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. I’m not sure if this has been mentioned, and it may be a bit technical, but here goes. I keep hearing people referencing a fast for “24 hours” and then they eat dinner one night and nothing until breakfast two days later. That’s probably closer to 32 hours. If you want to fast for 24, as I have tried with good results, you can eat dinner one night, and then dinner again the following night. Assuming you eat at the same time – those are 24 hours apart. I’ve found that is actually fairly easy to do, possible sneaking some nuts or soybean seeds if I really get hungry during the day.

    Joe wrote on October 25th, 2011
  2. II am doing Paleo and only eat about every 4 or 5 hours and eat three meals a day with my last meal around 5pm. I am never hungry between meals anymore.
    Is it possible to just skip a meal for a fast? Would that be even close to being effective???

    Debra wrote on November 7th, 2011
  3. Let me get this straight,

    1) Fasting causes increased insulin sensitivity.

    2) Eating a lot causes decreased insulin sensitivity.

    So if we keep fasting once in a while, in the context of not binging during days with food, then we improve our insulin sensitivity, which would allow our bodily cells (including adipose cells) to be more responsive to insulin.

    Therefore, we will get fat once we do this because our fat cells are more sensitive to insulin, and is able to uptake more glucose?

    Confused. How is this going to help promote fat-loss and prevent muscle-loss?

    Peter wrote on November 8th, 2011
  4. By accident I did a 23 hour fast and found it to be not a bad experience at all. I had breakfast and then didn’t have a chance to eat dinner. I felt so good doing this that I decided to try doing it once a week.

    On my fast days I eat an all-meat breakfast (1 egg, 1 beef patty and bacon the last time). Then I do not eat until breakfast the following day. I feel great, alert, strong, energetic and mentally calm. Now I can go to my evening jam session and jam all night without worrying about getting home to make dinner.

    Peter I think this promotes fat-loss and prevents muscle-loss because you are still eating every day. You aren’t starving. You are simply increasing the window of not eating which allows other hormones in your system to do their thing. I think it is part of the process of improving your metabolic flexibility, something lost eating the SAD with frequent feeding times.

    Diane wrote on November 17th, 2011
  5. Our fat cells will become more sensitive to glucose which will keep the insulin levels steady. We won’t need to consume so much food that floods our system with glucose. Just enough to keep the insulin stable. Now that I have been fasting, my glucose levels stay within the 75-97 range.

    Mary Titus wrote on December 7th, 2011
  6. I have been vegetarian since 94 and vegan since 04. I have always stuck with 5-6 small meals a day and done well. If I waited longer I would start getting a headache, telling me I need to eat. Recently I stared the Candida Diet mainly to support my wife who really needed to. In the process I found out that I literally had a wheat addiction that would cause headaches if my levels got low. Since kicking wheat (and corn and sugar) when I get hungry I don’t get a headache any longer. This has enabled me to fast for 24 hours with little discomfort and actually enjoy the sensation of calorie restriction. I plan to soon begin an IF program using the daily 16 hr fast, 8 hr eat method and include a basic muscle building routine. Wish me luck!

    Billy Jack wrote on December 11th, 2011
  7. Good article Mark.

    I have at least 8 years coaching people using IF methods and have found a 12-14 hour fast to be ideal in most fat loss situations. Given this I have my clients do a 3 day system where they eat a large meal mid-morning and another late at night. The next day they eat between 1-4pm and have only water the rest of the day and day 3 mirrors day 1. It’s worked quite well at breaking plateaus in my weight loss clients over the years and I continue to use it today.

    On another note one area I am extremely interested in but see little research on is the idea of food batching. It seems to me that ancient man grew, found or killed something and probably munched on that food or few foods until they were gone or nearly gone. So, if fish are prevalent this week, we catch a bunch and eat tons of fish….then they leave. Next week berries are ripe and we kill a deer so we eat berries and deer for 18 days straight before we catch a wild pig and find some nuts which may last us a couple of weeks. I’ve played with this a bit on my own eating just 3 foods each day for up to 2 weeks before changing foods and beyond being really boring, I actually felt pretty damn good. Thoughts on this concept?

    Jared wrote on December 13th, 2011
    • Jared, as to your comment on food batching. It makes lots of sense to me. I don’t do food batching, as you describe, but I do find myself eating the same thing for days without becoming sick of it. When I do become sick of anything I eat, I quit eating it. I eat once a day, now.

      Mary Titus wrote on December 18th, 2011
  8. Great issues altogether, you simply received a new reader. What may you recommend in regards to your put up that you made a few days in the past? Any certain?

    miracle antioxidant product wrote on December 17th, 2011
  9. I am a wrestler and in my fasting experience i had to drop about 7 pounds and still be hydrated to be able to wrestle at a certain weight. I did a fast starting Monday night and ending Tuesday night. When i woke up in the morning 1 weighed 154 lbs. All day i drank water and ate nothing. I then weighed 150 lbs so i still had to drop 5 lbs so i ran with lots of sweatshirts and sweats on. I got all the way down to 142 lbs in less than a hour.i then drank 3 pounds of water to make sure i was hydrated. i took the hydration test and passed and weighed in at 145 lbs. After that day my natural weight was 148 lbs by eating and drinking anything i wanted to. Fasting helped me lose weight quickly and keep it off!

    Wrestler wrote on December 21st, 2011
  10. Quick question…
    Water whilst IFing obviously great – still or sparkling. But is coffee ok too? Black coffee? Seems too good to be true!

    Joanne wrote on January 27th, 2012
  11. Read “How to Eat to Live” by Elijah Muhammad this book was written in the 60’s. He talks about fasting for 24 to 48 hours and how eating this way will prolong your life.

    Felicia wrote on January 27th, 2012
  12. Thank you for making this post.

    Actually, as a Muslim, fast is obligatory during 30 days at a certain period of the year, from dawn to sunset.

    I did not know about the finding you mentionned in your post about the benefits of fasting. However, I think that not eating for a good period could help better appreciate the food that one has.

    Moreover, if a person is fasting for the Ramadan for example, it helps to avoid eating whenever you feel hungry (except after the set time for breaking the fast). Thus, there is an element of self control.

    Thank you for sharing these data.

    Tiky wrote on February 2nd, 2012
  13. I fast from 11pm-1pm daily. It is working wonders for me. Energy through the roof, gaining strength, burning fat, always in a good mood and caloric management has become a breeze. Counting calories is practically pointless. Quite difficult to eat too many calories in the small 10 hour window.

    ry wrote on February 23rd, 2012
  14. My experience: Since cutting sugar out of my diet, for the most part several years ago, I naturally started skipping breakfasts and kept weight I had lost – off. Giving in to the idea that it is important to eat breakfast saw me gaining weight back. So I skip breakfast most days. (Sometimes I do eat breakfast, but it is usually when I know I won’t have access to good food for most of the day.) My habit for the most part is to go from 7pm to about 11am to 1pm without eating. That is 16 to 18 hours. This is before learning about primal/paleo eating.

    Although, I still have a few pounds to loose, most people don’t believe that I am 50 years old. I look and feel healthy!

    Joyce wrote on March 20th, 2012

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