August
2007
Is Intermittent Fasting Healthy?
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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. I continue to use grazing as my main fueling strategy.
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.
Further Reading:
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Technorati Tags: intermittent fasting, evolution, paleo, longevity
I used to do (once upon a time!) papaya juice fasts for 24-48 hours. While my whole system seemed to enjoy the “rest”… I dont think there were any long term beneficial results.. I think intermittent fasting is good for head and heart
gp in montana
I knew a guy who did a juice fast one day a week. He said it cured his sleep issues and gave him greater mental clarity. Haven’t ever tried it myself. I’m way too much of a foodie.
Only problem with a juice fast is that you may be defeating the purpose. Many forms of juice are high in sugar and might lull one into thinking they are fasting when they are not really. I think you have to achieve that true low blood-sugar state to start prompting the desired changes.
I can personally attest to IF working wonders. Most people especially in the gym are so brain washed into thinking they need protein every 2-3 hours or they go into a catabolic state and wither into nothingness. I say the body is smarter than that and can do with what you give it.
Personally I do a daily fast and only eat from 1-7pm taking in enough calories that I would normally take in and focus on lots of protein, quality fats and vegetables. I mix in some carb up days whenever I need them for a more explosive activity such as playing ice hockey.
So far I have lost 10lbs of fat, gained 5 lbs of muscle and hover at around 8% BF. I have plenty of energy in the morning to do a strength workout 3x a week and add in some walking and hiking. Needless to say I had to see for myself and I did not lose any muscle during the fast but rather gained and lost fat. I am sure my LDL and BP have gone down, I have more focus in the AMs with only a cup of coffee (and I only need one to last me a whole day) and my life does not revolve around food and I enjoy my meals when I have them.
Best part is IF is a lifestyle, not a fad fast. You can do a 16-18hr fast daily(like I do, 24 hr fast 1-3x a week, or just fit it in whenever. That’s not even to say the healing powers of fasting go back 100s of years.
Sorry for the long post, but as a fitness professional and working with many people with chronic illnesses, I can’t stress this lifestyle enough.
sorry just to clarify too, it’s not a reduced calorie/calorie restriction diet, it’s just a smaller window of eating with the same healthy calories (within 10%) I would normally intake in a day. Also the fasting is strict water and only coffee for me, no sugar added. I also add in some apple cider vinegar and fresh lemons during the water fasting periods.
Mike
That sounds worth it! I believe i’ll give it a try, thanks for sharing how well it works, i’m convinced. Oh, i always drink water with a fresh squeezed lemon after a good work out.
Mark,
I have a friend that did drank juice for her fast. She did not complain about being hungry, it didn’t bother her not eating, You’re right, it does defeat the purpose. I told her i did not think drinking juice was a “fast” that she was just sacrificing eating.
I’ve fasted for 24 hours on water only. I do feel better. Monday night to wednesday morning may be difficult. An easier 24 hr. fast would be to quit eating on say Saturday 2:00pm and eat again 24 hours later Sunday at 2:00pm. It seems easier, anyway.
Hi Mark
Inspired by Art Devany, I’ve been doing IF for a while now - combined with a low carb / paleo approach - and find it is realtively easy to stick to. I’ve leaned out a little bit from it and it actually frees up time from food prep.
Eades wrote about this earlier int he year on his blog too.
The method I use is typically to eat only in the evenings - like the Warrior diet or http://www.fast-5.com/ It is realtively easy to eat nothing during the day and feast at night. Loren Cordain had an article on this in his paleo newsletter a while ago
http://www.thepaleodiet.com/newsletter/newsletters/PaleoNewsletterVol1Issue3.pdf
saying that the evidence suggested that typically hunter gatherers would tend to eat big once a day. Which is sensible when you think about it - life was feast and famine in general and this approach mimics the same hormone drives.
IF you search pubmed for “intermittent fasting” there are loads of interestig articles. There are a few on my blog too.
I read it too fast and thought it said Intermittent FLASHING. Keep’in cool in the summer!
Seriously, as I initiate a dramatic change in lifestyle to a Primal Diet, I have attempted to IF in the evening and it is too difficult at this time because of the already drastic reduction in caloric intake.
However, I am able to sustain on a High Protein Shake (Meal Replacement) at 5:20 AM until a 12:00PM lunch weekdays.
Honestly, I am not ready for any food consumption that early in the day. Shake and DCMF for breakfast.
While I think that intermittent fasting is reasonable within the context of how we evolved and life prior to farming, I do have one caution. If you are susceptable to gout you may not want to fast or try it in short bursts and build up to longer ones. I’ve had a gout attack flare up practically every time I’ve tried this (voluntarily or not). Fasting tends to increase uric acid levels and increase your risk of having an acute attack. That said, losing weight will significantly lower your risk for getting gout so I am working on lowering my weight and taking the med’s necessary to stave off an attack at the same time.
I was doing a shortened eating window like Mike OD up there (MOD, is that you?), but was having trouble getting in enough calories in a 4 hour window. I’ve since switched to a 24-on, 24-off plan and I’m enjoying it. I don’t have to gorge as much to get enough food, I don’t have to feel overstuffed, and I can maintain my bodyweight and activity. I’m doing 6:30pm to 6:30pm of fasting and then 6:30pm to 6:30pm of eating, usually four meals (dinner, breakfast, lunch, light dinner).
Scott Kustes
Modern Forager
Michael Eades had some great write-ups on IF’ing earlier this year. I’ve been doing low-carbing (which had already become second nature) with 18/6 IF’ing since then. All you have to do is skip dinner or breakfast most days (no snacking!), which is pretty easy if you’re working.
My feet hurt!
I like what’s called low carb in this context. I’m referring to an earlier post where Mark describes a lunch salad. I like eating this way. I don’t know if I have my food/energy level dialed in or if I’m just more naturally aware I’m in need of a nap (no constant supply of energy coming in). Anyway, the post has inspired me to fast, today. I’ve done it irregularly (which is the right way I hear) from reading Devany’s blog.
What kind of exercise are people considering on fasting days? Mimic the ancestor and walk a lot like I’m in search of food? Maybe an occasional run and throw a rock like I’m aiming for small tree rodents?
I normally do 3 exercises (from a mix of about 30) at high intensity 2 to 5 days in a given week. I’m skipping that stuff today.
After reading about this last Fall, I started doing IF, and have continued to do it with good results. I generally eat from about 6pm to 10pm at night and fast the test of the time. It is a good weight-management tool. After loosing some weight initially, I’ve stayed pretty steady for the last 5 months. This of course is without making any concerted effort to lose, but it sure is nice to not have to worry about how much I eat or even what I eat, as long as most days I eat what I feel is an optimal diet for me healthwise. So I wouldn’t say there’s no plateau for IF’ers. I think there are plateau’s for just about any eating plan. But I also think IF makes it very hard to regain weight and also potentially has some great health benefits on top of it’s facility in helping one lose weight.
It was nice reading the posts. I have started this way of eating two months ago and have noticed incredible results. Mostly, I fast for 19 hours and eat in a 5 hour window. I have lost weight and inches, have more (lots more) energy, sleep better and seem more alert. Generally, I eat whatever I want to in my eating window, but since the weight loss has slowed down, I am considering making some modifications and lowering my carbs. A couple things I noticed–the flavors of all foods seem more intense, so be prepared for fruits to seem too sweet, and be careful to taste your food before adding salt.
You asked about exercise…well I will be 69 tomorrow, work full time and exercise 5 times a week. I do yoga 3 x and work out at a gym with a private trainer 2 x. I do all of the exercising in my fasting mode and have had only one time that I dot dizzy when going from lying down to standing quickly. That may have been due to dehydration, so I try to keep my fluids up during the exercise phase.
Looking forward to learning as much as I can about this way of eating.
MJ
This IF stuff is becoming quite a fad in the fitness world today. As interesting (and seemingly logical) as this article was, it lacks solid research to validate some of its claims. Much ‘promising’ research has only been done on animals. Take a look at this for more info:
http://alanaragon.com/an-objective-look-at-intermittent-fasting.html
PS… Don’t get dragged in by weight loss anecdotes! Many people will experience weight loss simply because they are NOT eating as much as they used to, because, well, their available eating times are significantly reduced.
Have many of you tried the Master Cleanser by Stanley Burroughs. Its the one done by Beyonce with the Madal Bal Syrup. I am actually the US distributor of the syrup and thought some of you might be interested. The Master Cleanse makes fasting a bit easier than juice fasting because you get more calories from the syrup yet you still give your digestive system a rest. Over the years working with this diet I have heard so many miraculous stories that I really believe periodic fasting is the missing link in western medicine.
Be well,
Charlie Rebich
[...] Is Intermittent Fasting Healthy? [...]
[...] Why Intermittent Fasting May Be Healthy [...]
Hi,
I have been doing intermittent fasting (eating every other day) since January of 2007. I only use water on my days off food. Many people I explain this to say it sounds to difficult for them. However I found the body adapts and gets use to the routine, you have to stick with it or it becomes difficult. That is the only trick to it, just maintain the routine and you won’t be hungry on the days off, but if you cheat and make exceptions your system gets confused and you will have trouble. When people ask why your not eating today, just say you are detoxifying today(which is true), don’t say fasting or they may start to judge you because they may not understand etc. I’m also now a 100% vegetarian with I am enjoying very much and have never felt better in my life. I also completed a long fast (healing) in January for 14 days (water only) this was more difficult and I don’t recommend anyone to do this without a lot of knowledge on it first and even medical advice from a Doctor who knows the subject. I plan on a 30-40 day fast (water only) when I’m ready. The intermittent fasting will always be part of my life and I just would not be happy going back to eating food every day. If you have any questions I checked the notification for resposnes to this post. God Bless!
Hi I was just wandering around looking for more information on fasting, I myself am on my 8th day of just water, I am feeling so much better, I havent cheated once and I started at 242lbs and now Im at 217lbs, the weight came off quick in the begining and now I loose about 1lbs a day, I am so pleased that I dont feel hungery I never thought I could even go 1 day without food. So to anyone that has doubts( You can do it!)
IF may be good for your health but not for losing weight. As soon as you eat the next day you start gaining it back at least for me.
well it has now been a little over a month and as I said I started at 242lbs and now Im at 192lbs. I have now started eating a little veggi broth and every other day a mashed up veggi like a carrot, I mash it so it digests faster and easyer, for me this whole thing has had to be a change that will be with me my whole life, you see my grandmother died at 700lbs, my mother is 450lbs and I have a younger brother that at 22 weights about 360lbs so my fasting has been to correct my eating habits and make the change that will keep me around longer for my 3 children, I cryed when my kids got excited that they could give me a hug and fit their little arm’s around me all the way, I feel great inside and out, I will never make excuses again!
I have being on a 20-hour daily fast since 04-01-07 and the result has being amazing.Prior to this fast ,i was lethargic,having chest pains,weighing 83kg(height 5ft 4inches),depressed.presently i am weighing 65kg which i have maintained for past 6 months.I have never experienced so much energy and happiness in my life.I am focused and rearing to go.I eat as much i like after 6pm daily and stop eating at 10pm.i have not being sick since i started this program.I hope this helps someone
Yeah same here atumu I have been doing 20-hour daily fasts on water for nearly 2 years I dunno if its working but I am about 54kg 5′7. I eat as much as I want anytime really. Sometimes I start at 8pm, sometimes I start at 5 - 5:30pm. But no earlier than 4:30PM. When its cold and rainy and I have got nothin to do in the evening I just start whenever.
[...] While a lot of people caught up in our hectic culture would suggest that this is normal weekday practice, we’d suggest (and these studies do as well) that a one-meal routine isn’t the best way to go. As Mark has shared the past, grazing remains the ideal (if difficult) mode for daily fueling strategy. For most of us, three full meals a day aren’t always possible, but the body has a remarkable resiliency to carry us through on the days when it just ain’t happening. Yet, it’s still the goal. That said, there’s room and considerable benefit in shaking things up with intermittent fasting. [...]
One meal every second day would be the best lifestyle for humans-(super). The meal should be of the highest possible nutrition such as oranges and apples and only small amounts eaten over a few hours. If one absolutely feels they need more calories then adding juicing to the meal would work. But remember the trick is to provide only what the body needs nothing more and nothing less. All cells in their natural state are immortal until debris is introduced (caused by eating) which leads to cellular death-(aging). Since humans have no other method of cellular stimulation - (needed to live) besides eating we are stuck with eventual death. To reduce the speed of cellular death we need to eat only what is required for stimulation allowing human life using food types that have built in cellular protective characteristics such as anti-oxidants.
[...] Is Intermittent Fasting Healthy? [...]
Why does everyone choose to do an eating window
at night? I much prefer to do breakfast thru
lunch and then fast for the rest of the day.
It just makes more sense to me. I have only been
trying it a few weeks just to loose some additional fat to increase my running speed. In the past the easiest way to loose weight was to
concentrate on limiting my evening meals. It also
frees up more time for you to do other things…
like the exercise of your choice.
I like your concepts, Jordan. You would become
really lean and effecient on that type of diet.
Getting going on it would be an adjustment though…
Regarding the eating window. My theory behind eating a super only instead of breakfast or lunch is this: Digestion takes allot of nerve energy, if you eat breakfast and lunch the body is busy assimilating food all day. If you avoid eating breakfast and lunch, you instead detoxify all day (repairing) and you have all that extra nerve energy to use on what-ever you want…work etc. Some of the Free E-Books on my website discuss the NO breakfast approach to health.
Jordan,
Now I understand…you mean supper instead of
super, right? I thought at first you were saying
that eating once every other day would make you
a super human.
Woops! Sorry about the typo. Yes I mean Supper (Evening meal).
Mark,
I think you might have to do a more clarifying post. I don’t think IF is meant to be long periods of starvation, and it seems some of the people responding think that is what you mean. People SHOULD eat, but there are benefits to intermittently not eating. I’d love to hear more about what are acceptable intervals and what is just plain starvation.
First I should mention that fasting and starvation are two different things completely. During fasting the body uses Ketones for energy built primarily from fat reserves. During this time the body cleans house…removes any debris and attempts to rebuild any damages that it finds. Starvation only starts after all possible Fat and lastly muscle reserves have been depleted-basically you would look like a walking skeleton with some skin on it before you begin to starve. This takes many months to start for the average size human.
Starvation with an IF lifestyle is impossible in my opinion. IF generally includes eating one day and fasting the other. I practice this lifestyle. I take in vegetables and fruits in liquid form every second day - no solids. I then Dry Fast (no water – no food) the other day for about 36 hours. (Dry fasting only recommend for experienced fasters) In total I go for over half the year without food or water, additionally I do at least two 15 Day water fasts. I maintain a weight of 190 pounds and I am very physically active. If fasting every 2nd day is too difficult then even 1 day a week would be very beneficial to the body and mind. For anyone truly serious about adopting a lifestyle involving fasting then you may wish to visit http://www.fastingconnection.com. This site has fasting MD’s who are very experienced with supervising fasting. It was a great help to me when I was just starting a transition to this lifestyle. Remember… we are not nourished by the amount of food we consume but rather by the amount we assimilate.