Is Intermittent Fasting Healthy?
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:
Sponsor note:
This post was brought to you by the Damage Control Master Formula, independently proven as the most comprehensive high-potency antioxidant multivitamin available anywhere. With the highest antioxidant per dollar value and a complete anti-aging, stress, and cognition profile, the Master Formula is truly the only multivitamin supplement you will ever need. Toss out the drawers full of dozens of different supplements with questionable potency and efficacy and experience the proven Damage Control difference!
Subscribe to Mark’s Daily Apple feeds
Posted By: Mark Sisson
Thanks for the advice Mary. It is tough eliminating carbs from my diet espcially since I am a sugar addict. I am trying to ease in to that though, cutting sugar first then going for the breads and pasta. I will keep all this in mind when/if I try fasting.
Yes, it is tough. You must decide what foods you want to be addicted to. Sugar is not healthy. Anything that will rot your teeth as easily as sugar should not be consumed so regularly. Just imagine what it can do to your insides.
Good luck on your journey.
Mary
Hi,, I’ve read about i. f. and it sounds really good. I have one concern though. I am 5’4 and my weight is around 110 pounds. I eat well, and although I am vegetarian, I ocasionally smoke so I want to kick off the habit and try some fastings as well. The most I’ve done water fasting in the past is 2 or 3 days. However, I want to do a cleansing, empower my brain, clean my body. My only concern is how much could I do the fasting if I am mainly skinny, and I have a good metabolism? I guess my point is, how to fast in order to detox my body and my mind, without really losing more weight? What do you recommend? Is I.F. for me? Or should I try a juice fasting instead? Thanks.
I do IF on a daily basis. I do it for its ketogenic characteristics. My body runs better on high octane ketones.This meaning, I eat a normal balanced ketogenic diet in concert with IF.I think that fasting in its own right, cleanses the body without any help especially if you have a healthy metabolism. I am not a vegetarian and cannot really give you any advice that I would feel comfortable with BUT, I do think a juice fast would be counter-productive unless it is done with vegetable juice. Sweeter fruit juices have sugars that will swiftly impact your blood glucose. This would cause your insulin levels to rise and glucose levels to drop, which causes stress to your metabolism. Everyone should strive to keep both glucose and insulin levels under control.
Keep in mind that the purpose of IF is not to eat less food…it is to eat less often to allow the digestive system to complete the digestive process. By allowing the process to complete itself you will be amazed at how your body will cleanse itself. TMI, I know but this is significant. I have a nice BM that follows within 2 hours after eating my fast-breaking meal. Please note, that I did lose weight but it was only 22 pounds in 2 years. That’s not very fast. If I wanted to do this without weightloss. I eat within a 4 hour periods each day. So between 2:00 and 6:00 is when I eat. I eat whenever I want including snacks and 2 meals, which is my standard rule. The difference with that is, once I break my fast with a large caveman meal, my hunger is much milder througout the day.
So if I ate according to my standard rule, I am sure that I would not lose…at least not as much.
I would like to add that doing IF consistantly for 2 years, I have concluded that this isn’t something to do on occasion unless you do it for religious reasons. I believe that it should be done with some type of regularity to maintain healthy metabolism. But, that’s just me. Good Luck,
Mary
Plenty of research out there about IF and it’s benefits for the glucose metabolism and it’s neuroprotective stress responses. IF is not CR (Calorie resistriction) yet has many of the same health (and more) benefits. That is pretty amazing in itself. Here’s just one study:
“A consistent hormonal response to a decrease in food intake in rodents, nonhuman primates, and humans (30, 31) is a reduction in insulin levels and an increase in insulin sensitivity. We found that mice subjected to IF exhibited decreases in serum levels of glucose and insulin to levels at or below those in mice fed daily but with a 40% reduction in caloric intake. The ability of IF to alter fasting levels of insulin and glucose was independent of overall caloric intake.”
“The findings of this study suggest that IF can enhance health and cellular resistance to disease even if the fasting period is followed by a period of overeating such that overall caloric intake is not decreased.”
both from study: Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake
If you improve the state of your glucose metabolism, you will lose fat. IF (even if just 1-2x a week) + Paleo foods will get you lean and healthy…IFOC (IF on Crappy foods) doesn’t work as well….simple as that.
You can also read about different approaches and 100s of comments about how people are using IF here: >a href=”http://lifespotlight.com/health/2008/02/27/intermittent-fasting-101-how-to-start-part-i/”>Intermittent Fasting 101
sorry….messed up the last link above…here it is again:
Intermittent Fasting 101
Great info Mike OD,
This is stuff that I read before doing IF. You put it all in a nutshell.
Thanks
Hi, I have been eating a ‘caveman’ diet for two years, eating 5 meals/day, eating around 100-120g carbs/day.
I exercise 4x/week using heavy weight compound exercises.
On those occasions when I have purposely skipped a meal on rest days, I notice a definite reduction in strength in my weights workout the following day.
May be i’m doing something wrong but I can’t combine IF and weight training without a measurable negative impact on strength.
I’d really appreciate any thoughts/comments.
From what I understand growth hormone production is stimulated with a combination of factors; Decreased blood glucose levels, increased blood protein levels,carbohydrate-restricted diet, FASTING, increased protein diet, free fatty acid decrease, PGE ( a good eicosanoid ) Stage IV sleep ( circadian sleep ) and exercise.This can be found on p. 191 in Protein Power by Dr. Michael Eades. There is more info on this but I would logically assume that if I have been consuming a lifestyle that is opposite from what I have listed here, it would indeed take some time for the body to adjust to the new lifestyle.Once the adjustment has been made, you should deveope muscles that will have a better sustainimg power.I think that it is worth taking the time to do it. I am not a weight trainer nor am I an athlete but I feel the best that I have ever felt…ever. I plan on running in a 5K race in November. During this race, I will just be finishing up my fast. I will not eat my first meal for anotther hour. By-the-way, I fast everyday.
I have been doing a complete fast with one 24-hour day per month for nearly 30 of my 36 years as part of my religious experience. I can vouch for how it is amazing to refocus the mind: I used to believe that I derived this benefit from all the practice I got from trying so hard to think about things other than food; so nice to know it is from a physiological effect too!
http://www.webmd.com/heart-disease/news/20071106/fasting-may-cut-heart-risks
I have been doing a one day a week 24 hr fast for the last 4 weeks. It gets easier every week. I find my strength and cardio workouts don’t suffer.
Also, during the days when I’m not fasting, I eat about 100 calories every hour. This combo works great for me.
In 2005 I used to follow the Warrior Diet religiously every single day. I was 21 at the time, but was growing a bit thick around the stomach. Fasting works, and it works good. WD makes you eat one large, very large meal a day and I’d normally have a huge salad with tons of protein and fats from evoo and such.
Every morning I would wake up and do strenuous exercise including kettlebell work and a lot of dive bomber pushups, hand stand pushups, bridges, etc. lots of bodyweight work. Not only did I drop weight but I looked much leaner than I ever had. No dizzy spells or anything.
Once your body adapts, it’s like any other normal day. I’m doing more Anabolic Diet eating, but cleaner and now I’ll start fasting again once a week. Good article!
IF and Clean low carb food- perfect! Toss in strength training to complete the package. Howl at the moon.
I am wondering whether or not it is okay to fast when breastfeeding. My daughter is 14 months old, but eats little solid food, mostly the breast milk. I am easing into primal eating, and it would be significantly easier with fewer meals. I’ve been told over and over that you’re not supposed to diet when breastfeeding, but I have 100 lbs to lose, and I hope to lose 50 of them at least before I get pregnant again, which is likely when I stop breastfeeding. I feel like I’m in a loop against weight loss by any form except just eating better food and exercising. I know that will help some, but I’ve had trouble being consistent and so I haven’t really lost anything.
Anyway, back to fasting:
Would the shorter eating window be okay (Dinner and a snack) If I ate a lot of nutritious foods and a pre-natal vitamin?
Always better to wait until after breastfeeding. I tried dieting during breastfeeding (low fat) and my milk got thinner and my baby a hungry screamer. Remember, on IF you will be dumping toxins into your bloodstream the baby. Also, your baby needs consistent calories and YOUR caloric requirement needs are higher when breastfeeding. I would try the IF but add a teaspoon-tablespoon of coconut oil (lunch and dinner) before eating to keep milk supply steady and healthy and not compromise baby’s growth. Most don’t recommend IF if pregnant or brfeeding. Consult your and baby’s doctor.
I can only offer up my opinion. I breastfed all 3 of my children. If I had it to do all over again, I do believe that I would be better at it the way I eat now. I do advocate eating low carb for the healthiest way to incorporate intermittent fasting. I would also use fats liberally in my diet. Fasting is nothing new…it is just new to modern civilization. Also, IF doesn’t really make you lose weight. It facilitates weightloss by allowing complete digestion.I did quite well losing weight after adding If but all in all, I only lost 15 lbs a year. A total of 30 lbs over a 2 year time frame. However, I was fifty when I began doing this and I know I would have had better weightloss results at an earlier age.
Make sure that you are consuming plenty of fluids for obvious reasons.The idea with IF isnot to consume fewer calories, just consume fewer meals.Hope ths helps.
Cheers,
Mary
I would like to add something else. If you have dinner at 7 PM and not eat breakfast until, say 9 AM the next morning,you’ve spent 14 hours fasting naturally. Not much different from an extended fast.
Thanks, Mary
I can make that 14 hours just fine. Maybe even up to 16, if I’m inactive. Still pretty blood sugar sensitive. I’ve been easing into this lifestyle, Trying not to be too harsh on my family (my mom complains about how she can’t seem to omit that one last eggyolk, and then turns around and eats boca burgers…) And my husband’s best friends are named Carl (Jr. of course) and Jack, who lives in a box. I’ve gotten my meals to be pretty primal, and even some snacks. Once the stress hits, though, I attack bad food. Ugh.
Anyways, I figure that if I can keep the discipline of an eating window, perhaps it will be easier to avoid the bad foods of the world.
Now to kick my kid of her Cheddar Bunny habit…
Hi Sara,
You have your work cut out for ya, I see. I am sure that our primal sisters had stressful moments. What did they do for that? Anyhoo, I’m enjoying our IF chats.With IF I do tend to eat less of the bad stuff. IF is work and I don’t want to mess that up with a hershey bar ;-0
I have been fasting a total of maybe close to 50 days on and off (mostly 5 hour fast got me prepared for longer fast) some 48 fast diffcult need more mental control) and 24 hour fast simple if you keep it up)
I have had great sucess..got discourage from a 1 day standstill i know that was silly (suffer from alot of doubt i swear if food talks to you it does on the inside to)
and switched back to diet pills for 3 days and horrible thoughts in my head.
I had wls 7 yrs ago lost over 200 pds i look amazing i must say but i been trying for the last 3 years to get to my (last goal of 120) and i have tried alot of things that i knew wasn’t right..But since i started fasting besides learning a new relationship with myself with out food (which i thought i could never live without and i know if i chew even a piece of gum i have to raid the fridge i have problems with food)
IF not hard it has been rewarding. Lol i been tip toeing around a 30 day fast i am going to have to work on that. I even thought about keeping up the 48 fast its a bit more diffcult but reguardless fasting has saved my life i think besides the fact i think GOD gives us more than what we need to survive. The health reasons must be way higher than having mcdonalds 4 times a day.
I totally support intermittent fasting!!
Holy Cow…who the heck want to take 2 years to lose 25 lbs?? Mark, I think your original post got hijacked! Over at Bodybuilding.com, I regularly see people completely transformed from 30% fat to under 10% for contests…in 3-6 months! Now I’m not interested in that lifestyle, and I don’t want to eat 6 flippin times a day, and I think fat is essential… BUT… these comments have done nothing to sell me on IF. I think, if done how you intended, it should have 3 benefits: 1. make you feel good, 2. give you the mental strength to not panic every time you don’t have access to food, and 3. help you lose weight (if you’re trying to do so) or maintain (if you’re already there.)
Food is not evil!
Agreed! Why anyone would think 25 lbs in two years or whatever sounds good, I got a bridge to sell ya! It takes way less time than that if you are eating less. This thread is also full of one or two people posting over and over. Ugh. Internet pontificators.
I would much rather lose 25 lbs in 2 years than to GAIN 25 lbs in 2 years. I know this as a fact because I did both.
No food is not evil, that is why a love IF…I get to eat all the food I want as long as it is low carb. I just make sure that I eat within a 4 hour windoq. I think that it is great to be able to eat a poop load of food AND lose weight while doing it. PLUS, after eating a poop load of food, I get to have a nice BM. My stomach is flatter without doing any form of exercise. My blood lipids and blood glucaose are stable. I can be physically active without the worry of passing out. I’m not trying to sell you on IF, I am just sharing my experience.
Mary, I regretted posting that because it does seem like I was referring to your posts, when actually it was other posts that I thought turned things around a bit. Unfortunately, it was the “25 lbs in two years” that stuck with me the most, as that would be awfully frustrating for me. You’re right though, it is much better that you didn’t gain that amount instead…you’ve created a lifestyle/weight you can maintain.
Marie, no worries. I actually lost 30 lbs in 2 years and have 10 more to go before reaching my goal. I post about intermittent fasting because I think that I adapted a pretty ideal manner of which to do it successfully and I just hope to be able to help someone to do this without it being a fad diet.
I fasted from Sunday at 7pm to yesterday (Monday) at 5 pm…definitely a first for me barring the flu
It wasn’t too difficult because this sinus infection has me feeling pretty bad; and I didn’t feel “light” or refreshed either because, again, I feel crappy from illness…but, I will do this again because,for me, the biggest reason is my #2 above: overcome that panic that comes in from missing a meal..teaching my body that it’s okay, I’ve got plenty of “stored energy” for use!
So while I believe humans are designed physically and culturally to eat…to share meals… IF is a nice tool to have.
IF does not remove the culture of eating and sharing meals. That is something else that you have to teach your body. Not only is it okay to skip a meal ( althoough, I do not believe that is possible ) but once you break your fast, meals are even more enjoyable
and sharing meals are even more rewarding.
We are in agreement
very interesting reading – I started Fast 5 two weeks ago now but I don’t do it every day – only Monday through Friday and then I eat normally on Saturday and Sundays (although I do low carb on those days) For me it has been liberating to stop eating so much – I seem to be the kind of person that when I start eating in the morning I can’t stop so to not start until 2pm is much easier – then I eat what I want until 7pm but do try to keep the food healthy – keeping it low carb as much as possible… I feel great…
I just discovered IF via a news article about its popularity recently in the UK. I’ve always wanted to try fasting for a spiritual experiment and to shed these extra 50lbs I’ve been carrying for too long. I also have a panic reflex in not knowing where my next meal will come from and I overeat everyday. Last Fri I was forced to fast having no income lately due to economic situation and came across the news article about IF the same day – coincidence? This was two days ago. Yesterday I ate one meal and today even though I could have eaten, I chose to stay with IF. I know my relationship with food has been dysfunctional for a while and am hopeful this might mend it a good deal. Being comfortable not having access to food can be very useful for stress reduction. Not depending on food / meals for peace of mind is valuable. Cutting my food spending in half can mean more money toward other things. I just sort of panick inside at the thought of not having my ‘daily bread’ so to speak. It’s in the lords prayer for crying out loud. Anyway, I can say I started IF out of financial distress but will continue IF by choice now that I have information that it won’t kill me to refrain from food every other day. I plan on treating myself to the pizza buffets on feeding days though but I have a suspicion that those cravings will diminish as my relationship to food improves over time and my choices become wiser. Now is no time to be judgemental on the feeding days. It’s about reducing my food bills, waistline, and depression/stress all at once. Counting carbs and calories, hours and AM or PM of when to eat, and what to eat on feed days just creates complications and stress for me. I believe in KISS. If today was fast then tomorrow is feed and it will be pizza buffet if that’s what I want. It’s one step better than the buffet every day which has been my routine and any step forward is growth. I think that as my ‘panic’ symptoms decrease over time with IF, so will my subconcious need to binge on unhealthy foods. My stomach is growling but I’m excited at the same time. Thanks for listening.
hey John welcome – I’m doing it differently to you – Fast 5 is fasting everyday except for a 5 hour eating window… I need to eat an evening meal with my family for social reasons so this is what I have chosen – I don’t ever feel the need to pig out though – I eat muesli at 2pm when I break my fast – I have a snack with my son after school at 4pm (cruskits with salmon or a boiled egg or even just vegemite) and dinner with the fam at 6pm – normal meat and three veg type meal – I try to low carb but if I feel like a potato I will have it – try to stay away from white rice and white pasta though… empty calories… so even though I don’t count calories I’m aware of which foods provide me with more nutrition…
it’s great – I’ve lost three kilos in the last five weeks… and still going down…
just some ideas for you…