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Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...

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August 09, 2007

Is Intermittent Fasting Healthy?

By Mark Sisson
607 Comments

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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607 Comments on "Is Intermittent Fasting Healthy?"

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GP
9 years 1 month ago

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

Intermitten Fasting Success
6 years 6 months ago

My fasting experience has been successful. I did it three or four time a week. I know some people did it once or twice a week, but still achieving good results. March marks the 5th year of my IF. I lose weight, stay fit and feel much healthier than before. Though more people should go on the IF way of eating.

MrRoberts
5 years 3 months ago
Just remember NOT to fast right after an intense workout and do give your body a chance to recover completely before start on a fasting program. I agree with some of the users in here that drinking juice on a short fast is NOT ideal since your body will think you are on a low calorie-diet instead of really fasting. I fast on water/herb teas once a week on a Sunday for 24 hours starting after lunch until noon on Monday. Again, the reason for Sunday since it is a quiet day for me and I have done my intense… Read more »
Mel
Mel
4 years 2 months ago

Great explanation, thank you so much. I am starting a once a week 24 hour fast. I will be traveling so will bring along teas and citrus for my water.

Mary
Mary
4 years 5 months ago

Just curious what your IF schedule was like. I just started learning about IF, I would like to give it a try I just don’t know what to do. Thank you in advance.

Naomi
Naomi
5 years 2 months ago
This is interesting, because I have always been one of those people who can’t not eat for longer than a few hours. I my stomach would literally rebel if I didn’t eat, and I wouldn’t then be able to eat without feeling super sick and crampy in my stomach. Lately, I have been intermittently going for like 12 hours without eating, because I have time and access to good food in the mornings, (wake up at like 5 for breakfast), and after about 1pm I usually stop eating until 10pm, sometimes I don’t eat from 10 to 10, and I… Read more »
Giovanni
4 years 3 months ago
I lIke the additions to your book and I lenraed some new things that were very useful.However, I was surprised that you made little mention of autophagy-one of the major advantages of IF. Of course autophagy might mean more to me than you as I am close to 70.I have done a link chase on autopphagy and there is a wealth of information available. Based on that information, I use IF to do cell hardening, strengthen muscle cells and to kill random cancer cells floating around in my body. There is enough information available to justify a chapter in yet… Read more »
Mikie
Mikie
4 years 2 months ago
Hi bud just seen comment and taut would give some advise. Most of your IF should be done while sleeping to make it easier and fasting like 16 to 18 hours each day. What i do is wake up skip breakfast like half 2 i hit the gym so i eat a wholegrain bananna sandwich to carb up and have some energy for the lifts , then have your protien and a small dinner and then at half 6 or 7 have your main dinner and thats your fasting done wait until next day to start cycle over again. And… Read more »
LaPier
LaPier
3 years 11 months ago

Thank you for your input. Your explanation makes the transition achievable. Just to clarify, is it best to eat prior to a workout to maintain best results? I’m an early riser and prefer my training in the mornings which would be prior to the completion of the fast for that day.

Abel James
4 years 11 months ago

There seems to be a great deal of confusion about the idea of fasting… With the so many variables at work, it seems that one beneficial step for fat loss (fasting after a workout to increase growth hormone release) would also be detrimental for muscle-building/retention (a catabolic state due to muscles being “starved” for food). Perhaps the best approach is to see what works for you, evaluate and measure your progress, and tweak appropriately.

Michelle
Michelle
4 years 7 months ago

The problem with juice fasts is you are still taking in massive amounts of sugar, thereby negating any health benefits

Sara
9 years 1 month ago

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. 🙂

kev
kev
6 years 2 months ago

i had similar results…with 48 hour fast…..There is actually some research that say fasting helps de-calcify the pineal gland….basically helps it reset and get all the fluoride and other crap out of your pineal gland.

Mark
Mark
9 years 1 month ago

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.

Faster4life
Faster4life
5 years 5 months ago

Yes, fasting means water only. The moment you take in any external calories you break your fast. Then it becomes a low calorie diet not a fast. Juices are loaded with calories.

Mary
Mary
4 years 5 months ago

so no Tea or coffee?

Kathleen
Kathleen
4 years 5 months ago

Personally I find that drinking tea (no milk/sugar of course) or black coffee does not upset the fast the way juice or other caloric substances do. I just spent several weeks eating one meal a day (except sundays) and felt great by the end; to help me get through that last stretch before the meal I would drink coffee, and it was a nice boost, didn’t destabilize me like calories did. (I felt especially good the week I did zero grains – my main food was almond butter.)

cis
cis
3 years 2 months ago

home-made vegetable juices would seem ok, e.g. cucumber and celery

Mike OD
9 years 1 month ago
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… Read more »
Hazel
Hazel
4 years 3 months ago

Quick question Mike -Will taking ACV with water during my fasting period affect the quality of my fast?? Normally I stick to water and black coffee during my non-eating time, but have been trying to incorporate some ACV into the scheme lately and it suddenly dawned on me that i have NO idea what affect that would have on my blood sugars… thanks!

Jason
Jason
4 years 1 month ago
Thank you for the long post mike! I was curious if it was healthy to do this on a daily basis as most posts only seemed to focus on a “once and a while” or once a week basis. As a new father, student, and having 2 jobs, this way of eating is so much easier for me then the every 2-3 hours diet. I started last night, eating a normal healthy dinner about 12-14 hours before I knew I would be training the next day. I must say that I couldnt be more surprised at my energy level and… Read more »
LaPier
LaPier
3 years 11 months ago

You sound you got off to a great start. How are you maintaining your goals since this last post? That window for you fast is the one I will try, any tips regarding how to stick to a clean lunch when bringing it from home?

Mike OD
9 years 1 month ago

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.

Donna
Donna
9 years 1 month ago

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.

Megs
Megs
5 years 4 months ago
I think that drinking juices and more so mineral based beverages are essential to physical health. keeping in mind that a certain amount of natural sugars are very good for the body. you may choose a more deprivation based fast but the body needs some form of nutrients in order to survive in a healthy manner. I started my fast two weeks ago. I only eat twice a week within a 24 hour basis and plan to go the entire month as a starting point. yes it doesn’t sound but so interminent but i find that my body does need… Read more »
Maggie
Maggie
5 years 4 months ago
Megs Please be careful. What you are doing is definately not healthy. Even Alternate Day fasting is hard on the heart: “This is not a positive report. CONCLUSION: Chronic ADF in rats results in development of diastolic dysfunction with diminished cardiac reserve. ADF is a novel and unique experimental model of diet-induced diastolic dysfunction. [!] The deleterious effect of ADF in rats suggests that additional studies of ADF effects on cardiovascular functions in humans are warranted.” Ahmet I, Wan R, Mattson MP, Lakatta EG, Talan MI. Chronic alternate-day fasting results in reduced diastolic compliance and diminished systolic reserve in rats.… Read more »
mory
mory
5 years 4 months ago
been fasting three days a week for three months– maybe lost a pound. on my eating days, it was maybe 1300 cals of very healthy foods. I run about 10 miles week. I’m about 190 at 5’4″ 34″ waist (rolly polly) very healthy, never get sick— just meant to be chubby I guess? before doing three days a week I was doing two for nine months– didn’t loose then either. I started two years ago with Tuesday fasts and daily 1200 cal days. over two years lost maybe 10 pounds? I’m close to 60, so maybe that’s it? people say… Read more »
Michelle
Michelle
4 years 7 months ago

That is not the type of fasting we are talking about. Eating only twice a weeks is starvation not fasting; however the compressed eating window or one or two 24 hour fasts thrown into the diet is healthy.

Furthermore, your dogma sounds extremely pro-ana to me, being a recovered anorexic(26,4’7,134lbs oh healthy!) I know the kind of things we come to beleive. This is not deprivation for the sake of deprivation, it is about health but it is a fine line.

Please do a little more research on the difference between intermittent fasting and eating disorders.

Crystal
Crystal
9 years 1 month ago

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.

Chris
9 years 1 month ago
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… Read more »
Gracielou987
Gracielou987
5 years 5 months ago

How does that affect your workouts? Do you exercise in the morning on an empty stomach?

James
James
5 years 4 months ago

I don’t know loads about IF, but I’m curious enough I may try skipping breakfast. I did, however, used to run in the mornings before breakfast. I was a bit more into mileage back then than I am now, I can remember going for 6-8 miles before breakfast. Seeing as primal workouts are less demanding on glycogen stores, I can’t see it taking that big of an effect.

sarah Morrow
sarah Morrow
5 years 2 months ago
Lot of people do this, Chris: – fast from 6 pm till noon (your body will do a cleansing during this time, and start cleaning out old broken cells) – exercise vigorously at 11 a.m. or 11:30 a.m. (right before you break the fast) – then have a big healthy meal at noon, right after exercising (it needs to be within a half hour) (your body will use the nutrients to rebuild, repair and rejuvenate) If you do it this way it’s important not to eat anything before you exercise, but eat very healthy foods (lots of healthy fats, carbs… Read more »
Mary
Mary
4 years 5 months ago

How often do you recommend doing this? daily?

Oxybeles
Oxybeles
9 years 1 month ago

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.

Brian
Brian
9 years 1 month ago
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… Read more »
Scott Kustes
9 years 1 month ago

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

Terry
Terry
9 years 1 month ago

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.

Kenny
Kenny
3 years 3 months ago
I definitely agree with this. Sometimes I’ll keep lunch too but I don’t make it a job. I just about always keep breakfast, I’m use to it now. But I decide at the time if I was to keep lunch, if I feel like eating, I eat. I just don’t make it a job or chore. Stress free as possible. I’m doing this in combination with the starch solution and it’s doing wonders for me already. I have been doing the starch solution for the last month and added IF for the last three days. My knees have been aching… Read more »
kim
kim
9 years 1 month ago

My feet hurt!

brian
brian
5 years 7 months ago

hahaha

Abraham Williams
9 years 1 month ago
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… Read more »
Levi Wallach
9 years 1 month ago
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… Read more »
MJ
MJ
9 years 1 month ago
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… Read more »
Joe
Joe
5 years 5 months ago

Hello, I was wondering at time is your 4 hour window

thanks

Farrah Knight
Farrah Knight
4 years 4 months ago
I’d like to add that this is what I do as well. I fast 7 days a week, eating only between 6-10pm, it’s not constant eating but I will have dinner, then maybe a little dessert and a glass of red wine all within this time frame, then I don’t have anything but black coffee till my next day. Every morning I get in an hour of cardio; uphill speed walking or a moderate jog. Then I do some weights all on an empty stomach. I feel wonderful living this way. I sleep better, I am mentally more clear and… Read more »
cis
cis
3 years 2 months ago

Sorry but this sounds extreme. The reduced eating, the hour of daily cardio etc on an empty stomach EVERY DAY…. and your weight is ok now, you can find a somewhat more moderate lifestyle plan now.

Moe
Moe
9 years 1 month ago

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

Moe
Moe
9 years 1 month ago

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.

Patrick
Patrick
5 years 7 months ago

Moe, do not downplay practical experience. Anecdotal evidence has its place in these types of issues where sufficient scientific evidence has not yet been completed.

Wylie
Wylie
4 years 5 months ago

Or you could just try it for yourself and experience the benefits first hand! Placebo or not you’ll look and feel better.

cis
cis
3 years 2 months ago
I don’t feel better doing 2 IF days a week (dinner previous day to dinner today), have lost NO weight or body fat whatsoever (in fact, I seem to have put some weight on and body fat seems to have increased!). During fasting, I got some headaches and have low energy issues: not so much physically but rather I feel unable to do any mental work (even invoicing or playing sudoku feels difficult, let alone creative thinking about where to take my business or contacting clients). Also, I am a fitness instructor, so I am expected to be active, energetic… Read more »
Charlie Rebich
9 years 1 month ago

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

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Jordan O'Hara
9 years 21 days ago
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… Read more »
George
George
6 years 7 months ago

“I plan on a 30-40 day fast (water only) when I’m ready. ”

I really hope you’re not serious, because this is a recipe for serious health problems up to and including organ failure, hair loss, severe weight loss, and even death…

Jordan O'Hara
6 years 7 months ago
Many people complete 30-40 day water fast all the time. However, for the unexperienced faster you would want to be under medical supervison as you have to monitor the body carefully. For the experienced faster you will know already if you can undertake a 30 -40 day water fast. Also you would want to ‘fast prep’ meaning living a ‘very’ healthty lifestyle for as much time as it takes to be in excellent health – otherwise the toxins released during 30-40 days could cause complications. I’ve completed 5 – 15 day water fast with no supervision and no trouble and… Read more »
Joe
Joe
5 years 10 months ago

You posted this in January so you’re probably dead by now, but if you’re still in the process of “prepping”, please don’t starve yourself for 40 days. You will die. You’re a lunatic.

Jordan O'Hara
5 years 10 months ago
I’ve never starved myself and your generalization that fasting for 40 days causes starvation is incorrect. A complex organism in a true fasting mode has no direct biological relation to the state of starvation…starvation only occurs when all the bodies reserves are depleted and you start converting energy from the vital organs. A person in starvation mode would be hard to miss – skin would be tightly wrapped around all the bones and they would look like they should be dead. I’ve been fasting periodically for many years so my body is well adapted for this lifestyle. Anyone without years… Read more »
Ashleyy
Ashleyy
5 years 5 months ago

i find it interesting how so much of this parallels the eating patters of an anorexic/bulimic.

i should do, i am both.

cis
cis
3 years 2 months ago

According to Bragg, starvation does not occur in a 30-day fast. It is only if you fasted, over 40 days that you would incur starvation. He should know because he did lots of (distilled) water fasts and healed lots of people that way (and lived a long and healthy life). However, I simply cannot accept the highly ketonic state they cause – it makes me feel very sluggish and unwell.

Shannon
Shannon
2 years 11 months ago

Props to Jordan, who seems to really know what he/she is talking about. I’m curious as to whether you ended up taking on the 30-40 day fast, now that it’s October, 2013?

Jake
Jake
4 years 4 months ago

Hi Jordan,

What do you find to be the benefits of alternate-day fasting?

Rose
Rose
9 years 20 days ago

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!)

Peter
Peter
5 years 6 months ago

Hi,

I have done the master cleanser and lost about 40 pounds, How many days have you gone and how many have you lost. I am now a hardcore grok, so no fear in gaining the weight back after losing it.

Peter

Cheryl Diamond
Cheryl Diamond
8 years 11 months ago

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.

Patrick
Patrick
5 years 7 months ago
One thing about water fasting is that it forces your body to use the energy stored to maintain activity. That’s its only choice, since no energy is entering the system. Because of this and the fact that fat is the body’s optimal source of energy, IF is excellent for decreasing BF levels. I certainly suggest that everyone try short fasts at first, as recommended in the comments previous to mine. Maybe 16-20 hours at first. Maybe one day out of the week. Something like that. As for you regaining some weight (did you mean fat or just BW?) after you… Read more »
cis
cis
3 years 2 months ago

Cheryl, I agree. I also think this is more of a problem for women than for men. Men seem to do better on IF diets (also the “5:2 diet”) and similar. Women may need to keep a more balanced food intake (including enough good fat) for hormonal balance, for instance.

Rose
Rose
8 years 11 months ago
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… Read more »
SarahAnn
SarahAnn
6 years 7 months ago

I know this was 3 years ago.. but reading this comment made me want to cry (happiness and hope)! I hope you’re still strong!

Linda
Linda
6 years 4 months ago
I’m real inspired at this post. In my 20’s I IF’d after two childbirths and lost about 75 pounds after each child. I kept it off until age 35 when my job and a divorce got too stressful. Then at 40 I was disabled and jumped to 235 pounds with hypothyroidism. I fasted off 35 pounds three years ago. Then got into cycling and lost to 187. Then injured a knee for a year and up to 216. Last week decided to IF like when I was in my 20’s. I mainly fast and only eat a full large meal… Read more »
mm
mm
5 years 9 months ago

Soymilk? I hope you realize soybeans cause so many problems from reproductive organ disorders to hypothyroidism to brain shrinkage that they are basically well-marketed toxins, right?

Mariann Sidor
Mariann Sidor
4 years 4 months ago

Wow…that is amazing weight loss!!!! Did you notice having a lot of loose skin after losing so much weight so quickly? I enjoy fasting but never wanted to lose more than 10 lbs at a time so skin can catch up!!

atumu
atumu
8 years 10 months ago

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

Mitchell
Mitchell
8 years 7 months ago

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.

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[…] 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… Read more »
Jordan O'Hara
8 years 6 months ago
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… Read more »
Jeff
Jeff
7 years 23 days ago
Boy I don’t know about just eating apples and oranges cause you would be a twig literally starving wouldn’t you? If you have NO protein you have NO muscle. Which means you can pump all the iron you want and its not gonna do anything if you can even still lift it. Won’t your body start eating your muscles?? Can’t you do a water fast like two to three days a week then on the other days eat 4 to 6 meals with lots of protein, complex carbs like red and sweet patatoes and veggies?? What do you all think??… Read more »
Tanya
Tanya
5 years 9 months ago

Interesting. Too intense for me, but I do a cleansing fast ever quarter. Stanley Burrough’s Lemonade Clease. I love that for 10 days or more. It renews my resolve to stay healthy. I started at 317 lbs now I am 227 lbs. Not sure of a weight goal, just a how I feel and look goal. These stories though encourage me. I commend anyone who sticks to what they believe in.

Tanya
Tanya
5 years 9 months ago

Actually Master Cleanse. It’s a whole lifestyle change. Eating veg. after a 10-60 day cleanse. Small amounts of fish organic only. I don’t striclty adhere, but I do get as much organic food as possible. I still do pork and beef a few of times a year.

Greg
Greg
5 years 8 months ago
Correct, absolutely correct. Young children and adolescents need at least 3 meals a day. Young adults to age 30 probably only two. From age 30 or 35 to age about 50 one meal a day is ideal and beyond age 50 only one meal every two days. I currently eat only once every two days. The single meal should include all food groups and, (unless you are trying to lose weight), enough calories to keep the weight stable. Absolutely the worse diet you can have is ‘grazing’; this overworks the Beta cells in the pancreas (these produce insulin) and continuous… Read more »
mory
mory
5 years 4 months ago

greg, I love your type of knowledge, can you recomend books, or sources where an exposition of your thoughts can be found?

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[…] Is Intermittent Fasting Healthy? […]

G man
G man
8 years 5 months ago

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.

MrsBehaving
MrsBehaving
5 years 9 months ago

I prefer the evening window because it allows me to have dinner with my family. I struggle with not eating in the evening when I have to cook and the rest of the family gets to sit down and enjoy it. I’d rather not eat while I am at work. I use my breaks to read my favorite books or magazines instead of eating then enjoy dinner with the ones I love. 🙂

Faster4life
5 years 5 months ago

Not everyone is the same. What works for you may not be ideal for others. For some people it may be easier to sleep through the first 6 to 8 hours of their fast. what better time to be hungry than when you’re asleep?

Lucky Joestar
Lucky Joestar
4 years 9 months ago
I do so in the evening simply because I’m not hungry in the morning. I’m at 84 kilograms, by the way. My healthy weight range is from 60 to 80, so I’m aiming for the happy medium of 70. Last Sunday, I started doubting the often repeated advice that breakfast was necessary for weight loss, and I stopped eating breakfast, starting my day with just water. At my age, 43, I don’t think I even need lunch. The usual mantra is that you’ll eat an entire warehouse full of food in the six hours a day that you’re not fasting.… Read more »
G man
G man
8 years 5 months ago

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…

Jordan O'Hara
8 years 5 months ago

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.

cis
cis
3 years 2 months ago

I love my breakfast… I feel hungry in the morning (within 1 hour of being awake) and it is hard not to eat then. If I don’t eat (ignore tummy noises) because of time-pressure or as an experiment, I then start feeling weak by lunchtime and weak/grumpy/hating life by 2pm. My diet is fresh foods, mostly veggies, some fish, fruit and nuts/seeds, no dairy, no grains.

G man
G man
8 years 5 months ago

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.

Jordan O'Hara
8 years 5 months ago

Woops! Sorry about the typo. Yes I mean Supper (Evening meal).

camille
8 years 5 months ago

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.

Jordan O'Hara
8 years 5 months ago
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… Read more »
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[…] shunning food can be quite satisfying. To learn more about the benefits of fasting, check out Is Intermittent Fasting Healthy? Or, if you have some travel in your future, seriously consider reading this one: Fasting May Stave […]

Monica
Monica
8 years 2 months ago
I can offer a comment to G’s question about why some of us choose the evening as the eating window. I used eat only during the day but it often proved challenging to refrain from eating at night if hubby was cooking something that smelled fantastic. Not to mention air popped popcorn (one of my weaknesses). As a result I was sure I consumed more calories than I was aiming for. Since reading this website and trying the reverse – black coffee between 9 and 10, water with lemon all day and breaking my fast with fruit, then easing into… Read more »
Jackie
Jackie
8 years 2 months ago
I have really enjoyed reading all of these very informative posts. I found my way to IF through a diet called The Doctor Johnson’s Up Day Down Day Diet. He suggests eating no more than 500 cals one day, then eat to satisfaction the next. But he had also talked about intermittent fasting, but said that “most” people could not do that, so their goal was to stay under 500 cals. But being the hard headed person I am, I was determined to not be “most” people. I have been fasting every other day for 2 weeks now, and find… Read more »
Anna
Anna
4 years 8 months ago
This page hasn’t been active for a while, it seems, but still a wealth of information and sharing. After an accident resulting in severe hip injury, I was extra-motivated to lose weight. At 40, I was about 75 pounds over. Factors such as difficulty exercising due to pain and reduced mobility, plus a change in my living situation, led me to what seemed an easy and natural solution: I just stopped eating alone. Sometimes I would eat one or two meals every day, sometimes I would go up to 4 or 5 days fasting. When I do eat, I eat… Read more »
Jordan O'Hara
8 years 1 month ago

Excellent Jackie! With strong will power and our advancing knowledge one can achieve a level of health that is un-heard of ever. I hope to be dry fasting 3 days and one day eating within this next month. Right now I’m still only 1 day on one off. Definitely I too fell much better on my fasting days. Good luck and stay strong!

Big Ragu
Big Ragu
8 years 1 month ago

I’m interested in starting this diet. Help me out! What does the one day on and one day off consist of? Do I eat anything I want the first day, then on the next day just drink water? HELP!

Jordan O'Hara
8 years 1 month ago
From some experiments that I have read from the National Library of Medicine it seems you can eat as much as you want on your eating day and still get the health – life extension benefits of fasting. The benefits are much more powerful then caloric restriction and you don’t have to get so skinny. The eating every other day such as 1 day on – one day off extends life generally about 30 – 40 percent an average suggest many experiments. The longer in between eating the longer the life extension. Reason seems to be (my theory) that the… Read more »
Tyler
Tyler
6 years 7 months ago

“Even Fruits don’t want to die (be eaten) so they have a substance call fructose which is poison for mammals”

This is absurd- the purpose of fruit is to convince animals to eat it, therefore spreading it’s seeds. Fructose attracts mammals VERY strongly, which is why fruits contain it.

Shane
Shane
6 years 6 months ago

Fructose seems to serve both purposes, but let’s not be fooled: it is a metabolic poison in any significant quantity.

Ricky
Ricky
5 years 9 months ago

According to Michael Pollan, fruit are used by plants to attract eaters (humans, bears, etc.) so that seeds will be distributed and more plants will be produced. Plants bribe us to spread their seed; they don’t know that these days humans usually put seeds and pits in garbage bags.

mm
mm
5 years 9 months ago

If fructose was made to poison humans it wouldn’t be a leptin-disruptor as well, since that would incourage us to eat even more fruits. More likely, fructose in wild fruits was only found in small amounts and while your liver doesn’t like it much it would have been better tolerated than in today’s selectively bred fruits.

ricky
ricky
8 years 30 days ago
I have been following an IF diet for about 2 weeks now and i feel great. on the days i go to work and school I fast for 20 hours and eat around 1500 to 1800 kcal in a 4 hour window. I feel completely free from having to plan my day around my meals I now plan my meals around my day. On days i don’t have school or work(the weekend) i follow a paleo grazing diet with one “cheat” meal. The results are amazing, my wieght has gone done and my strength has gone up. I also have… Read more »
intermittent fasting
8 years 22 days ago
Tony
Tony
8 years 16 days ago
Jordan, your last comment belies a fundamental misunderstanding of biology – “Even Fruits don’t want to die (be eaten) so they have a substance call fructose which is poison for mammals; luckily the fruit has anti-oxidants to protect itself from the poison fructose which also may protect us from the fructose to some degree.” This is ENTIRELY false. Many plants rely on their fruit being eaten by animals to disperse their seeds – the animals eat the fruit and then crap the seeds somewhere far away, where the seeds never would have gotten if it weren’t for the animals. Many… Read more »
Jordan O'Hara
8 years 16 days ago
This is not Entirely false. We’re talking chemical warfare and plants are damn good at it. We only eat the failures. Otherwise they do their best to kill us. Why should it be any other way? We seem to be in the midst of an “evolutionary arms race”, meaning plants evolve to make us carry their seeds and/or to fend off being gobbled by poisoning us, and we in turn evolve to process those very toxins, or at least to somehow neutralize them. However at this point we are still greatly damaged by fruit toxins – i.e. fructose. Fructose triggers… Read more »
Tyler
Tyler
6 years 7 months ago

If a plant kills the animals which spread it’s seeds- it will die to. Fruiting plants have a symbiotic relationship with the animals that eat the fruit- not an arms race.

Fructose will not kill or harm mammals in the levels they obtain in the wild. It’s only dangerous when concentrated and making up a large percentage of your diet (like in soft drinks). No wild mammals will get diabetes or insulin intolerance from eating an occasional fruit.

mm
mm
5 years 9 months ago

This is a major part of the reason why I prefer to eat as fewer plants as possible, preferably zero.

Karl Roberts
5 years 1 month ago

Do you realize that the bees are responsible for the fruits we eat today?

The bees simply cross-pollinate the pollens onto another flowers, fruit trees etc.

What makes the bees want to cross-pollinate?… Fructose!

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[…] I’ve mentioned before in relation to intermittent fasting (IF), fasting is known to significantly increase HGH secretion. (Grok’s survival depended on […]

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[…] how does Intermittent Fasting help you? Mark Sisson of Mark’s Daily Apple sums it up quite nicely: “A recent article in the American Journal of Clinical Nutrition gives a great […]

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