Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
19 Mar

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:

Post Workout Fasting

Modern Forager: My IF Success Story

Conditioning Research: IF Reduces Inflammation

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Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. 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.

    Shadeburst wrote on June 28th, 2011
    • Clearly you’re new here.

      Lauren wrote on August 8th, 2011
    • 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.

      BT wrote on October 13th, 2011
  2. I wish I could IF…but ever since going primal the foods just taste SO DARN GOOD.

    SlenderGrok wrote on July 18th, 2011
  3. 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!

    Milla wrote on August 28th, 2011
  4. 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.

    James Fortmann wrote on September 28th, 2011
  5. 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.

    John Goodner wrote on October 13th, 2011
  6. 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

    Tizz wrote on October 13th, 2011
    • 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!

      beth wrote on October 13th, 2011
    • 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!

      beth wrote on October 13th, 2011
      • 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?

        Tizz wrote on October 13th, 2011
        • 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 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 truly the definitive guide to IF.

          beth wrote on October 16th, 2011
      • 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!

        iwstamp wrote on December 28th, 2011
  7. 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!

    Lucy wrote on October 26th, 2011
  8. 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!

    teresa wrote on November 29th, 2011
    • 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.

      Milla wrote on November 29th, 2011
  9. 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!

    teresa wrote on November 29th, 2011
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    Brenda Kimberley wrote on February 18th, 2012
  11. 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.

    anonymous wrote on February 19th, 2012
  12. 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.

    david wrote on February 26th, 2012
  13. 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??

    Michael wrote on March 15th, 2012
    • 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.

      Steve wrote on March 21st, 2012
  14. 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?

    Amy wrote on March 27th, 2012

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