Intermittent fasting has been getting a lot of buzz lately. You may have heard of it referred to as intermittent calorie restriction, alternate-day fasting, or time-restricted feeding. And you may have heard that it’s good for weight loss, diabetes and other health issues.

Intermittent fasting has become increasingly popular in recent years, and for good reason. Many people find it easier to make the time to eat less during the day, and many people are more inclined to stick to their diet plan when eating less is easier.

Research has shown that eating within an 8-hour time-limit on a daily basis can help with weight loss, increase your metabolism and boost your overall health. However, the real question is, “Why do we need to cut down on calories when we’re already burning them?” Some people might find intermittent fasting to be a challenge to get used to, but when practiced correctly, this dietary approach can help you lose weight and keep it off.. Read more about what to eat during intermittent fasting and let us know what you think.

Chapter 2

The Basics of Intermittent Fasting

What does “intermittent fasting” entail? Why is it that so many people are doing it? Let’s start with the basics, which include definitions of important terminology, a rundown of the most common intermittent fasting regimens, and some unexpected facts regarding intermittent fasting that you won’t find anywhere else.

Important ideas

  • When you fast intermittently, you eat when you want and don’t when you don’t. However, each fasting plan differs in terms of when and how much you consume (or don’t eat).
  • Some individuals define intermittent fasting more narrowly than we do. Under the banner of intermittent fasting, we’ve included intermittent energy restriction (such as the 5:2 diet), time limited eating (such as the 16:8 and 20:4 diets), and fasting imitating diets in this booklet.
  • Intermittent fasting has many advantages. However, not everyone benefits equally.

What is intermittent fasting, and how does it work? 

In some respects, the idea of intermittent fasting (IF) is so basic that reading a multi-chapter booklet on the subject seems pointless.

Fasting is simply a fancy way of saying “I’m not eating.”

The word “intermittent” implies “once in a while,” “sometimes,” or “now and then.”

When you put the two together in a sentence, you’re essentially saying:

You have to fast now and then. You eat at other times.

Except that IF is a little more complicated than that.

When is the best time to eat? And how much is it? When it comes to fasting, how long should you go? How do you maintain your consistency?

Those questions will be addressed later in the ebook. For the time being, we’d like to provide some context:

Let us begin with a few definitions.

Your cheat sheet for vocabulary

Here’s a glossary of some of the words we’ll be using in this book.

  • Intermittent fasting (IF) is when you consume nothing for a period of time.
  • IER stands for intermittent energy restriction, which means eating a lot less (but not nothing) on some days and eating regularly on others.
  • FMD: Fasting Mimicking Diets: One week of the month, eat approximately half as much as normal.
  • ADF stands for alternate day fasting, which is alternating days of eating with fasting or eating much less.
  • TRF: Time-restricted feeding: Eating only within a pre-determined window of time (or “eating window”).
  • Caloric restriction (CR) is defined as consuming fewer calories than you burn.

Intermittent fasting is a kind of intermittent fasting that is described as a period of

Intermittent fasting (IF) is the word used by some nutritionists to describe the practice of eating nothing or a lot less than normal for prolonged periods of time.

And there are four primary methods for doing so.

  • Classic IF: You eat nothing every now and again. On an Alternate Day Fast, for example, you would fast every other day. Other IF plans call for fasting only one or two days per week, or a couple (or more) times per month.
  • Intermittent energy restriction, often known as “partial fasting,” involves consuming fewer calories but not none. On the 5:2 diet, for example, you would eat normally five days a week and limit calories two days a week.
  • Time-restricted feeding: You limit your meals to a certain amount of time, known as a “eating window.” On the 16:8 diet, for example, you eat for 8 hours a day and fast for the other 16. The 20:4 diet only allows you to eat for 4 hours each day. This kind of fasting also includes traditional meal skipping.
  • Fasting-like diets include eating approximately half as much as normal for a week. After that, you eat regularly for 3-4 weeks before restarting the cycle.

Fasting is described as going without eating for at least 8 hours in technical terms. Some of the fasting techniques listed above involve 8-hour (or longer) fasts, while others do not.

However, we’ve grouped all of those choices under the IF umbrella in this booklet.

We’ll use the word IF to refer to all of these eating patterns unless otherwise specified for clarity.

A short history of intermittent fasting

Humans have gone without food since the dawn of humanity on our planet, sometimes deliberately and sometimes unintentionally.

Many cultures throughout the globe have suffered some kind of IF, which continues to this day. When food is abundant, they eat a lot, and when food is limited, they eat very little or none at all. Many individuals go hungry for economic reasons even in developed nations.

Humans have fasted on purpose in addition to times of scarcity:

  • Plato and Pythagorus, for example, went without meals on occasion because they thought it improved their health and mental efficiency. 1
  • During Ramadan, Muslims fast from sunrise until sunset. On Yom Kippur, Jews do it to atone for their sins. During the 40 days of Lent, Christians have also been known to go without a variety of meals in a partial fast.
  • Gandhi staged 17 hunger strikes in response to the British government’s prejudice.

Researchers didn’t start experimenting with what, how much, and how frequently they fed their lab mice and rats until the 1900s. The controls were some fortunate rats that had access to food 24 hours a day, seven days a week. Others were in a far worse situation. Researchers placed them on a rigorous diet that most people would find difficult to stick to.

As a consequence, the slightly malnourished rats lived longer. 2

Lab rats and mice have fed just once a day, every other day, or only at particular periods of the day throughout the years in the name of research. The rats become healthier as a result of these fasts, which protect their brains, prevent cancer, and delay the aging process. 3

Medical experts started experimenting with a variety of fasting methods to improve health, lifespan, and weight reduction in humans in order to help them enjoy the same advantages. Those methods were just ruthless.

Eventually, scientists realized that most people can’t adhere to a diet that requires them to go without food for weeks at a time.

As a result, they devised milder, more long-term solutions, such as fasting one or two days each week.

According to new study, when done correctly, IF may help:

  • Control blood glucose levels 4
  • Control lipids in the blood, such as cholesterol 5
  • Reduce your chances of getting heart disease, cancer, and other diseases6,7
  • Maintain a healthy body weight 8

(In Chapters 4 and 5, you’ll learn more about these advantages.)

3 facts regarding intermittent fasting that you probably don’t know

Although IF has many advantages, there are certain instances where it falls short. We know: based on our own experience with a variety of IF regimens, the experiences of our customers, and the most recent research:

A little fasting may make a big difference.

We discovered that intermittent fasting isn’t always quicker or better than traditional calorie restriction. Surprisingly, we discovered that a little amount of fasting (one day a week) may provide more benefits than a large amount of fasting (two or more days a week).

In fact, when co-founder John Berardi, PhD, and director of curriculum Krista Scott-Dixon, PhD, went too far with fasting, they were less healthy.

You are not required to stick to a strict schedule.

Exact time, quantities, and schedules… These aren’t as important as “getting it in the ballpark” or adhering to the fundamental principles that make fasting and other disciplines effective.

This is particularly true if your nutritional status is poor (which is most people).

There is no one-size-fits-all solution.

Because of the following factors, people’s experiences with IF may vary greatly:

  • variations in physiological characteristics such as age, sex, or health
  • psychological differences such as people’s willingness to put up with discomfort now in order to gain later
  • Social support or living in a food-focused society are examples of environmental variations.

Don’t be caught in and begin practicing IF haphazardly or erratically in the hopes of a Cinderella-like life change.

Instead, put assertions to the test, delve into the research, grasp the fundamental processes, and take a cautious, evidence-based approach.

We’ll show you how if you keep reading.


To see the information sources mentioned in this article, go here.

  1. PR Kerndt, JL Naughton, CE Driscoll, and DA Loxterkamp. The history, pathophysiology, and problems of fasting. Nov 1982;137(5):379–99 in West J Med.
  2. RB McDonald, JJ Ramsey Clive McCay and 75 years of calorie restriction research are honored. 140(7):1205–10. J Nutr. 2010 Jul;140(7):1205–10.
  3. TL Jensen, MK Kiersgaard, DB Srensen, LF Mikkelsen. Lab Anim. 2013 Oct;47(4):225–40. Fasting of mice: a review.
  4. R. Antoni, K.L. Johnston, A.L. Collins, and M.D. Robertson. Differential effects of intermittent vs. continuous calorie restriction on postprandial glucose and lipid metabolism in overweight/obese individuals after matched weight reduction. 119: 507–516 in Br J Nutr.
  5. R. Antoni, K.L. Johnston, A.L. Collins, and M.D. Robertson. Intermittent fasting’s effects on glucose and lipid metabolism. 361–368 in Proc Nutr Soc, 2017.
  6. M-P St-Onge, J. Ard, M. L. Baskin, S. E. Chiuve, H. M. Johnson, P. Kris-Etherton, et al. A scientific statement from the American Heart Association on meal time and frequency: Implications for cardiovascular disease prevention. Circulation 135: e96–e121, 2017.
  7. Weight cycling and cancer: evaluating the evidence of intermittent calorie restriction and cancer risk. Thompson HJ, McTiernan A. Cancer Preventive Research, vol. 4, no. 4, 2011, pp. 1736–1742.
  8. SD Anton, K Moehl, WT Donahoo, K Marosi, SA Lee, AG 3rd Mainous, et al. Understanding and utilizing the health advantages of fasting is known as “flipping the metabolic switch.” Obesity. 254–268 in Wiley Online Library, 2018.

Intermittent fasting is a type of dietary restriction that allows you to eat normally for a portion of the day, and then follow a portion of your usual eating pattern for a different portion of the day. Not only does restricting food this way allow you to eat all the nutritional value of your regular meals, it also helps to keep you from overeating by making sure you don’t overeat at your normal eating time.. Read more about is intermittent fasting healthy and let us know what you think.

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