In an eating window intermittent fasting plan, you set a specific period of time for your daily eating “window”, and all caloric food/beverages must be consumed within that period of time.  As soon as the first bite of food/sip of caloric beverage enters your mouth, your window is “open”, and when you take your last bite/sip, it is “closed.”  I have seen eating windows as short as one hour and windows as long as 10-12 hours. I would never personally consider or even recommend a 10-12 hour eating window; that’s just not enough fasting for most people to get the results they are hoping for.  An eating window somewhere between 1-8 hours is more typical, and should give most people better results. My first foray into an eating window was the Fast 5 plan, written by Dr. Bert Herring.  In Dr. Herring’s plan, you have a daily 5-hour eating window.  I think that a 5-hour window is a great starting point for many people, but you will need to experiment with a variety of window lengths to find what works for you. While personally experimenting with window-length, I also tried an 8-hour eating window, which is one promoted by other intermittent fasters.  For me, 8 hours is just too long, and I don’t lose any weight following an 8-hour eating window.  That doesn’t mean that an 8-hour window won’t be perfect for YOU; it just doesn’t work at all for ME.  As I said, you should experiment to find which window length works best for you.  Our bodies are all very different, and what works for me might not be the best plan for you. In the Fast 5 plan, which I suggest as a great starting point, Dr. Herring personally uses the 5 p.m.-10 p.m. period of time for his window.  He does say that you can choose whatever 5-hour window works best for you, but I think his recommendation for 5-10 p.m. is genius. Let me explain. When I first started, I wanted to maximize the number of eating opportunities available to me, so I used a 12:30-5:30 eating window.  That allowed me to eat a full lunch and a full dinner every day. Sounds great, doesn’t it?  Well, if you are like me, you can fit a lot of food into a full lunch and a full dinner.  Weight loss was VERY slow, because I was eating a LOT of food every day. When I re-read Dr. Herring’s book, I realized that several times throughout it, he mentioned eating “one meal” each day in your 5-hour window, and suddenly everything clicked into place for me. Instead of trying to maximize eating opportunities, I needed to find a window that would allow me to feel satisfied, but without 2 full meals every day.  When I shifted my window to one that opened at 5 p.m., I had much better results.  The timing of my 5-hour eating window made a tremendous difference in my overall success. I don’t always wait until 5 p.m. every single day to open my window, but I do aim for one real meal each day within a window that is no more than 5 hours.  This is what I usually do, but I’m not psycho about it.  I want this to be a lifestyle that I adjust to suit me, rather than something that controls my life in a rigid manner.  It’s fine to open my window with a snack, and eat a meal later; or, I might choose to open my window with a meal and then eat a snack later.  Some days, I eat one meal only and that’s it.  I listen to my body, and on days that I am hungrier, I eat more.  On days when I am not as hungry, I eat less.  I don’t calculate calories, and I don’t restrict any foods—though I do pay attention to how certain foods make me feel. Now that I pay more attention to satiety signals (thanks, appetite and satiety hormones), my thoughts are no longer about how much food I can cram into a 5-hour window, which has made it
work much better for me.  I don’t even really track my window anymore—but when I do, I find that a 2-3 hour window is enough for most days.  If you had told me 5 years ago that I would be happily eating one real meal per day, and limiting all intake to a 2-3 hour window most days, I would have run screaming from the idea.  It sounds crazily restrictive!  In actuality, I have never had the peace around food that I have now.  I genuinely eat whatever I want every day, until I am full and satisfied. It feels too good to be true, but it IS true. One of the benefits of an intermittent fasting plan with a daily eating window is that it is easy to fall into a rhythm.  Your body learns to expect food at a certain time each day, and once you adjust to that schedule, it becomes easy.  In fact, I find it to be easier than eating all day long.  You don’t have to make any food decisions until your window opens.  No constant thoughts of “should I eat this now?” because when the window is closed, it’s closed.  I used to have many thoughts about eating during a typical day, and now I don’t.  It is so much more peaceful.  If you have never fasted before, that might sound unbelievable, but once you get used to it, it is such a great way to live. Notice that I mentioned in the previous paragraph how easy it is “once you adjust”.  I’m going to be honest with you here—the adjustment period can be the hardest part of implementing an intermittent fasting regimen, and it is why many people fail.  When you first start, your body is used to being in a fed-state during the day.  This means that your body is used to running off of your circulating blood glucose and stored glycogen for energy.  As soon as you run out of ready energy, your body sends a signal for you to eat, and you fuel back up with a snack, a meal, or that afternoon latte.  When you begin fasting, however, you don’t give in to those signals to eat, and your body can get MAD at you.  The signals to eat keep coming.  You might feel shaky, tired, or get a headache.  You may even feel a little sick to your stomach.  These feelings can be unpleasant, and if you eat, you’ll feel better immediately.  It’s the number one reason most people give me for being unwilling to try intermittent fasting:  they “can’t”, because they get headaches and “low blood sugar”.  This adjustment period is a barrier for many—but I want to encourage you to commit to a week or two before you decide that you “can’t” fast. Here’s the thing you need to remember:  your goal is to start burning your own fat for fuel.  The ONLY WAY to tap into that stored fat is to STOP running on glucose/glycogen.  You can either be a fat-burner or a sugar-burner.  The end.  Making the transition from a sugar-burner to a fat-burner is the hard part, but once you do it, you will be AMAZED at how good you feel.  I promise. Take today.  I’m writing this at 4:45 p.m.  I’m starting to get some mild hunger signals, because my body anticipates that I will break my fast within the next hour or two.  (No, I don’t start shoving food into my mouth as soon as 5:00 hits...anymore...though there have been days like that.)  Today I wrote for several hours, then went to visit some friends.  I jumped on the trampoline with their children. While there, I refused to eat some jellybeans that I was offered (apparently they might be delicious or they might be “booger” flavored...you can’t tell from looking at them...it’s some sort of fun surprise in every bite...thank goodness that fasting saved me from that fate.)  I ran a few errands and then came back home to more writing.  I haven’t felt tired or lethargic for one moment all day.  Contrast that with yesterday—which just happened to be Christmas Day.  Because intermittent fasting is flexible, I opened my window at noon with a Christmas brunch.  I was ready for a nap by 2 p.m., and I needed a cup of coffee mid-afternoon to keep me going.  Then I had to have a snack before dinner.  Then dinner.  Oof.  I thoroughly enjoyed my time with family, but I didn’t enjoy the way I felt after eating all of that food. The lesson that I want to share is this:  I feel better today, fasting, than I did yesterday, when I began eating at noon.  I didn’t have MORE energy from my frequent meals, and actually I had
profoundly LESS energy.  This is because it takes a surprising amount of energy to digest food, and I notice that whenever I open my window early in the day, I get a distinct afternoon slump.  When I’m fasting, I don’t get that slump.  Ever.  (In fact, one reason I gave up alternate day fasting, which I discuss in the next chapter, is that when I do a full fast over 24 hours in length, I can’t sleep at night— I have so much energy that it keeps me awake.) When you first start fasting, you will be stuck in that in-between transition period that I already mentioned.  Your body will yell at you to EAT, because it’s used to running on glucose/glycogen.  You are going to be grumpy.  Tired.  HANGRY .  Trust me—the promised-land is around the corner, once you make that transition to fat burning.  Once you get past the transition, you’ll wonder how you ever managed to eat all day long. There are several ways to make the transition easier.  One idea is to gradually shorten your eating window until you find a length that works for you.  Start with skipping breakfast.  Gradually push back your lunch time every day, until you are breaking your fast in the late afternoon.  This is a sensible approach that many people use when beginning an intermittent fasting lifestyle. Another way to make the transition easier involves a temporary change in WHAT you are eating during the day.  (Notice that I said it is temporary—I don’t restrict anything in my diet, and I am not going to ask you to do it, either.)  Years ago, in the 90s, I read a diet book called The Carbohydrate Addict’s Diet.  In this plan, you eat a low carb breakfast, a low carb lunch, and then for dinner you have a “reward meal” of whatever you want.  You must eat that reward meal in a time period that is one hour or shorter.  (In hindsight, I realize that the authors developed a type of intermittent fasting plan, well before the phrase “intermittent fasting” had been coined.) So, why is a temporary shift to a low carb eating plan for 2 of your meals helpful?  If you think back to the chapter on insulin and weight loss, you remember that when you have a lot of insulin circulating in your system, you won’t burn fat.  Fasting lowers insulin, but low carb diets also lower insulin (not as much as fasting, but enough to help you get started).  If you make sure that your low carb breakfast and lunch are “low carb/high fat”, also known as LCHF or Ketogenic-style (“Keto”) eating, it helps your body get into a fat burning state.  (Tip:  search the internet for some suggestions of what to eat for your LCHF/Ketogenic meals.  I could not eat that way forever, but remember—I am not asking you to, either.) You can use this strategy to smooth your transition to an intermittent fasting eating window.  Begin by having a LCHF breakfast and a LCHF lunch, plus a dinner of whatever you want, that you finish within a one-hour period to limit the length of time that you are releasing insulin (it ALWAYS comes back to insulin).  Soon you should be able to skip breakfast, and then eventually you’ll be able to painlessly skip lunch.  Voila!  You are an intermittent faster!  You’ll also find that it’s easier to skip breakfast and lunch than it is to prepare two LCHF meals.  Intermittent fasting...the diet for people too lazy to cook a bunch of meals during the day! I was never able to lose weight following the Carbohydrate Addict’s Diet, but temporarily eating LCHF during the day can really help your body through the adjustment period.  Don’t expect fast weight loss, but instead think of it as a stepping-stone to reaching your intermittent fasting window, as you become a fat-burner rather than a sugar-burner.  (Funny side note:  the author of The Carbohydrate Addict’s Diet, Dr. Racheal Heller, actually lost a great deal of weight and kept it off long-term, but she wasn’t following the plan in the diet book she released.  When you read her story, you see that what she did was skip breakfast and lunch every day, and then she ate dinner only.  It worked like a charm for her.  Remember though, this book was released during the 90s.  “Fasting” was not something that people were considering for weight loss.  Even though Dr. Heller lost her
weight by eating one meal per day, she developed a plan that had you eating the more typical pattern of breakfast, lunch, and dinner.  I assume it was because she felt that it would be an easier sell.) What if the idea of a daily eating window sounds too restrictive for you?  Good news—you may prefer an “up/down day” fasting strategy.  The next chapter will explain how those plans work.