How To: Intermittent Fasting
After the great discussion last week following the 1 Meal vs. 3 Meals news post, we thought it was a great opportunity to follow up and delve into the nitty gritty of IF. Practically speaking, what does IF look like? Today we’d like to focus on the “window of eating,” a dimension of IF that got people talking last week.
Any brand of fasting can already seem a little daunting for the newcomer. (But for those whose impressions of fasting involve hunger strikes or gaunt figures sitting in meditation, we think you’ll be pleasantly surprised.) Reading about some options, and knowing your efforts will indeed be rewarded with true health benefits, makes the leap a little more inviting.
Let’s first put this on the table: there is no one way to do IF. The only real guideline is that, as always, the food you eat should be healthy. (It’s pretty clear how we choose to characterize that.) In addition to the substantial health benefits, the simplicity and flexibility are what draw people to IF.
As Mark said, he enjoys mixing it up beyond the use of one approach by missing meals naturally or on an unplanned basis in addition to full day fasts. Let your choice(s) fit with your personal/family schedule, natural rhythms, and your personality (some of us are meticulous planners and some are more spontaneous – “and that’s O.K.”). The point of IF is this: episodic deprivation takes your body “off the track” for a while and allows systems to reinvigorate and recalibrate (also known as up-regulating and/or down-regulating gene expression). Check out Mark’s previous post on IF for more info on the research and nifty benefits of fasting.
Here are a few ways to IF (in unofficial terms):
Skipped Meal:
As Mark alludes to in his comment in the 1/3 meals post, he likes to miss meals naturally or on an unplanned basis. When we listen to our bodies rather than blindly follow routine we find we’re not always hungry when mealtime comes around. Let yourself skip a meal when this happens, or plan a meal skip during a convenient time.
Condensed Eating Window:
As shown in the comments from last week’s post, this is a popular option. The day’s food intake is condensed within a set number of hours, often somewhere between four and seven hours. The timing of this window varies depending on the individual’s schedule and preferences. The time since you prior meal or until you next day’s meal becomes the fasting period.
Early and Late:
For some, this option is more easily managed than the condensed eating window. The day’s food intake and nutrients are balanced between an early meal and later afternoon/early evening meal.
Single Twenty-Four Fast:
Most people choose to have a normal dinner and then fast until the following evening. Others choose to extend the fast until the following morning. For many people, this can be a weekly routine. Others may integrate it on a monthly basis or as an occasional event based on their sense of progress/plateau.
Alternating Day Fast for Week (or more):
This approach is often credited with a deeper “cleansing” character. Some people do it once or twice a year. Others make a seasonal commitment. You can choose to drink only water or include teas/small amounts of juices during fasting days. On the alternate days, some people choose to eat normally, and some opt for reduced caloric intakes.
One tip: During your “window of eating,” however long or brief it is, don’t feel that you should eat more than you might be hungry for. It’s a unique opportunity to listen to your body’s signals. It also serves as a way to “prove” to your conscious brain that you can survive quite nicely on smaller amounts of food and that you don’t need to “make up” for those temporarily lost calories. Of course, eating according to the Primal Blueprint at all times whether fasting or not means that you are constantly refining your fat-burning skills. This, in turn, means that you are not so dependent upon regular meals to sustain normal blood sugar levels, physical energy and mental acuity.
Interested in trying IF for the first time? We’ll highlight the “condensed eating window” approach (one option among many) to get you started. This approach, particularly with a fairly extended window, is very doable and can seem less daunting as you get started. Choose your own timing and length of window based on your schedule and preferences. If you can’t decide, you can consider condensing your eating between the hours of eleven and 5:00 p.m. Look for a corresponding IF menu in this week’s installment of “Eat This Today, Feel Good Tomorrow” later on today.
Be sure to send your feedback. We’d love to hear your results!
*Florian Flickr Photo (CC)
Further Reading:
Modern Forager: My IF Success Story
Conditioning Research: IF Reduces Inflammation
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Posted By: Worker Bee
meant to say ‘at the age of 46′
Humans can go without:
Air for 3 minutes;
Water for 3 days; and
Food for 3 months.
My PB is one month.
Just started doing my first fast in a long, long time. Hunger is my constant companion right now, but thankfully I am going to bed. Hopefully I’ll wake up closer to normal. Haven’t decided how long I want to take this. Being hungry makes you think of breaking the fast in the morning (if not sooner), but I was hoping for another day, up to a week tops.
From what I have read, a week is nothing, and will give me a chance to see what life is like well beyond the point of hunger.
I usually have a pretty good willpower so this ought to be nothing, but the desire to eat the last several hours seems more from a strong desire to enjoy the taste of food and not from any physical “need”.
Made it through work. That made it 41 hours from my last meal until I broke my fast when I got home from work. Last hour of work I had the beginnings of a headache with some jittery feeling which felt like a lack of calcium. I also had a craving for liver. Again today I wanted to eat for the sake of eating and enjoying food, but not as bad as the day before. I will just monitor my hunger and be sure to avoid gorging. Will probably do it again.
If you are hungry during a fast it is usually thirst and an ‘empty’ stomach not hungry because there is a difference. Since you are burning fat your body will just use your fat for fuel.
I would like to know the best workouts during a fast and the best food for breaking a fast.
So inspired by the research presented here and the email newsletter from a few days ago I skipped lunch today. Well, if the truth be known I forgot to take it with me… Anyway, I figured this is the chance to try skiping a meal.
I have been eating primal blueprint for about 6 weeks now and one of the immediate benefits is I don’t panic when I get hungry. Todays fast- just skipping lunch- was no big deal. I guess I’ll try this once or twice a week and see how it goes.
I guess the biggest impact for me is, aside from the effortless weight loss, taking back control of hunger and eating. No longer am I slave to the carb and the hunger panic attacks.
On a side note some of my friends, family, and co-workers think I am bat poop crazy, so I am taking the Primal Blue Print on the down low. For those who are truly interested in what I am doing I preach it and send them the primer .pdf.
I was doing a lot of intermittent fasting a year ago. I would go 36-48 hours per week. I went from 270 down to 245 and felt great. The more I did it the easier it got. Once I stopped I began gaining again and now am at 290 and finding it very difficult to fast. I had been eating mostly vegetarian in between fasts but am thinking that this primal diet might make fasting easier for me and eliminate the rebound gaining I was experiencing.
hi mark, i been fasting 2 times a week in the past three weeks for fat loss purposes, i was in the pb eating style 1 month before starting, and i look and feel awesome, i want to know if a 36 hour fast represent any benefit vs a 24 hour fast, thank you.
Researchers from the Intermountain Medical Center Heart Institute in Utah recently conducted a study to determine the potential health benefits of participation in water only fasting. We wrote about this at http://www.specialtycareservices.com/?p=1747.
IFing is great, saves money and time and is super easy to do,just don’t eat!!!. Also as an extra guys stop eating ANYTHING WHITE!!!! I bet my left testicle the majority of obese/ weight gainer gain weight by eating too much rice/pasta/pizza/bread. Another huge one is DO NOT DRINK CALORIES!! So many people go by drinking coke/beer/martinis/ juices/ sodas/milk. Unless you are drinking a post work-out shake drinking calories is useless as most of what you digest is PURE Carbs. In my case If i drink the night before I do exercise the following morning to counter the carbs and also help my hangover.
If you find fasting too hard just go with Tim Ferris slow carb method, which imo is more difficult because its not as simple as “only eat once a day”. Btw if you think you can loose weight slowly by calorie counting you are wrong. Yes you might get far, the very moment you eat more calories than before you will gain weight, that is why you must exercise (preferablly HIIT- high intensity interval training) to keep your metabolism up
I am going to start IFing the begining of next week. I have been eating a bit of rubbish after lent, and as I have a holiday until next week, I plan to get it all out of my system.
i have dabled in the eat stop eat way and found it ok. But just recently I have had a really bad bout of acid reflux (along with having IBS), and tried to stop eating after 5, which really helped me.
I also remembered that I read a book on fast-5 a few years back and got another copy, so had tried that for a few days as well, 12 til 5, and it was so good. I felt so much better, nice and light.
Its a bit awkward though knowing what to eat with my IBS, not high fibre because I cant handle it. I was told to eat white stuff.!! Bit annoying, but will have to see how it goes.
Anyone got any advice? Thanks. Rach
Rach, check out GAPS. Full expanation of why and how to avoid white foods. Then move on to PB, with the explanation of why replacing grains with nuts (as many GAPSers do) is unwise. Between them, you should be able to piece together where the “eat white” mantra came from but why it’s not going to help you in the long run. Healthyhomeeconomist has an article with a monstrous comments string about this as well.
hi,
I just started out with Primal Blueprint (well, a mash-up of PB and Robb Wolf’s PS). I’m only on Day 3.
At what point do you guys think I can add IF to the mix? Does my body first need time to get used to eating differently or can I just try it immediatly?
I used to IF when i was a carb eater. It is just harder mentally because your body will crave carbs and quick energy vs. moving over to burining fat from your body for energy. Once you have been primal for a month it will be super easy to IF and you will find that you are more focused and have more energy when your body dips into its fat stores to fuel your day.
I would go for it if you want, especailly because you can see how the experience will change over time when you are more fully primal!
For your first one it is kind of nice to start by eating breakfast (or having a primal fuel shake) and then skip lunch and dinner and go to bed and try to make it to lunch the next day.
I worked at a preschool where all we did was feed the children. They arrived at 9am and I always assumed they would have had breakfast already- however I was still required to provide a morning snack (usually crackers or dry toast with jelly). I then followed 2 hours later with a heavy meal . Again 1 1/2 hours later with some type of dessert and a snack again while they waited to be picked up 2 hours later. I was horrified at how much these kids eat all day. I have been fasting one day a week since I was 30(12 years). I find my body responds well to this. I stop eating after Mondays dinner and resume eating Wednesday morning. I guess I am lucky – I never have hunger pains. In fact sometimes I find that sometimes I have to convince myself to eat again- because I do feel much fresher and revived(energetic) when I go a day without eating. I have 3 children and I am a busy active mom who never slows down and fasting has never interfered with my energy level in any way. I guess to each their own.
Mark, I am curious about how biochemistry is being affected by fasting. I am new to primal (1 month) and have for years been eating regular meals to keep my blood sugar stable, which keeps beta endorphins (BEs) from spiking and then leading to a crash. The crash would always lead to cravings for sugar/carbs, but I was still eating whole carbs. But now I am confused. Were BEs not really a factor after all? There are times I feel like I could skip a meal, but am afraid because I really don’t want the cravings to come back!
All I know is that by eating primal these last weeks, my cravings are almost non-existant…the first time in too many years. And my energy is way up. Maybe this question is too vague, but if it makes sense I’d love to know more!
I don’t know much about BEs but I used to eat to keep from getting sugar crashes. My husband and I used to even call it getting “hangry” hungry and angry.. and it was all about carbs. I used to fast while i was a carb eater and it was just a bigger struggle because mentally and physically my body wanted carbs and would fight it and make it difficult. Now on PB my body is indifferent to the fasting no real issues because your body is now used to burning fat for energy and provided you are not 0% body fat it will access those reserves to keep you feeling full. There is a difference in feeling “hungry” and having an empty stomach AND being thirsty. Many “hunger pains” are actual “thirst” pains and many other “hunger pains” are actually just your stomach feeling empty but you not physically being hungry (weak, tired, lacking energy) just get out of your head and into your body and go for it. Don’t fear cravings, commit and do it. Just skip dinner and breakfast and eat at lunch or skip lunch and dinner (go to bed early) and eat at breakfast. Or just skip one meal and start slow.. just qualify what you feel with what is really going on.. do you THINK you are having a craving because you THINK you should or are you really hungry.. maybe you are thirsty.. just give it the 10 min test. Drink some water and then see how you feel in 10 min!
Thanks Beth, I hadn’t thought of it that way, that my body is now getting used to burning fat instead of carbs. I have gone long periods between meals and not noticed significant cravings. I have a feeling one of these days I will skip a meal without even noticing! It really is pretty easy.
Exactly! That is the best way to do your first IF.. when you notice that you have “missed” lunch because you were working or busy once you notice it just wait till dinner — First IF done! Also a crazy thing happens once you get through a few hours .. you have MORE energy.. I am excited for you and for your first fast!!! Take Care!!!
“many other “hunger pains” are actually just your stomach feeling empty but you not physically being hungry (weak, tired, lacking energy)”
This right here.
My very first revelation when I started to get healthier over a year ago was the realisation that hunger does NOT equal an empty stomach and there for should eat, Hunger is when you feel tired and lacking in energy, THAT’S when you should eat.
Such a simple idea but one so so many people sadly don’t understand.
A lot of people read about IF but end up being confused about where to start – and therefore don’t. I like the way you stress that there is no ONE way to do it. Try what seems practical for you and see how it goes. Great approach.
Warning: blood glucose. The brain uses most of the glucose in circulation. In between meals the liver has to look after the brain. It converts protein to glucose. This protein comes from your lean body mass–chiefly your muscles. A tiny snack of a biscuit or even a couple of grapes every couple of hours is all you need for adequate blood glucose levels.
Clearly you’re new here.
I have just read up on blood glucose, and it is important to note that even when starving blood glucose remains the same…but the body actually needs a little more glucose than it makes under duress, so there is an argument for eating a few 100 cals of rice ( good starch ) to enable good brain function. Check out the “Perfect Health Diet ” blog on glucose.
I wish I could IF…but ever since going primal the foods just taste SO DARN GOOD.
This is ideal for me. Eating when youre not hungry is not natural because hunger is the signal that you need food, and, well, if you’re not hungry, don’t eat. Sometimes I have a whole ton of nut butter before a workout and just dont eat anything for the rest of the day until late dinner because I’m simply not hungry. Sometimes I do a conscious fast, but most of the time its pretty natural!
I’ve almost completed my 24 hr IF and I feel great. I’m thinking clearer than I have in a long time and not hungry at all.
Okay, I’ve been doing the diet thing for about 6 months, jumped on the workout plan about 4 months ago and I have to say it has been working. But I am now down to 15 to 16% body fat and would like to get down to 10%. Yes I’ve been guilty of eating to many carbs. Yes I’ve been guilty of cronic cardo. But it doesn’t seem to matter how strict I am I just have hovered at the same weight with no change in fat for the past two months. Today is my first day trying IF, how often will I need to do this to break the cycle. Will once be enough to start seeing results.
I am interested in trying IF and would like to know what is the best time of day to start IF? I work from home and sit for 8.5 hours and I also exercise and watch my calories and have been stuck at a Plateau and think that this would help break it. If you can send me an email or comment I would appreciate it. Thanks
I do a daily fast starting at 8am and not breaking until 12 noon the next day.
Also if you want to do a full on 24 hour fast (which I also love) it is easiest(in my opinion) to skip dinner go to sleep and eat a late lunch the next day to go a full 24 hours. Some days I am not hungry for lunch during my daily fasts and so i just skip it. On the weekends I try to get in a long bike ride or jog under 75% of my max heart rate before breaking the fast so sometimes that means i am not eating until 2pm… just take it slow and go with the flow. If you are primal already it will be easy since your body already burns fat for fuel and so you will not have the same hunger cravings as non primal people. You will get to a point where your stomach is “empty” but the “empty” feeling is NOT hunger, it is just empty. it is fun when your mind starts to make that distinction!
One other good idea about plateaus.. cut out nuts if you are eating them.. i tend to eat more than i want to admit so I had to stop having them around…another one to cut out is dairy. Just try it for 3 weeks and see if you break your plateau…oh and make sure to get 8hrs of sleep each night!
Well I rarely eat nuts so thats not an issue but i do eat 1 Chobani yogurt everyday and I use 2% milk when I make my replacement shakes or protein shakes. Ive just started replacing 2 meals a day with replacement shakes. So by not eating/fasting what do you drink during that time to keep you full? And how many days before you see pounds lost?
I mis-typed my daily fasting window it is from 8pm-12noon the next day. Not 8am-12noon. When I fast I do not drink anything except water and coffee.. check out http://www.leangains.com/ for a lot of information on fasting. I do not a lot of meal replacement drinks unless they are really a meal replacement and then i mix them with water and only use Primal Fuel to keep it all in the low carb/good fat area. I cannot tell you how many days it will take for you to see a loss and if you are really close to your ideal body weight you might not ever see a loss on the scale but just notice a difference in how you look/measurements. At some point you are replacing fat with muscle and that is when the scale can mess with your head. I put mine away in April and have not taken it out.. I could probably stand to lose about 10 more pounds but the scale was making me do silly things to try to see a loss/difference like not drinking water in the night so that the next morning I could weigh in at less. Also when you are losing fat sometimes your body holds onto water while it is transitioning the fat away so it will reflect differently in the scale. I would start skipping the 2% milk, eat real food most of the time vs meal replacements, keep your carbs under 100 or try to go for 3 weeks under 50 carbs per day and kick your body into ketosis and then judge your progress by measurements or a before/after photo for 3 weeks… and then if you want validation get on the scale. And again you should really check out http://www.leangains.com/ truly the definitive guide to IF.
Great advice beth… all three of those things are my downfall! I do fast every day, for about 22 hours (I take weekends off…).. but dairy, almonds and 5 hours of sleep are my nemisis!
Hi guys, I’m pretty new to this primal business, but have been thinking about trying IF for a week or so now. I’ve decided today is the day – only question I have is that I get very shaky, dizzy an headachy if I haven’t eaten for a few hours.. Will this just go away after trying IF a couple of times? Any advice is appreciated!
What is the minimum period of time before a fast becomes worthwhile? Just slipping breakfast? I remember hearing about the magic hour where the mega fat burn kicks in but was it 14, 16 or 18 hours! Personally, I would find missing breakfast to be the most sustainable plan. But do you need to do this everyday or would a couple of times a week suffice? Just finished 18hr fast and tucking into delish tuna salad!
yes, the benefits are maxed at the 18 hour mark; when I do a full fast I like to get a workout (LHT) in at this point, and I get peak performance. However, I wouldn’t worry too much about it; there are great benefits to IF throughout. Besides, if you factor in sleep time, and skip breakfast, you’re getting over 10 hours fast time (assuming you sleep enough!) which will give you lots of benefits.
also just wanted to ask, I have not been exercising – am I going to negate all my efforts and lose muscle while keeping the fat? have been sticking to a largely pb diet with a few strays at the weekend ie junk food and beer!
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some people fast because they believe in the Lord and that they are feeding off the Lords spirit. that’s why some people fast, not only to loose weight and things.
I find what works for me is the following: If I’m hungry I eat; if not I don’t.
For any followers of TCM you will have read that our organ systems operate in a rhythmic fashion. Each day is like a single breath in and out to our bodies – ideally, with the morning to mid-afternoon being an optimal period for intake of nutrients and the late afternoon, evening and nighttime, a period of elimination and rebuilding. Whether it be one or two meals a day, or a series of snacks spaced out over several hours (three concentrated meals seems too much to me personally), consumption of primary protein foods beyond 2pm or so is inadvisable as both stomach energies and available protein-specific enzymes have significantly fallen off by this point in the day, making digestion less than efficient (after all eating isn’t always necessarily about quantity, but about what the body can use). Of course, with shift work and artificial lighting circadian rhythms can be thrown for a loop.
We as humans are quite flexible and adapted to periods of fasting – as may have been the norm for us in environments where food supply wasn’t plentiful. Such practices can also be beneficial for those who don’t pay attention to their specific needs and find themselves not hungry because their bodies are still in need detoxifying in a period of time where food would generally be welcomed.
Re: anorexia – it can be due to both psychological disorder and intolerance to specific foods or their chemical components (e.g. histamine intolerance). The consequences of food/chemical intolerance can have physical/psychological consequences that can certainly put one off food. I speak from personal experience. The burden on me as an individual is to determine what foods my body tolerates and go from there.
LOL…. never really thought about it but my normal eating pattern seems to be a cup of coffee with a 1/4 to 1/2 a cup of heavy cream around 9 in the morning or so and a decent size meal somewhere between 4 and 9 pm… would this be considered some form of IF??
I believe that the heavy cream is a no-no with traditional IF (if you have coffee it usually calls for 1-2tbsp of skim milk). But if this routine works for you and you are staying healthy then absolutely keep at it!
I would make sure that your single meal does meet your caloric needs for the day and your macros are properly proportioned. Even in a cut, one “decent” sized meal could be too little or off balanced to maintain your metabolism and health.
Hi! So I’ve tried to fast a little bit for week now. I can’t say if I’ve fasted long enough yet but I’ve at least have been skipping which means I have been going about 6 to 8 hours during the day of not eating. Fasting has seemed to be giving me good results (I’ve lost 2.5 by doing this just this week!), but since I stopped eating lunch sometimes I feel really good (more energized and better about my body). But then there will be times where I don’t feel so well (when I want to eat I feel like I can’t eat solid food with out puking or very light-headed). Also, I feel like I am really hungry but like I also feel sick at the same time so I can’t eat anything. Am I doing something wrong or should I just do this once or twice a week?
Since starting the lifestyle a couple of months ago, I’ve noticed that I naturally skip meals because I’m just not hungry. I am planning on trying a full day fast to see if it will jump start my fat loss. I think IF is perfectly natural and if you really listen to what your body is telling you, your body will tell you to do it anyway.
hi,
I’m currently trying to lose weight. Today Tuesday, is the second 24 fast I do. I did it last wednesday. This whole week I haven’t lost any weight and I’m wondering why that is if I pretty much deducted a good 2000 calories by fasting two days. Has anyone experienced the same?