How Does Intermittent Fasting Work? : 3 Different Protocols

A clock on a plate to show that intermittent fasting is about your meal timings and frequency.

During the past several years intermittent fasting has gained popularity. Is this popularity grounded in reason? Or is it just hype? In this article, I’ll be answering the question, how does intermittent fasting work?.

What Is Intermittent Fasting?

Intermittent fasting is simply a term for a pattern of eating that you alternate between eating and not eating (fasting). That is to say periods of fasting and periods of not fasting.

There are many different approaches to intermittent fasting but I’m only going to elaborate on the most practical ones. The ones that I think will be of the most utility to you.

But before I get on to that, lets bust 5 common myths about intermittent fasting that are not based on truth.

6 Common Intermittent Fasting Myths – How Does Intermittent Fasting Work?

Here are some of the 5 common myths about intermittent fasting that are based on conventional dieting dogma. These entrenched beliefs just aren’t true. And I’ll tell you exactly why. So let’s get on to the first myth.

Myth 1- Eating Smaller Meals Speeds Up Your Metabolic Rate (Metabolism) So That You Burn More Calories

Due to something called the thermic effect of food (TEF) Your body uses a percentage of the calories you eat to actually burn, digest, absorb and dispose of the food you consume. For further explanation on the thermic effect of food look at the graphic below.

Energy balance and the thermic effect of food and how it relates to intermittent fasting

If you eat 2000 calories of food in 6 meals in comparison to 2000 calories in 2 meals from exactly the same foods. You’ll burn the same amount of calories from the thermic effect of those foods. You won’t burn more calories or “stoke the metabolic fire” just because you’re eating more meals. All calories being equal.

The only way you could burn more calories through the thermic effect of food is if you ate more calories. But the more calories you eat that results in you going over your total daily energy expenditure (TDEE) (The number of calories you burn every day). The more fat you will put on.

So to put it simply, eating more meals doesn’t make you burn more calories or increase your metabolic rate and stoke the metabolic fire. And if you do eat more calories than you need to, yes this will result in more calories burned from TEF, but that will be negated by the fact you’ve gained fat from going over your calories.

Myth 2 – If You Do Intermittent Fasting ( Don’t Eat For An Extended Period Of Time) You Will Lose Muscle

The amino acids from protein can be absorbed into your bloodstream for up to 24hours after eating them ( A high protein meal with starchy carbs and vegetables). Depending on the type of protein that you eat and the other types of foods you eat with it. The fact is as long as you consume enough daily protein and calories, (depending on your goals) that’s all that matters. Regardless of meal frequency and extended periods of fasting throughout the day.

For instance, one study examined the effect of eating a significant amount of protein ( a whole days worth of protein) followed by a 20 hour fast and found that this didn’t negatively impact muscle retention.

This proves the fact that you won’t lose muscle during intermittent fasting. As long as adequate protein intake is met. Especially if you use the most popular and in my opinion the most enjoyable type of intermittent fasting the 16:8 intermittent fasting protocol popularized by Martin Berkhan at

Myth 3- You Need To Eat Before Working Out, Otherwise, You’ll Have Crappy Workouts

I held this belief for a while but it wasn’t until I read the lean gains method(Which I highly encourage you to read) until I witnessed that you can gain muscle and strength training fasted ( I only had one scoop of whey protein before training) My bench press, squat and deadlift increased while training almost entirely fasted if you disregard the protein shake.

Myth 4- Breakfast Is The Most Important Meal Of The Day- Skipping Breakfast Is Bad For Your Health

The fact is if you eat a healthy diet full of whole foods such as grains, fruits, vegetables, lean meats, and legumes and you eat the right amount of calories for you and your goals. It really doesn’t matter if you fast and miss breakfast or not.

Researchers and scientists have proven that the law of energy balance works and can’t be denied. No matter if you eat breakfast or not.

The bottom line is it really doesn’t matter when you eat as long as you’re eating healthy foods and are eating the right amount for you. Some people follow the one meal per day diet and still get good results.

Skipping Breakfast And Eating A Couple Of Larger Meals Before Bed Can Leave You Going To Bed Full And Satiated

This is one of my experiences. If I skip breakfast and save my calories for later on in the day. I actually have an easier time staying full before bed. The fact is skipping breakfast is not harmful to your health. Severely undereating can be. But If you know how many calories you need to consume every day. Then skipping breakfast allows you to have bigger meals later on in the day. Which from my experience can lead to better dietary adherence. Especially in a calorie deficit, if done correctly.

Myth 5 – If You Eat Carbs After 8PM Your Body Stores them As Fat

Specific fasting approaches, such as the 16:8 lean gains method. You generally fast from 8-10 pm to 12-2 pm. Or if you try a different fasting approach, like the eat stop eat method you fast for 24 hours once or twice per week. The rest of the time you eat using a normal eating schedule. And one thing they all have in common is that they don’t forbid you from eating carbs after 8 pm.

This is because fasting is just a meal timing/ frequency pattern where you follow a specific approach.

I used to think that fasting all by itself would make me lose weight. But this isn’t true. The fact is, whatever fasting approach or meal frequency plan you follow. Know that calories in vs calories out are the most important factor in losing weight.

You don’t gain fat if you eat carbs after 8pm while following an intermittent fasting protocol or any other diet. You gain fat because despite your effort to follow an intemrittent fasting protocol. You’ve ate more calories than you’ve burned. So i’d advise you to find out your specific calories first. And then use fasting as a tool. Only If it helps you stick to your diet. Because for some people It doesn’t help them that much.

Myth 6 – Fasting Puts Your Body In Starvation Mode

Starvation mode is a myth. And the fact is that if you eat less than you burn consistently then you will lose weight. Think of it like this, say your body is a fire, to keep that fire going, you need to keep putting wood on it, otherwise, the fire loses fuel and goes out. Think of the human body in a similar sense. Food is the fuel that keeps you going, when you’re in a calorie deficit your body has to use your body fat stores and muscle as fuel/energy until you eventually have none left and die.

Take the Minnesota experiment, for instance, that was conducted to figure out how to help thousands of people starving in Europe and Asia after world war 2 to get back to a healthy body weight.

Over 6 months of severe calorie restriction, the volunteers basal metabolic rate dropped at the very most by 20%.

This proves that starvation mode isn’t a thing.

And if you practice some form of intermittent fasting, and engage in a resistance training program and eat a high protein diet. You’re almost 100% likely to maintain or increase your basal metabolic rate as you add muscle to your frame. This is because muscle is more metabolically active than fat. In simple terms, this means that the more muscle you have the more calories you need to eat to maintain that muscle.

This is why a moderate calorie deficit of 25%, a high protein diet and resistance training are your best bet for keeping your metabolic rate going strong. And if you miss breakfast while doing all of these things and fast. You will not go into starvation mode. Because starvation mode is a full-blown myth.

3 Main Benefits Of Intermittent Fasting – How Does Intermittent Fasting Work?

Although I’ve anecdotally experienced some of the many benefits of intermittent fasting. There are some objective benefits that are behind the reason intermittent fasting ( or also called I.F) works so well for many people.

I’m going to briefly discuss some of the benefits I’ve experienced while doing intermittent fasting, especially the lean gains approach popularized by Martin Berkhan that has you fast (not eat) for 16 hours and then gives you an eating window of 8 hours.

Benefit 1 – You Can Eat Bigger Meals While Simulatanously Losing Fat When Following An Intermittent Fasting Approach

Once your calories and macronutrients are set up for fat loss. And you try intermittent fasting (especially the lean gains approach) You will have 2-3 big meals, compared to 4-6 smaller meals.

If you’re like me and you don’t like to feel limited while dieting. Then once your body adapts to the new eating schedule. You can enjoy eating 2-3 larger meals.

But remember, you must be in a calorie deficit.

When doing this type of intermittent fasting I find that it doesn’t feel like I’m dieting.

Benefit 2 – No More Worrying About Meal Timing

If you’re used to eating 4-6 meals per day, meal prepping and the like. Then it can be quite enlightening to know that you don’t need to do that. You can actually go 16 or more hours without food and be fine. With no loss of muscle mass ( as long as you’re following a high protein diet and you’re resistance training).

I believe this realisation. Gives you freedom. And completely busts the smaller meals are better dogma.

Benefit 3 – Improved Mood, And Energy Levels Are Sustained More Easily

If You decide to take up intermittent fasting, you will be eating fewer meals, and with this comes the benefit of more sustained energy levels. Research shows interesting evidence that suggests glucose AUC levels are actually 30% higher when one group was eating 6 meals per day in contrast to a group eating only 3 meals per day. This points towards the conclusion that 3 meals per day are superior to ensure more steady blood sugar levels throughout the day.

The Most Effective Intermittent Fasting Protocols – How Does Intermittent Fasting Work?

There are many Fasting protocols out there. But from my personal experience. There are better and worse ways to fast. In order, I’m going to go in-depth on the fasting protocols that I believe to be most effective.

16:8 Intermittent Fasting Martin Berkhans Approach

This diet was the brainchild of fitness and nutrition expert Martin Berkhan, he also invented an extremely effective and fun way of training called reverse pyramid training (RPT). I highly recommend you visit his site. It’s full of some of the best fitness content on the web. Or read his book and support his work. The lean gains method linked below.

If you’d like to learn the specific lean gains approach I’d recommend you read his article on it. Because the way I do it, slightly differs to exactly how Martin does it. Martin advocates a protein target of 40-50% of your calories. I still aim for high protein but more to the 1-1.2 gram per pound of bodyweight range.

Think Of The 16:8 Method Of Dieting As Simply Skipping Breakfast

In a nutshell, you skip breakfast and push your feeding window to roughly 12-2 PM and then you have an eating window of 8 hours from 12- 2 PM to 8-10 PM depending on when you ended your fast (ate your first meal).

After you’ve finished eating for the day at 8-10 PM you then don’t eat anything through the night, you skip breakfast and resume your first meal at 12-2 PM.

And then during your 8-hour eating window you eat 2-3 meals. Although you can have however many you like ( as long as you don’t go over your calories). But the general recommendation is to eat 2-3 meals so that you can enjoy bigger meals.

This type of intermittent fasting is called the 16:8 diet because you fast (don’t eat) for 16 hours and then eat for 8 hours.

Martin also advocates that if you have 3 meals you should eat 40% of your calories after working out, and 30% for the last 2 meals respectively.

Or if you eat only 2 meals per day you could eat 50% of your calories for each of those meals.

Here is another way you can do it. Remember those percentages don’t have to be perfect and what matters most is that you hit your daily calories and macronutrients.

Simple example of Leangains intermittent fasting

A Day Using Intermittent Fasting – How Does Intermittent Fasting Work?

Simple example of Leangains intermittent fasting.

So as you can see this can work great for people who prefer bigger meals. And it actually isn’t that complicated.

There are a couple of other intermittent fasting protocols that can help you achieve your fitness goals. But I believe that most people will find that the lean gains way of intermittent fasting is the most sustainable in the long term.

Now I’ll quickly mention a couple other approaches worthy of attention.

Eat Stop Eat

Eat stop eat is a method of alternate-day fasting were you only fast once or twice per week. And each of those fasts will last for 24 hours.

I’ve already explained some of the benefits of fasting. But one other benefit is that it helps to induce autophagy It is believed that autophagy can be brought about by fasting. Autophagy can help cleanse waste from your body and can help provide you with energy and stave off chronic illnesses. Autophagy also has huge anti-ageing benefits.

That is to say, the eat stop eat diet is a diet that helps you experience the benefits of fasting, without committing to long daily fasts.

Its also very straight forward.

Let’s say that you wanted to try the eat stop eat approach and fast for 2 days per week with each fast lasting for 24 hours on non-consecutive days.

Here is what a week might look like.

Monday – Eat Normally.

Tuesday – Eat your last meal slightly before 9AM.

Wednesday – Fast (Don’t eat) for 24 hours and resume eating just after 9AM.

Thursday – Eat normally.

Friday – Eat normally.

Saturday – Eat your last meal before 9AM.

Sunday – Fast (don’t eat) for 24 hours and resume eating just after 9AM.

So as you can see it’s very straightforward.

And remember if your goal is fat loss energy balance (calories in vs calories out) is still the most important factor in you losing weight. And you need to aim to be in a weekly calorie deficit of 3500 calories ( because one pound of fat consists of roughly 3500 calories).

Eat Stop Eat For Fat Loss – How Does Intermittent Fasting Work?

Say for example you wanted to lose fat and your maintenance calories were 2000 per day (you need to eat 2000 calories per day to maintain your weight). Here’s what a week of eating might look like.

Monday – 2000 calories.

Tuesday – Eat an apple and consume a protein shake (total of 200 calories) before your fast at 9 AM.

Wednesday – Fast for 24 hours don’t eat anything until after 9 AM and then eat 2000 calories through the day.

Thursday – Eat 2000 calories.

Friday – Eat 2000 calories .

Saturday – Eat an apple and consume a protein shake (total of 200 calories) before your fast at 9 AM.

Sunday – Fast for 24 hours don’t eat anything until after 9 AM and then eat 2000 calories through the day.

So as you can see, because of the 24-hour fasts twice per week you can split your calories over 5 days.

Allowing you to eat at your maintenance calories 5 days per week while being in a weekly calorie deficit.

This approach isn’t for everyone. And many people may not enjoy fasting for that long. But it’s just another tool in the toolbox.

For the book on this method in detail, read Brad Pilon’s book below. Eat stop eat.

The Warrior Diet – How Does Intermittent Fasting Work?

This is a diet created by Ori Hofmelker, in 2001 who is a former Israeli special forces member.

The warrior diet is very similar to the lean gains 16:8 way of fasting but you have a bit more freedom while fasting and you have a shorter eating window of only 4 hours.

On this diet, you essentially fast for 20 hours and eat for 4 hours. In my opinion, it should be called the 20:4 diet to minimise confusion. But it does deviate in a couple of ways from the lean gains approach.

During your fasting period, you can eat small portions of eggs, dairy, alongside raw fruits and vegetables. Ori also emphasises the importance of drinking plenty of non-calorie fluids.

And during the 4-hour eating window, you are encouraged to eat as much food as you need. This is the only downside with the diet (in my opinion) because if you eat intuitively without any former experience tracking your calories, you could easily eat too much and reverse your progress.

How Does Intermittent Fasting Work? A Day In The Life Of The Warrior Diet

06:00 – Get up (after fasting all night and continue the fast)

07:00 – Fast

08:00 – Fast

09:00 – Fast

10:00 – Fast

11:00 – 1 egg

12:00 – Fast

13:00 – Fast

14:00 – Apple

15:00 – Fast

16:00 – Fast

17:00 Fast

18:00 – 22:00 Eat one big meal prioritising protein in this 4 hour window.

22:00 – 18:00 fast again.

Because the warrior diet allows you to have a small feeding of fruits, vegetables and protein during the fast it’s not really a proper fast. This is because a proper fast means that you consume no calories at all. In the Leangains approach and eat stop eat you can only consume 0 calorie beverages and not eat any calories. Although the only exception for lean gains is that you can have either 15 grams of BCAA’S or a scoop of whey protein before working out.

Personally, if I do the lean gain approach I’ll drink a whey protein shake (1 scoop) with water before working out. And then try to postpone my eating window for as long as I can. But I normally eat around 2 pm when doing lean gains. And break my fast with a high protein meal. Such as fat-free cottage cheese with a scoop of protein and a piece of fruit. Or some meat, veggies and a starchy carb.

If you’ve never tried fasting before I’d highly recommend trying the lean gains approach. Because it’s very liberating to experience that you don’t actually need to eat every few hours. And that in actual fact you can do fine not eating for 16 hours or more.

How Does Intermittent Fasting Work? You Must Stay Hydrated

Whether fasting or not. Its extremely important to stay hydrated. Drink at least 1 litre of water for every thousand calories you expend.

Will Fasting Make You Hungry?

In the beginning, it will. Because if you’re used to eating breakfast. Your bodies hunger hormone ghrelin will be too. But after a couple of weeks of fasting, your ghrelin will adapt to the new pattern of eating and you won’t get hungry.

The Bottom Line On How Does Intermittent Fasting Work?

  1. Intermittent fasting does provide some clear cut benefits such as your energy levels will be more stable (this will improve your mood because your blood glucose levels will be more steady), you can eat bigger meals while losing fat, no more worrying about meal timing and getting your 5-6 meals in, and helps to induce autophagy.
  2. On the other hand, doing intermittent fasting without knowledge of the fundamentals, things like energy balance and understanding macronutrients and tracking your calories appropriately is putting the cart before the horse. I actually made this mistake when I tried this approach years ago. And made zero progress. But now that I have a good understanding of the fundamentals and how to use them I really like intermittent fasting. Especially the lean gains approach.
  3. Intermittent fasting is a great tool when used properly. But remember regardless of your meal frequency. Calories are king and protein is queen.

Thanks for reading and I hope that I’ve addressed the question how does intermittent fasting work? in this article.

If you need any additional help with your fitness goals or just want to ask a question. Send me an email at

If you want a free ebook that will show you definitively how to lose fat. Click the link below.

Published by henrypaget

Hi, I'm Henry and it's my mission to help you succeed with your fitness & health.

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