As I already mentioned in the chapter on using an eating window approach to intermittent fasting, I started my intermittent fasting journey by using Dr. Bert Herring’s plan called Fast 5.  When I first started, I arranged my 5-hour daily eating window so I could maximize the number of eating opportunities in the day.  I was fasting for 19 hours each day, but I was eating 2 full meals during my window.  Of course, weight loss was s-l-o-w. Weight loss was so slow, in fact, that I experimented with some extreme calorie restriction within my 5-hour window.  You can read about that in my full weight loss story, which is in Appendix A. The extreme calorie restriction did speed up my rate of loss, but I was miserable.  This was also before I read any of Dr. Fung’s work on the dangers of prolonged calorie restriction, and before the Biggest Loser study was released.  Thankfully, I didn’t have the discipline to either count or restrict calories for long, so I didn’t do any long-term metabolic damage that I have been able to detect.  I do not recommend that you follow my example:  NO extreme calorie restriction for you! At that point, I re-read the Fast 5 book, and suddenly something jumped out at me.  Dr. Herring said, more than once, that during your 5-hour window, “you’re only eating one meal a day.”  That is a direct quote from his FAQ chapter, in fact. No wonder weight loss was so slow when I crammed in those 2 meals!  In late January of 2015, I started officially eating one meal a day with no conscious calorie restriction, and effortlessly reached my goal weight of 135 pounds by mid-March.  (I have gone on to lose a few more pounds since then.  How many?  I don’t know.  I no longer weigh myself. See the chapter on weighing to find out why!) After reaching my goal weight, I still wasn’t convinced that I wanted to fast every day.  Eating one meal a day worked, but did I really want to eat like that for the rest of my life?  At that point, I switched over to 5:2 for maintenance.  I used 5:2 from May-August to maintain my weight. I did full fasts of at least 36 hours for 2 days per week, and I ate normally for the other 5 days.  It worked like a charm. As you know, I am a teacher, so I was on summer break from the end of May-early August.  When school started back in August, I continued using 5:2; however, I suddenly had a problem.  I had to pack a lunch on my up days!  I realized that I didn’t WANT to pack a lunch.  Ever.  I also didn’t feel like eating breakfast before school.  It became crystal clear:  I am TOO LAZY for 5:2.  (Not really, but—okay—that is part of it.  I don’t want to have to think about breakfast or lunch when I’m working.  You can call me lazy if you want.  I don’t mind.) At that point, I thought back to my epiphany from March about eating one meal a day, and decided that was going to be my plan going forward.  I started a “one meal a day” Facebook group on August 24, 2015, with just me and my husband as members.  (He doesn’t do intermittent fasting—but I learned that you can’t start a group with just yourself, so I needed him in there to keep me company.) Eventually, I recruited some of my other intermittent fasting friends, and we began to form a community of people who realized that there is a great deal of freedom to be found in a one meal a day (OMAD) lifestyle.  As of December, 2016, we reached 3,500 members in our group, and the number is still climbing.  Many of the testimonials in Appendix D are from members of the OMAD Facebook group.  It’s the friendliest Facebook group I have ever been in, and the members are
extremely supportive of one another.  I guess that is because we have found a lifestyle that just WORKS!  No need to be grumpy or hangry when you have such a great weight loss/maintenance plan! Besides being a convenient plan for someone who doesn’t want to pack a lunch, like me, some research indicates that eating one meal a day has a metabolic advantage when compared to eating all meals spread out throughout the day. https://www.ncbi.nlm.nih.gov/pubmed/17413096  The study from that link is called “A Controlled Trial of Reduced Meal Frequency Without Caloric Restriction in Healthy, Normal-weight, Middle-aged Adults.”  The researchers found that subjects eating only one meal a day lost significantly more fat than those eating the same exact number of calories in a more-typical 3 meals per day pattern.  (Sorry, CI/CO, you lose AGAIN!)  If you think back to the two chapters on calories and insulin, this is just what we would expect to see happen. When you are fasting during the day, and keeping insulin low, you unlock your fat stores.  The body learns to burn fat preferentially for energy, and you become a fat burning machine!  Your body revs up your metabolism in response to the fast.  In contrast, when you try to eat frequently throughout the day, your body doesn’t dip into your fat stores as readily due to the frequent release of insulin.  If you are in any type of energy deficit, your body may burn muscle instead of fat (because your fat stores are locked away—thanks, insulin!) When fasting all day, you burn fat preferentially.  Amazing!  Then, you are able to eat a delicious meal of whatever you want for dinner.  Even if you eat 1,500-2,000 calories in your one meal, you’ll likely be in a caloric deficit.  No, I am not suggesting that you count calories, because I still believe that the practice of calorie counting is flawed and tedious.  I eat until I am satisfied, and I stop when I am full.  It is truly liberating.  I only mention it because it seems incredible that you can eat that much food in a meal and not GAIN weight. Here’s the thing, though.  I am pretty sure that I do not eat as many calories in my one meal as I would have eaten if I spread out my meals over the course of the day.  I am certain that I eat less when I follow a one meal a day lifestyle.  I have learned to listen to my satiety signals and I stop when I have had enough.  I don’t need to count calories or even worry about food intake.  Some days, I am hungrier, so I eat more.  Some days, I get full really fast, so I eat less.  I don’t worry about eating too much OR not eating enough, because when the body’s hormones are working properly, we naturally adjust intake to meet our body’s needs.  Think about it—animals in the wild don’t count calories, and they are not obese.  It’s only when we put animals on a feeding schedule that they develop weight problems.  (Think about all of the overweight pets, and compare them to animals in the wild, who effortlessly maintain their ideal weight.) One caveat—don’t expect your satiety signals to be perfectly in tune at first.  It takes awhile for your body to learn to listen to your hormones again.  You may even find that you tend to binge-eat for the first week or two.  Dr. Herring addresses this in his Fast 5 book, and calls it “compensatory overeating.”  Some people even GAIN weight at first, due to initial overeating.  Yikes!  Nothing makes a plan seem more terrible than sticking to it faithfully and actually GAINING weight.  Here’s the thing, though.  Once you spend a few weeks following an intermittent fasting lifestyle, your hormones get back into balance and you once again become in tune with your satiety signals.  You don’t need to count calories, just like the lean animals in the wild don’t have to count calories. I haven’t been specific about how long your window should be for you to be officially living the OMAD lifestyle.  I did that purposefully.  I am not going to tell you what your window length has to be.  So there.
If you eat one meal a day, and fast according to the recommendations in this book for a large portion of your day, you are living the OMAD lifestyle.  If you snack all day until dinner and only eat dinner, you are NOT living the OMAD lifestyle.  If you drink diet soda all day until dinner, and then eat dinner only, you are also NOT following the OMAD lifestyle.  You are on a calorie-restricted diet, because you are constantly spiking your insulin.  See the chapter on what you should consume during the fast for a specific list of what is or is not allowed.  If you aren’t following those recommendations, you are not fasting effectively, and I don’t want to hear about it when you experience a plateau or weight regain. The key to the OMAD lifestyle is that you are following the guidelines for fasting most of the day, and you are eating only one real meal most days.  That doesn’t mean that you have to limit yourself to one plate of food or eat within a one-hour window.  The last thing I want to do is shovel in food so I can meet some arbitrary deadline.  Once again, that is diet mentality, and not a pleasant lifestyle.  I no longer time my eating window most days, and it is an incredibly freeing way to live. Let’s see how this could look.  What if I drink black coffee and water until 4 p.m., and then I eat a snack at 4.  I eat dinner at 7 p.m., and then I eat dessert at 8 p.m., at which time I close my eating window, because I am satisfied.  Did I follow a one meal a day lifestyle?  I hope you said yes, because that is a perfect example of the flexibility you have when following OMAD.  It was one real meal, plus a snack, plus dessert, all within a 4 hour time period. On another day I might eat dinner at 6 p.m., and by 6:30 I am full and satisfied.  Is that OMAD? Why, yes, it is!  Am I practicing calorie restriction?  NO, because I am full and satisfied.  My hormones told me I had enough that day. For me, the OMAD intermittent fasting lifestyle is incredibly flexible.  I have learned to listen to my body, and on days where I am hungrier, I will have a longer eating window.  On days when I am less hungry, I eat a smaller meal.  It feels like a lifestyle rather than a diet, because I am not controlled by a bunch of rules.  If I have a special occasion that includes brunch, I will eat more than one meal that day, and it’s okay—because in a lifestyle, every day doesn’t have to be perfect (because this isn’t a religion.) Are you ready for a trick question?  What about this:  if I eat brunch at 11:00 a.m., and then dinner at 6:00 p.m., did I follow OMAD?  The answer is NO.  Remember, though—it is okay to deviate for a special occasion every now and then.  I didn’t cheat—I had a planned indulgence.  I don’t do that often, so it is fine.  I am still living the OMAD lifestyle.  It isn’t a jail sentence, it’s a lifestyle. If you are following the OMAD lifestyle to lose weight, you probably don’t want to be quite as flexible with your window length or planned indulgences as I am in maintenance.  When I was in weight loss mode, I did generally stick to an eating window of about an hour many days.  I also didn’t include dessert as often.  Intermittent fasting has many advantages over regular diets, but it isn’t magic.  It is possible to have such a luxurious window that you will stop losing weight, or even gain weight.  This is where you have to be honest with yourself.  You can’t have seven snacks, dessert, and one huge meal and expect great results.  Sorry. The good news is that when I follow the OMAD lifestyle consistently, fasting properly during the day, and eating only one real meal each evening, my satiety signals are pretty strong, and I don’t overeat often.  Last night I didn’t eat dessert, because I didn’t want it!  I was literally too full to eat cake! As I already mentioned, Dr. Herring (of Fast 5) wrote a second book that I highly recommend, and it is called Appetite Correction. Appetite Correction is the Holy Grail of intermittent fasting, and it is the state you reach when your satiety signals are in tune with an appropriate amount of food for your
body.  The OMAD lifestyle gives me fantastic AC, which is why it is so easy for me to follow.  I highly encourage you to experiment with various window lengths or fasting approaches until you find AC.