasty, brutish and short" as some people seem to think. Nowadays things are different of course, as the few remaining hunter gatherers that are left have been shoved onto less than ideal land....or there are restrictions placed on how much they can hunt. So we can't make assumptions about the past based on our current world.

    Actually, I've read that the advent of agriculture was really the beginning of food insecurity, famines, etc.

    Well personally, most of the times that I've fasted I've done well with it; however, I notice that after fasting, my appetite usually goes up and I tend to eat more to compensate (i.e. "feast"), which I always felt was fine; that's the wisdom of my body speaking!

    1. Totally agree. The difference now is the longevity folks, and I do think there's an angle there -- if your main goal is to live very *long,* there might be something to severe caloric restriction and/or fasting. There's a tradeoff between being reproductively fit and carrying a lot of muscle mass versus living a long time. Ron Rosedale covers it very well. (In these videos: https://www.youtube.com/watch?v=LvTE--5w808 and https://www.youtube.com/watch?v=Yv-M-5-s9B0) And I agree that the "nasty, brutish, and short" thing is overplayed, but I also think very few cavemen lived to 95... even if they managed not to get some sort of infectious disease or die during childbirth or during adolescence, I think it was probably not the evolutionary norm for people to live to 75-100. I think that's probably pretty novel, but also, our hominid ancestors weren't *looking* to live as long as we are now. So I think there really *could* be something to the protein restriction angle (and even total calorie restriction angle), but it comes down to goals/priorities: do you want to feel and look good and have lots of energy and good moods during whatever time you might have on this big rock, or do you want to limit your food intake in ways that might -- *might* -- help you live a few more years? (And it's not like you'll be living longer when you're in the shape you were in at 25...you'll be living longer in, say, your 80s...) Lots of unanswered questions, and I tend to not be all that keen on the protein restriction.

      But overall, I agree with you -- and some of the most popular and more importantly, most *knowledgeable* people in the low-carb research community actually really don't encourage fasting and in fact actively try to distance themselves from others who are proponents. (I'd rather not name names, but they're biggies.) It's funny, the schisms that happen behind the scenes that so few of us know about because puts on a united front in terms of what we *do* agree on. ;-)

    2. I am looking forward to your post on protein. Many people are pushing low protein now. Mercola follows Rosedale, Dr Hyman says meat should be a condiment and Dr Fung believes we eat too much protein. Dr Perlmutter too seems to be on the lower protein band wagon lately too. I don't know what to make of it all. I would look forward to your assessment.

    3. I am also looking forward to the post on protein. Yes, a lot of people may be pushing low protein at the moment, but I notice what happens is that one person says something on the internet, and suddenly loads of other people just start repeating it, and so it becomes a fad. To be honest, I'm skeptical of protein restriction. In her book, Nina Teicholz mentions that there were a lot of centenarians among the Sioux Indians back when they ate their traditional diet (of meat and fat. I'm sure buffalo meat is not exactly a low protein food!) It seems like people are just becoming afraid to eat nowadays, everything is "bad". Man cannot live by butter and coconut oil alone, which seems to be what some of these people are pushing....

      To my knowledge, there is absolutely no scientific proof that protein restriction and/or caloric restriction prolongs life in humans; this is only conjecture- (although it does seem to work with some animals; in apes, however, results have been inconclusive). My personal reason for fasting was partly because I was intrigued by the fact that it supposedly lowers insulin, and partly because I had read an article written by Dr. Thomas Seyfried, where he recommends fasting to prevent cancer. But if there are people in the low carb community who disagree with fasting, I would be curious to know, and what their reasons are! (Amy, can't you give us a little hint???) It would be interesting to hear another side of the story; maybe I would even rethink fasting if there is a good reason not to.

    4. Apropos cavemen and longevity: there are many things to say about this. Aside from the reasons you gave, and that they did not have medical care; there is also the idea that in a world full of wild animals ready to be eaten, some of those wild animals ate us as well! Since this so rarely happens in our world, it's another thing we often forget. In nature, you eat, and get eaten.

      Also, I wonder if longer life is a process of our evolution. People who study gut flora say that we've "evolved" to live in synergy with our microbes, and that they help keep us healthy. But maybe this has been an ongoing process; maybe in earlier days, this process had only just begun? And now we're benefiting from years of adaptation?

      Of course, on the other side, some people have suggested that carbon dating may not be as accurate as we think, so we may even be wrong about the ages of death. I'm not even sure that we've found enough skeletons from a single time period to really even know what the "average" life span was(?)

    5. My new favorite video on protein, from my #1 go-to guy on protein (just ignore what he says about low fat toward the very end; the rest is golden). https://www.youtube.com/watch?v=4KlLmxPDTuQ

    6. I had a look at that link awhile ago, but had no time to comment until now. (Thanks by the way, it was interesting). Wow, he says a high carb diet makes exercise ineffective! (Or something along those lines). And I did "ignore" the part about low fat. Why anyone would want to eat low fat dairy products when you can eat the delicious full-fat stuff is beyond me......

  4. I think your assumption that our ancestors were 'less stressed out", which I think is the crux of the entire article, is complete opinion and utterly baseless in fact, which makes your entire article really not compelling. I think the threat of starving, and the obvious higher/earlier mortality rate would lend them to be at least, if not more chronically stressed.

    1. Yes. Total speculation on my part, as I tried to make clear right at the beginning.

  5. I kind of think that we were designed to survive starvation. Peak predators lions are successful in one out of three hunts. Humans despite our ego weren't peak predators for most of evolution so I can imagine we lost many fresh kills to apex predators. I think the hormonal profile elicited by fasting hints to mechanisms that tweaked us to be more successful for the hunt.

  6. I firmly believe doing something like the common 16 hour fast followed by an 8 hour eating window is what works optimally for the culture we live in today.

    When Jimmy Moore did that 21 day fast recently, I thought that was a little crazy. I couldn't ever picture not eating for 21 days, it just wouldn't be fun.

    Anyways I definitely agree with you, fasting "stupidly" is becoming commonplace.

  7. Right on. Many, many women are already struggling with eating disorders, too much stress, too many things to do, too much meaninglessness in the hours they're already depriving themselves. I feel pretty great when I go without eating for a while, every once in a while. But Commando or Warrior or whatever they call it makes me not just feel sick but sad. Really sad. I would do a long fast for other reasons--"religious" reasons--but not because I'm 30 pounds overweight. Love me, love my extra 30 pounds. I'm working on. (BTW, I also think Dr. Fung's books are brilliant, but I really hate his tendency to mock people who don't "get it." Different styles. Thanks. This really helped a ton! (Heh.)

  8. Insightful stuff.. Amy thanks for sharing.