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

Is Intermittent Fasting Healthy?

If only I weren't so skinny!

One thing is certain in the field of health: what is common wisdom today can easily become “misapplied science” tomorrow. What’s “in” this year may be “out” next year. Often it’s hard to arrive at the right answer.

For example: Oily fish is good for you because the Omega-3’s are so healthy, but oily fish is bad because it can be contaminated with heavy metals, but oily fish is good because recent tests prove it’s not actually very contaminated, but oily fish is bad because the fishing industry paid for those tests…you get my point.

The Fats vs. Carbs argument is another. So when a reader recently asked about regular fasting as a means of maintaining good health, I had to re-evaluate my point of view slightly. What I found surprised me and convinced me to add a new twist to my ongoing health-and-anti-aging regimen. It’s called Intermittent Fasting – or IF.

Twenty years ago, as I was first forming my Primal Health point-of-view (based on a model of how humans evolved), I found it very easy to embrace the concept of “grazing” that seemed to represent the collective conscious of the weight-loss-and-health movement at the time. After all, eating several small meals a day – grazing to maintain even blood sugar and to avoid having your body go into starvation mode and start hoarding gobs of fat – seemed to fit my picture of early humans roaming the plains of Africa foraging for roots, shoots, nuts, berries, grubs and the occasional road-kill leftover from a hyena feast. The explanation that we in the weight-loss business gave the public was that by maintaining this steady supply of protein, fats and carbs throughout the day we would never experience a wild swing in blood sugar due to rapid rises and falls in insulin, therefore we would be less inclined to store fat and more inclined to burn off our existing fat stores. Heaven help us if we skipped breakfast, overate or starved ourselves periodically. That would surely wreak havoc on the delicate hormonal systems keeping us in homeostatic balance.

Well, maybe not.

The truth is, many people have succeeded in losing weight and keeping most of it off using this simple grazing method, which consists of eating 5 or 6 small meals or snacks spread evenly throughout the day, with no single meal exceeding 600 calories and where each meal or snack contains a little protein. This grazing method is the ultimate in portion control: take the 2400 (or more) calories you might otherwise scarf down in 2 meals and simply spread them evenly throughout the day. I think it’s reasonable to project that many more have avoided or postponed getting type 2 diabetes using the same method.

But like many behaviors in the fitness and health world, there comes a point where the benefits decrease and we find ourselves on the dreaded plateau.

The first thing most people will tell you about their attempts at grazing is, while it usually works well if you are diligent, it’s pretty difficult to stick with, since you need to be near a source of quality food every few hours. If you work at home most days as I do, it’s not a problem, but it can make life difficult if you work in an office setting or happen to be a road warrior.

The next common issue is that after a few months of progress, you arrive at a frustrating point where the weight stops coming off, the initial high energy levels decline or you stop building muscle. That makes sense from an evolutionary perspective, since the body is so well-tuned to adapt to any situation – including a perfectly even flow of nutrients. In this case, the body’s reaction to this steady supply of nutrition is to actually decrease insulin sensitivity. It “knows” there will always be food, so it “down-regulates” insulin receptors, and probably down-regulates other metabolic systems as well.

In my Primal Health articles here at MDA, I am always looking at ways we can harness our DNA blueprint to maximize health. I like to see how we can shake things up a little and trick the body into burning more fuel, creating more lean muscle, repairing cell damage and staying injury- and illness-free. So when my 79-year-old buddy Sid at the gym started raving about his weekly 24-hour fast over a year ago, and my friend Art started writing about his own fasting experiences, I decided to look into it further.

The results were surprising and impressive.

Numerous animal and human studies done over the past 15 years suggest that periodic fasting can have dramatic results not only in areas of weight (fat) loss, but in overall health and longevity as well. A recent article in the American Journal of Clinical Nutrition gives a great overview of these benefits which include decreases in blood pressure, reduction in oxidative damage to lipids, protein and DNA, improvement in insulin sensitivity and glucose uptake, as well as decreases in fat mass.

How can you argue with results like these? And it all makes sense from an evolutionary perspective, because our predecessors almost certainly went through regular cycles where food was either abundant or very scarce. The body may have established protective mechanisms to adapt to these conditions by sensitizing insulin receptors when it was critical that every bit of food be efficiently used or stored (as in famine), or by desensitizing them when there was a surplus, so the body wouldn’t be overly-burdened by grossly excessive calorie intake.

Beyond insulin sensitivity, it appears that caloric restriction and intermittent fasting may “turn on” certain genes that repair specific tissues that would not otherwise be repaired in times of surplus. One could surmise that this adaptation serves to allow certain cells to live longer (as repaired cells) during famine since it’s energetically less expensive to repair a cell than to divide and create a new one. That might help explain some of the extended longevity seen in animal studies using caloric restriction and/or intermittent fasting (read about here, here, and here). Intermittent fasting has also been shown to reduce spontaneous cancers in animal studies, which could be due to a decrease in oxidative damage or an increase in immune response.

So, what are the practical applications of this research?

It depends. There’s probably no right answer (remember what I said at the beginning!) Art suggests mimicking the experiences of our ancestors, which is to say don’t plan any fast, just surprise your body every once in a while with 24 hours of little or no food. My friend Sid does his fast every Tuesday like clockwork, so he has a light final meal on Monday night and doesn’t eat again until Wednesday breakfast. He does drink water and a little juice on his fasting day. Some fasting programs suggest you take a two-week “cleansing” approach where you eat regularly every other day and fast (or eat 40% of normal) on alternate days for two weeks twice a year.

One thing that is most interesting about the intermittent fasting studies is that slightly overeating on the non-fasting days (to make up for the lack of calories on fast days) yielded similar results, so it wasn’t so much about total calories as it was about the episodic deprivation.

As for me, I’m going to try the once a week deal, but I’ll start by no longer agonizing over a skipped breakfast or late dinner. What I used to think was the end of the world might just be the beginning of a new one!

Let me know of your own fasting experiences.

UPDATE: See this post on Women and Intermittent Fasting.

Further Reading:

My Carb Pyramid

Healthy Recipes

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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. There’s an excellent recent article by Steve Hendricks in Harper’s regarding fasting ‘your way to vigor':

    “Starving your way to vigor: The benefits of an empty stomach”

    patrick wrote on May 15th, 2012
  2. I am currently fasting from 7pm – around 2pm the next day. I train normally at about 11am or 12pm. I will take free form amino acids pre and post workout. My energy has been increased and I am sleeping better. I am going to start juggling my fasts with no structure. Some days I may go 16 hours, others days 24hrs and then other days not at all and eat as much as I want. I think shocking your body through different eating volumes and frequencies is just as important as mixing up your training regime for improved results. Thanks for the post.

    Matt Whitmore wrote on May 22nd, 2012
  3. I’m the kind of person that likes to have my cake and eat it too…and apparently the cake has been winning because I have not dropped my baby weight and my youngest is 6 :). I don’t remember how I came upon the routine I’ve been using for the past few months, but I’ve been averaging about a 1 lb. weight loss every week since I started.

    I like the idea of cutting out processed foods, but I also have a tendency to drool over things that I know are not good for me. So, this is what I do.

    Weigh-ins are reserved for Friday mornings (mainly because I know what I’ll be doing Friday, Saturday and Sunday; which would make a Monday morning weigh-in just dumb). You know the saying, ‘the diet starts Monday’! Starting Monday morning through Wednesday supper I eat Paleo, minus a chocolate craving here and there. Then I fast until breakfast on Friday, with the exception of my morning coffee. Some things just can not be interrupted.

    I find that my energy consistently increases throughout the week, and then I get the good news of the weigh in on Friday and I feel great going into the weekend. I eat and drink to my hearts content all weekend until I’m literally saturated and looking forward to Monday morning when I can stop the madness and begin to clear out all my ‘food and beverage sins’ once more.

    This may sound like a massive roller coaster, but I’ve found that it is the true key to my nourishment happiness AND I am finally getting rid of my baby fat. I LOVE IT!

    I’ll end it here, since there really isn’t anything going on in the way of an exercise program. I’m assuming I will get there and will finally get to one day parade around in a bikini again, but for now I’m enjoying the fact that my joints no longer hurt and I am regaining mental clarity and guilt free eating!

    I didn’t even know it was called ‘intermittent fasting’ until I realized I was on to something and decided to search the internet.

    Happy Fasting! (and eating).

    Vanna wrote on May 26th, 2012
  4. Ah, fasting. What can I say? When I first started it, I was a bit wary. Sure, I had heard all the industry tag-lines and “Sacred screed,” so to speak, and was giving it a second thought. But one day, out of necessity, I didn’t eat for over 36 hours—and let me tell you, after a life of cheeseburgers, shakes, fries, and all the other good American fare, feeling over-fed all the time and wondering why I was so tired, basically living a totally self-indulgent non-life, the 36 hrs I did weren’t so hard, and at the end of them, I actually felt….well, great! I had some energy, actually slept better than I had in a while, and so forth. Intrigued, I started to do some internet studies on giving up food, since I just felt so fantastic after not eating or a day. And I was happy to see there was some research and experiencce based info out there–so, I can now say, with certainty, after trying to be pretty regular at intermittent fasting, I find that I do not miss the food a bit, and feel really great on days when I do eat. Maybe I will get to where I am eating once every two days, instead. Definitely worth a try if you’re sick and tired of being sick and tired. Thank you for reading.

    Marv wrote on June 3rd, 2012
  5. In memoriam, Master Kwai Chang Caine
    died June 3, 2009
    Follow the endless highway, and find the Pacific coast…touch its water…and be free…..
    Marv, DHAF

    Marv wrote on June 3rd, 2012
  6. Hi Brad;This isnt really about this post but I weantd to ask you some questions. I have just discovered Intermittent Fasting/Eat Stop Eat and have downloaded your Elimination Exercise thing but weantd some advice on what Compound Exercises are best?? Im not a fitness expert so can get a little confused about what everything means!! In your PDF, you didnt mention anything about compound Abs exercises, unless the abs are dealt with in one of the exercises you mention. Anwyay, some hints as to what compound exercises would work everything including Abs that would be great! (in lay man’s terms too if you can !)ThanksLou

    Sreejith wrote on June 7th, 2012
  7. There are SO many “specialists” and theories out there as to what is best for us and I believe this is just one of many, too many, and it flies in the face of what we have been taught which is that going without eating for a prolonged period of time will slow the metabolism, one the main causes of obesity. For me, my sleep deprivation is kicking my ass and ruining my health and attempts at losing more weight. This plateau is frustrating me cause more stress which causes more cortisol which causes more belly fat, and so on and so on…:-(

    Sally wrote on June 20th, 2012
  8. 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.

    Dawn wrote on September 9th, 2012
  9. From me, I have been doing IF for 5 years. I am 55 now. Firstly, I must remind you that IF is something new to your body, it needs time to adapt. IF is a sudden change and your body will protest this torture. When I began IF, I did it gradually.I began by eating breakfast gradually later in the day. So if I ate breakfast at 6:00 AM for a few days, then I increased that to 8:00 or 9:00. Then I went to 11:00. It was exciting to go to noon without thinking about eating. Eventually I was able to go to 3:00 P.M. before having my first meal of the day. Now, I break my fast anytime after 3:00. I honestly try to think like a cave woman when it comes to fasting. I thing the fast-breaking meal should prepare you for your next fast, not releive you of a fast. In other words, you have no idea when or where your next meal will be. so eat heartily and eat food that will stabilize your blood glucose so that you can carry on during your fasting. That means eat plenty of well nourished protein ( grassfed whenever possible ).Healthy colorful veggies especially green leafy ones. Migraines may be a very strong sign of magnesium deficiency. This is very common in everyone ESPECIALLY pre and post menopausal women. I prefer supplements. bath salts and magnesium oil ( applied topically )to eleviate these symptoms. Have your vitamin D levels checked and make sure that they are on the higher end of the range not the lower end or borderline.

    So basically back up from what you have been doing. Review your diet and consider what you might add or take away from the dietary equation. Are you eating enough when you break your fast? Also when you break your fast, are you eating enough to carry you through the next foodless hours that you will be experiencing. Are you eating enough fat,water and sodium that is so very important.End each day in a nice soothing 20 minute soak in a tub of magnesiums salts…sleep like a baby.

    mary titus wrote on September 9th, 2012
  10. Spot on with this write-up, I seriously think this web site needs much more
    attention. I’ll probably be returning to read through more, thanks for the info!

    eat stop eat discount wrote on March 19th, 2013
  11. May I simply just say what a comfort to find an individual who
    really understands what they are talking about online. You certainly realize how to bring
    a problem to light and make it important. More and more people have to look at this and
    understand this side of the story. It’s surprising you are not more popular because you surely possess the gift.

    Nichole wrote on May 23rd, 2013
  12. Just curious… any long time members still doing IF?

    Or, have you stopped?

    Karl Roberts wrote on October 14th, 2013
  13. been fasting 3 days a week for quite a few years now— haven’t lost much weight but so many physiological issues of age have disappeared or have been muted. I look younger today than I did 5 years ago, and feel like I did in my early 40’s– I’m almost 60. I struggled my whole life with being over weight (300 at one point– and I’m only 5’4″) In the 5 years I’ve been fasting, I might have lost about 10 pounds and weigh about 190 right now. on non-fasting days I can’t over-eat, my stomach has shrunk. Food used to seem so much more important to me; it’s not that it tastes bad, it just doesn’t taste as great…, funny….

    mory wrote on October 14th, 2013
  14. Interesting thead. One commenter alluded to “dry” fasting – no water. Can’t say that that sounds like a good idea.

    I liked Mark’s summary. He shifted from thinking he had to fuel his body every couple of hours to being ok if he skipped a meal every now and then. That approach works for me as well. I go most of the day without eating one or two days a week and the other days have 5 or 6 meals consisting of protein and vegetables most of the time. It’s helped both my energy levels and my ability to stay lean.

    Jake wrote on October 31st, 2013
  15. Hi everyone,
    Dr. Thomas Seyfried Ph.D. is using the Ketogenic Diet and IF to reverse Brain Tumors in mice, and the studies are heading to humans. He believes Cancer is a Metabolic Disease, and cutting out carbs (sugar) and oxygen chamber usage, have major promise in C treatment (tumor types).

    Otto Warburg won the Nobel Prize in Medicine in 1931, and Dr. Seyfried is continuing his hypothesis work.

    IF converts a glucose energy body into a ketosis body for energy, and is actually good for you. I’m doing a 5 day IF to get into Ketosis faster.

    Laura (So Ca) wrote on March 3rd, 2014
  16. “Intermittent fasting has also been shown to reduce spontaneous cancers in animal studies, which could be due to a decrease in oxidative damage or an increase in immune response.”

    …or yet, maybe the non-cancerous cells end up accidentally “starving” the cancerous cells. Perhaps the cancerous cells benefit from a nutritional surplus that is reduced by means of fasting/smaller nutritional intake, or higher demand from healthy tissues (it seems that exercise also slows down cancer in rats or mice, specially if combined with the consumption of caffeine).

    just wondering wrote on June 13th, 2014
  17. “And it all makes sense from an evolutionary perspective”

    What tires me the most is this just-so-story evolutionary/hyper-adaptationist reasoning. There’s very few imaginable things that wouldn’t make any sense at all under a realistic evolutionary perspective, simply because most/many organisms are considerably ecologically generalists, not being strictly adapted to a narrow set of environmental conditions, but able to deal with a reasonable degree of changes.

    Environmental changes won’t necessarily drive specific adaptations (like hibernation) to “cycles” or “patterns” like times where food is plenty versus scarce, but by the mere fact that an organism that is adapted to “enough” food is simply not certain to go extinct if the food sources become more abundant (population will probably increase, but probably rarely/almost never before there were situations where obesity was an issue) or become more scarce (population will decrease, and physical conditioning of individuals will suffer heterogeneously through the population and lifetime of individuals).

    Besides that, and also of critical importance, the “evolutionary environment”, to which most of the current adaptations of an organism evolved, isn’t necessarily the best environment for the organism — it’s the other way around, the organism became adapted to the hurdles of the environment! That’s why there are things like “pests” through invasive species and higher-taxon selective sweeps. Sometimes species that evolved in an environment, adapted to it, are unable to compete with a newcomer that is just accidentally better adapted to that environment, perhaps because it was adapted to an even harsher one, or just has some specific adaptation that isn’t product of an overall harsher situation, but gives it an winning edge anyway.

    To sum things up, even though our bodies are products of evolution, and it can be useful to take that in consideration, we shouldn’t expect a narrow adaptionist outlook to be a reliable guide in discoveries or theories. It’s to be expected that evolution results also in accidental byproducts of several adaptations (or even maladaptations), and these byproducts can imply in better health outcomes for situations that have little to do with replications of the latest range of African environments that our lineage endured. There probably never were a cultural adaptive peak at an “original human condition”, the original humans using the human body at the optimal level. That’s not even a reasonable expectation from the theory of evolution, it’s more like BS one will hear in sci fi stories of Star Trek and the like. And here I am, arguing at length with the internets again. Another evolutionary maladaptation, for sure.

    just wondering wrote on June 14th, 2014
  18. That is a great tip particularly to those fresh to the
    blogosphere. Brief but very precise information… Appreciate your sharing this
    one. A must read article!

    abortion pill wrote on July 9th, 2014
  19. That’s why, Clarine, it is important to review various publications on the subject as well as discuss it with people who have done it for a long time. I only say tat because there are very trustworthy articles on ths subject, this is not the only one. AMD there are people who do this that can support that data here. Good point.

    Mary Titus wrote on September 20th, 2014
  20. As a Muslim, I have to fast from sunrise till sunset for 29 to 30 days a year (during the Arabic month of Ramadan), except on menstruation days (and these have to be compensated some other time of the year). It is also “bonus” to add Mondays and Thursdays on any time of the year. Other “bonus” days are the three full-moon nights in the middle of Arabic months (which are lunar months).

    Duha wrote on January 29th, 2015

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