Intermittent Fasting: The Complete Guide You Need

Updated May 27, 2021 by Iulian Ionescu | Read Time min.
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You’ve probably heard about intermittent fasting so long as you don’t live under a rock. It’s a popular term thrown around by news media, celebrities, your mom, and the guy who sells you your morning coffee. But what does it do? Is it merely eating fewer calories, which results in weight loss, or is there something more to it? I’ve been using a variety of intermittent fasting forms for the past three years. I’ve seen results with my own eyes, and, whereas I cannot yet vouch for all the long-term benefits, such as ten plus years, I can speak to what it did to me in the short term. From there, I’ll give you a ten-step process you can apply today to start intermittent fasting safely and effectively.

What Is Intermittent Fasting?

If you look up the official definition of the word “fasting,” you’ll find it in the Oxford Dictionary defined as “a period during which you do not eat food, especially for religious or health reasons.

Bah. It sounds freaking terrible. But the definition itself is entirely accurate at its basic level. It’s what it leaves out that makes people wary. The truth is we all cringe when we hear about not eating. After all, since birth, our parents and grandparents shoved food in our mouths, sparing no moment to let us know how we would die without it.

So, the thought of not eating, even for a short period, is quite disturbing to most people. However, we do it all the time—all of us.

Every night when you go to sleep, your body begins fasting. True to the definition, sleep is the period in which you do not eat. If you sleep for 12 hours, you fast for 12 hours. Let’s ignore for now the rare cases of fridge sleepwalkers and middle-of-the-night snackers. If you’re one of those, you’ll need some more work on your self-discipline.

Instead, let’s focus on the average person’s diet, which usually involves three to four meals per day with several snacks in between. How do you leap from that to fasting?

“Periodic fasting can help clear up the mind and strengthen the body and the spirit.”Ezra Taft Benson

fasting food control

Is Fasting Dangerous?

Before we move on, let’s answer this question which I believe you have on the tip of your tongue: Will intermittent fasting damage me?

The short answer is no, but here are some more details.

First, as I demonstrated above, it’s not that crazy not to eat for 12 hours; you do it every time you sleep. The average human body can store anywhere between 80,000 to 100,000 calories. That means that, at an approximate 2000 calories per day, you have enough energy stored in your body to survive for forty to fifty days.

That is, of course, an extreme, and I am only emphasizing it to shatter those concerns you may have had when you first read about fasting.

When you add “intermittent” to fasting, you are merely saying that you will be fasting intermittently. Therefore, you will eat for a certain period, then you’ll stop eating, and later, you will resume.

Sound familiar? Of course, it does. You’re already doing that, too. You’ve been intermittent fasting your entire life.

The period between lunch and dinner is intermittent fasting. So is your sleep or the time between breakfast and lunch. Now, before you get all giddy, intermittent fasting done for weight loss and wellness is quite more scientific than that, as we will discuss throughout the rest of this article. The process involves lengthening the periods between meals, reducing the number of meals within 24 hours, and improving the quality of the meals.

But for now, if you remember anything, let that not be the dictionary’s original definition. Think of intermittent fasting as timing your food intake and shortening your feeding window to maximize weight loss and health benefits. Next, let’s see how it works.

What Intermittent Fasting Did for Me?

I started my intermittent fasting journey in mid-year 2018. I’ve been experimenting with the ketogenic diet at the time, and I had already seen significant results. When I started that journey, I was about 193 pounds and wasn’t happy. I wasn’t satisfied with my body, my athletic performance, and I suffered from a slew of ailments, including high blood pressure and acid reflux.

After implementing intermittent fasting in my day-to-day and converting slowly from a more traditional ketogenic diet to a modified slow-carb type of diet, here are my results:

My Intermittent Fasting Results

  • Weight dropped from 193 lb. to 174 lb., then finally set at 180 lb.
  • Body fat % reduced from 25%+ to about 16%
  • Blood pressure regulated from about 149/92 to 130/70
  • Acid reflux and daily nausea subsided and eventually disappeared

While experimenting with intermittent fasting, I continued my exercise regimen using workout videos and running. I noticed an increase in my stamina, flexibility, and overall performance. Soon, I learned how to optimize my food intake, so it correlated with my exercise, rest, and sleep.

In addition, I used to be constantly congested during the colder months. My nose would be stuffy, and I’d have to use nose drops several times per night to be able to breathe. About a year after doing intermittent fasting consistently, I noticed a significant reduction in that respiratory inflammation up to the point where I finally gave up those nose drops for good. My sleep quality improved, and I haven’t gotten a severe cold since.

So intermittent fasting not only worked, but it has transformed me, and it continues to do so three-plus years later.

“The light of the world will illuminate within you when you fast and purify yourself.”Mahatma Gandhi

healthy food diet

Intermittent Fasting Brief History

Hippocrates, known as the father of medicine, once said that “to eat when you are sick is to feed your sickness.” Although my grandma would frown at that statement, time and practice have proven its validity.

Hippocrates lived in 460 BC, so the idea of food restriction to allow for the body’s natural reconstruction and rejuvenation is not new.

About 500 years ago, so much closer to our time, German-Swiss doctor Philippus Paracelsus wrote that “fasting is the greatest remedy—the physician within.”

Another ancient Greek writer and historian wrote, “instead of using medicine, better fast today.”

The Greeks noticed how most animals stop eating when they’re sick and began to analyze what food restriction does to the body. They concluded that restricting food was an instinct that fired up the body’s healing mechanism. Also, they believed that fasting improved cognitive functions and abilities. They asserted that food intake caused blood to flood the digestive system to cope with the intake, leaving less blood for the brain.

Even Benjamin Franklin, whose credentials we don’t need to address, wrote that the “best of all medicines is fasting and resting.”

In addition to this, all religions and cultures have developed different yet similar fasting systems. Fasting was never considered a harmful behavior but an enlightening one. It’s regarded as a cleansing mechanism that is beneficial to the body and the spirit.

In more modern times, therapeutic intermittent fasting was introduced around 1915 to treat obesity. Later, in the 1960s and the 1970s, scientific research accelerated, and enthusiasm about intermittent fasting blossomed in the news, magazines, and among celebrities.

Today, there are dozens of sites and books on intermittent fasting and intermittent fasting benefits, so it’s no surprise that people now suffer from information overload. It’s hard to distinguish the good from the bad.

Before we get there, let’s first look at some of the most popular intermittent fasting methods in use today.

“To lengthen thy life, lessen thy meals.”Benjamin Franklin

Types of Intermittent Fasting


The 16/8 Method

intermittent fasting 16/8 method

One of the most widely used intermittent fasting methods is known as the 16/8 method. This system implies a fast (as in no food) for 16 hours, followed by a “feeding window” of 8 hours, hence 16/8. During those 8 hours, you are supposed to eat all the calories your body needs for the next 24 hours.

The reason why 16 is a significant value will become apparent when you read the next section explaining the five stages of intermittent fasting.

There are several variations of this method; among the most popular ones are 18/6 and 12/12. In the end, you can combine any number of hours to create a fasting window followed by an eating window, but the fasting window should be at least 12 hours.


The 5/2 Method

intermittent fasting 5:2 method

The 5/2 method became very popular in the UK around 2012 and popularized by British journalist Michael Mosley. This method implies eating a regular diet for five days a week, while on the other two days, you limit your food intake to one meal of 500 to 600 calories.

Basically, you are doing two days of fasting and eating normally for the other five days. In my opinion, this method is more challenging to maintain because the emphasis and the pressure will be exclusively on those two days. I feel like you’d be much more likely to cheat.

That being said, the 5:2 system does work, and it’s not a bad idea to use it as a start.


Eat Stop Eat

intermittent fasting eat-stop-eat method

The Eat Stop Eat method is like 5:2 in the sense that you don’t consume any food for two non-consecutive days of the week. Therefore, you do two days of 24 hours fast and follow a regular diet for the remainder of the week. As you can imagine, the calorie intake is even lower than during the 5:2 diet.

Again, I am having a bit of an issue with this method. Unless you keep in check during the non-fasting days, there is the possibility of over-eating during those windows and canceling the positive effects of the 24 hours fast.


Alternate Day

intermittent fasting alternate day method

The alternate-day fasting method takes bits and pieces from all the methods above and makes them more consistent. During this fasting type, you will do a 24 hour fast one day and eat a regular diet the next day. A less intensive system involves eating just a limited number of calories during the fasting day.

Unlike 5:2 and Eat Stop Eat, I feel like alternate-day fasting emphasizes consistency more than anything else, and I believe it to be a superior method.

I believe that it’s rather tricky for a beginner to do a 24 hour fast every other day, so I don’t recommend it as a starting point.



intermittent fasting OMAD method

OMAD stands for one meal a day. As you probably figured by now, the OMAD diet involves fasting for about 23 hours every day, then use the last hour to consume a single meal. That one meal must provide all the nutrients and calories your body needs for the next 23 hours of fast to come.

OMAD is a strict fasting system and might prove challenging for someone who is social and likes to be in social settings. Because you restrict food intake to the one-meal window, you may have difficulty maintaining it for long periods.


What works for you

As you can see, there’s a variety of methods to choose from. You need to experiment and try them out to see which one is best for you and bring you the most results. I recommend the following progression:

  1. 12/12 — three weeks
  2. 16/8 — three weeks
  3. 18/6 — six weeks
  4. 18/6 with one day per week of 24-hour fasting — three weeks
  5. 18/6 with two days per week of 24-hour fasting (not consecutive) — three weeks
  6. From here on, you’ll be able to use any method because you will be ready.
“In a fast, the body tears down its defective parts and then builds anew when eating is resumed.”Herbert M. Shelton

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The Six Stages of Intermittent Fasting

Now let’s look at what happens to your body after you’ve taken your last food bite.

After 12 hours

After 12 hours since the last meal, your body enters a metabolic state known as ketosis. During this period, your body begins to break down fat, and the liver uses some of that fat to produce ketone bodies which serve energy to all parts of your body. During this time, the ketone bodies replace glucose as an energy source for your heart, brain, and the rest of your organs.

Note that this doesn’t mean that you are doing a ketogenic diet just because your body produces ketones. The ketogenic diet involves being in ketosis continually, while intermittent fasting doesn’t require that, although using them in combination is extremely powerful.

Unfortunately, in a regular Western diet, most people don’t get to a ketosis state. Because of late-night eating or snacking followed by an early breakfast, the ordinary folk won’t allow the body to go for 12 hours without food, thus preventing the ketosis benefits from ever occurring.

Shortly after the 12-hour mark, the production of HGH (Human Growth Hormone) starts to increase. Although it sounds like something a body-builder would take as a supplement, it’s not. HGH is a vital hormone that our bodies produce that stimulates cell reproduction, cell regeneration, and growth. Therefore, it’s an essential ingredient to maintaining lean muscle during periods of fasting.

After 18 hours

At the 18-hour mark, your body switches to a more aggressive fat-burning mode. That means that now there’s significant production of ketone bodies. Your body is pulling fat out of your tissues to convert it to ketones and use those ketones to deliver energy to your organs.

More so, the ketones now act as a signaling molecule telling your body to begin repairing DNA structures and reduce inflammation.

That is the reason why the 16/8 and its more advanced version, 18/6, work so well. It’s because, for 4 to 6 hours, you maintain your body in this state where most fat burning occurs and inflammation reduces.

After 24 hours

At the end of 24 hours, your body finishes what is known as the post-absorptive stage. All the food in your system has been metabolized, and glucose levels have dropped to a minimum. Insulin secretion stops. During the full 24 hours, your body has used all the stored glycogen in your muscles and liver. Typically, we reserve about 2000 calories worth of glycogen, so after 24 hours, that storage is depleted.

As you reach the 24-hour mark, a process known as autophagy begins. Autophagy is a natural process of cell regeneration. During this time, the body can focus on self-cleaning by finding damaged cells and reusing their components to generate new, healthy cells.

Autophagy is one of the most critical parts of intermittent fasting. Scientific research has shown that autophagy helps slow down aging and prevent the effects of several diseases, such as Parkinson’s, Alzheimer’s, and cancer.

That is also why I recommend at least one day per week of a 24-hour fast.

Here is a comprehensive infographic describing these stages with some more details on the timing.

intermittent fasting stages
Source: Lybrate

Intermittent Fasting and Weight Loss

One of the first reasons why people take on intermittent fasting is for weight management. When it comes to weight loss, few things work as well as intermittent fasting, and that’s for two reasons.

A) Caloric deficit—No matter how you look at it when you ingest fewer calories than your body burns, you will lose weight or, at least, you won’t gain any if that difference is minimal. Because of the feeding window restriction, you will simply not eat as many calories as you would if you were eating throughout the day. You’ll find yourself barely scratching the 1500-1800 calorie mark, as opposed to 2500 or more. Applied consistently, this will significantly reduce the amount of calorie intake and will have powerful effects on your weight.

B) Fat burning—As your body switches from glucose to ketones for energy, fat is pulled out of your tissues to create energy, thus lowering the amount of fat stored in your body. That is precisely the opposite of what happens when your body is high on insulin throughout the day, and fat is being deposited in your tissue. The longer you fast, the more fat is pulled out of your body and used to generate energy.

To benefit fully from weight loss during intermittent fasting, I highly recommend implementing an exercise regimen to go along with it.

Because exercise forces the body to use glucose first to power up the muscles, a workout during your fasting state will accelerate that process. You will deplete your body of carbs and, therefore, glucose, allowing the other functions—ketosis and autophagy—to start and last longer.

Even if your goal is not to bulk up on muscles, I highly recommend a weight-based exercise at least once or twice per week.

healthy food calories

How to Implement Intermittent Fasting in 10 Steps

Here are ten steps you can take to implement intermittent fasting safely and efficiently in your life.


Clean up your nutrition.

First and foremost, make a list of what you should and should not eat. Intermittent fasting won’t shield you from the effects of inadequate nutrition. Clean up your pantry, remove bad foods, and stockpile healthy ones.

That depends a lot on the lifestyle you want to lead. Vegetarian? Vegan? Keto? Paleo? Whatever it is, make sure it’s clean. Because you will eat less food at any given time, each meal must carry all the necessary vitamins, minerals, and fiber your body needs.

At the start, you should also do a full panel blood test to identify if you need to take any supplements, such as Vitamin D or potassium, which are usually on the lowers side in most people.


Understand and be clear about the cycles in your life.

You probably have a job and, maybe, kids. You might be going to school or do both. Whatever it is, you must take the time to put your regular weekday and weekend day on a calendar and understand when you wake up, when you go to bed, and what you do during the day. That allows you to align your intermittent fasting period with your sleeping period and time your exercise with breaking your fast.

Intermittent fasting must become a part of your lifestyle and not an annoyance that you must “cope” with.


Establish your intermittent fasting weekly schedule.

Using the schedule from point 2) and the various types of intermittent fasting presented above, design your week ahead of time. Please don’t leave it up to chance or how you feel. Your schedule must drive it, not your feelings. As a beginner, I suggest starting with a few days a week and then working your way up week by week until you can fast every day.

Consistency and discipline are paramount here, especially at the beginning when you are prone to temptations.


Identify one or two days for your most prolonged fasts.

We all have one or two days per week where things are prone to get a bit out of hand. For most, it’s the weekend. Therefore, choose one day, either before or after the weekend, when you do a longer fast, such as 24 hours.


Time and stick to your exercise routines.

It’s imperative to keep physically active regardless of the type of nutrition you have. Exercise works incredibly well together with intermittent fasting. Time your workouts toward the end of your fasting window; even better—right before you break your fast. That will generate the most benefits and will accelerate your results.


Read and learn about what breaks your fast.

There will be temptations many a time during your intermittent fasting periods, especially in the beginning. Most people will wonder, will this break my fast?

The answer is easy: does it have calories? If yes, then yes, it will break your fast, and it doesn’t matter if it’s liquid or solid.

But there are a few things that you can ingest during your fasting period, and some of them will help you go through the fasting window easier. I’ve put below a video from Dr. Berg where he explains what doesn’t break your fast.


Learn and practice breaking fast safely.

When you reach the end of your fasting window, why do you eat? Can you eat anything and in any quantity. Technically, yes, but should you? Definitely not.

To prevent bloating and other stomach issues and maximize intermittent fasting’s health benefits, try to follow the established practices of breaking your fast.

One of the best ways I’ve used is breaking the fast with bone broth and apple cider vinegar. I know bone broth sounds gross, but believe me, the latest products on the market are designed specifically for this purpose, and they taste great. I recommend watching the video below on how to break your fast by Thomas Delauer.


Be patient.

You are not going to see significant results for at least six weeks, sometimes more. You might even experience opposite effects for the first 90 days as your body rebels against the changes. That’s normal, so don’t get discouraged. Intermittent fasting is not a quick fix. Instead, it’s a long-term commitment, and it needs to be regarded in that way.

Make your schedule and stick to it. Believe in the results and don’t stop.


Reward yourself.

Although I don’t particularly recommend counting calories, if you do, you’ll notice that you are consuming fewer calories on a weekly average than during a regular diet when you are on intermittent fasting.

That means that you have a calorie deficit every week. Now and then, reward yourself. Eat your favorite dessert or whatever meal you crave. Then, get back on track. However, be careful if you are on specific diets, such as the keto-make sure you only cheat with approved cheat meals.


Reevaluate your health goals.

Every six months, take stock of where you are, what you have accomplished to date, and what your goals are for the next six months. At least once per year, visit your primary doctor and have a full blood and urine test.

Analyze your test results with your doctor to make sure that you are on the right track. That is very important because intermittent fasting will affect changes to your blood pressure, cholesterol, triglyceride levels, and many others.

Although intermittent fasting usually improves these values, it’s critical to validate this for yourself with annual blood results and identify if you need to take additional supplements such as vitamins, minerals, or protein.

healthy food eating

Intermittent Fasting Benefits are Undeniable

I hope I managed to instill at least some curiosity in you about intermittent fasting. I know you are reluctant. I’ve been that way for over thirty years. I remember people in my family fasting for 30 days before Easter and thinking they were crazy. Even removing meat on Friday seemed insane.

It’s clear now that I lacked the knowledge about the science behind food and our feeding cycles, but I also had weak self-discipline and a complete lack of self-awareness.

I recommend you try intermittent fasting for a while; as I said above, 90 days or more is an excellent way to gauge if it works for you. I guarantee that you will see results, and those results will get you excited to do even more.

Intermittent fasting is just one way of getting healthy and in better shape, but it benefits from attacking your weaknesses and forcing you to become disciplined and care about health and wellness.

With this, I am going to break my fast! Oh wait, I must exercise first…

What will you do?

Other Intermittent Fasting Resources

Now, before you go, I have…

3 Questions For You

  1. What has prevented you from trying intermittent fasting in the past?
  2. What is your personal experience with timing food and restrict food intake?
  3. Do you have any specific issues that have turned you off from intermittent fasting once you tried it?

Please share your answers in the comments below. Sharing knowledge helps us all improve and get better!



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