20:4 OMAD Intermittent Fasting | Protocol Guide For Weight Loss


The One Meal A Day, also known as OMAD, is a sure strategy to lose weight healthily and efficiently.

I suppose you have learned about or even tried intermittent fasting before, and now you are wondering about the 20:4 protocol. You heard stories about people living this One Meal A Day lifestyle, and you can’t imagine how they manage and if it is a healthy and sustainable approach for fasting or even fitting for your weight loss goals?

Well, you came to the right spot, my friend.

Like you, I was dazzled with many questions about what to drink during fasting and how to pass 20 hours with zero calories. There was no better way to know it all than trying it myself.

So I did–for 2 years.

This is not just another cookie cutter article about intermittent fasting–this is an in-depth review of everything you could possibly want to know (or not want to know) about the 20:4 OMAD intermittent fasting protocol.

Among the various intermittent fasting protocols, in my opinion, the 20:4 and OMAD are the most thrilling methods. They require special self-discipline and a warrior’s attitude, but they promise gratifying results.

In this article, I share my testimony and the lessons learned from my two years of OMAD fasting. 

If you read my story to the end, you will learn:

  • Is OMAD the right protocol for you?
  • Learning to control your hunger.
  • Beginners’ mistakes to avoid. 
  • Eating & drinking options.
  • Exercising benefits during fasting.

Why I Prefer The OMAD Protocol? (Versus 20:4 & Warrior Protocols)

benefits of fasting
Source: @healthcoachkait

20:4 fasting is done in a straightforward 20 hours of fasting followed by 4 hours of eating. 

Assuming it is the same as One Meal A Day is not wrong, given that your one meal is within that four-hour window. Some would regard OMAD as a type of 23:1 fasting, but the difference is trivial. 

Some would recommend having the eating hours during the day. But, I do it the Megan Fox way and eat my only meal in the evening. It is up to you. 

Another common variant of 20:4 is the Warrior Diet, introduced by Ori Hofmekler. In that model, even during the 20 hours window, you can eat a low-calorie diet. But that is a different story than ours today.

Before I actively started intermittent fasting, I used to skip breakfast. Lunch was more a chance for socializing with coworkers. When I shifted to working from home mode, It was easy to skip breakfast and lunch entirely and adopt a One Meal A Day. 

For these reasons I adopted a 20:4 protocol, it will also be good for you if: 

  • You can easily skip one or two meals already. 
  • You are looking for a lifestyle change more than a diet. 
  • You want to feast, not to count calories. 
  • You want to save time and money consumed in multiple meals. 

If yes, let’s get you started!

Winning The Hunger Games

I am a big believer that intermittent fasting mastery relies primarily on knowing how to put your hunger under control. 

Hunger is the monster that stops 90% of people I know from starting with OMAD or extended fasting protocols. 

And like other monsters, hunger is intimidating, over-feared, and fictional! 

It is absurd to say that hunger is simply not real, but, in my opinion, it is usually self-made–or at the very least, a mental state, that you get programmed to over the years–but it is not true most of the time. 

Real hunger equals starvation. And I am pretty sure that the hunger you fear is not starvation. You do not fear to starve; you just experience false self-defense against starvation.

Why do we feel hungry when we should not? 

Look at yourself in the mirror. Do you really think your body lacks energy sources, and it will break down if you skipped your lunch today? 

Imagine you are raising a kid. You feed him something every mealtime, and when you are a bit late on a meal, he cries, so you get up and cook him something. That kid is your body, and his cries are your hunger. 

One time, it is time for breakfast, and you are late to feed him. He starts crying for food, but you ignore him. He keeps crying. Then you tell him to open the fridge and eat something;he doesn’t follow and shouts even louder, but you keep ignoring him.

At one point, he will find crying pointless and start eating from the fridge. That fridge is your fat store. 

The day passed, and you skipped cooking breakfast and lunch. The kid might repeat the scenario the next day, but it won’t take more than a couple of days until he gets used to it. Later whenever he needs food, and it is not dinner time, he will open the fridge–no crying, no hunger. 

Simply said, hunger is your body’s alarm that you need food.  And yes, it is what you programmed it to be, based on your lifestyle. 

The very original use of hunger was to signal malnutrition, so your body wouldn’t suddenly break down. 

Over the modern ages, we messed up that alarm system. As we get used to 3 meals a day, our bodies forget about fat stores; they now rely nearly 100% on external food intake. 

Your kid is what you raise it to be. You feed your body breakfast every day; it will demand food in the morning and signal “false” starvation if you miss it one day. 

To win the hunger games and achieve weight loss results, you need to bring your body back to its original state; to teach it a new schedule of eating and to let it slowly remember where the fat stores are and how to utilize them.

OMAD Fasting Beginners Mistakes 

OMAD fasting mistakes for beginners
Source: @martinfeasts

I failed so many times in the beginning. One good thing about failing so often, that you learn how to start right. So here are the most common mistakes. By overcoming them, you can get over the typical hardship of the beginning. 

1) Starting Big. Don’t jump into OMAD or longer fasting protocols if you have not done any intermittent fasting before. Follow a 16:8 protocol for a couple of weeks before you get into 20:4. Shocking your eating routine doesn’t lead to a sustainable change. 

2) Missing A Vision. You may manage to survive a single-meal day easily, but that is different from adopting a One Meal A Day routine. You need a vision, and this is not business consultancy crap. It is essential to know, practice, and announce what you intend to do. You need to learn a lot about the 20:4 protocol, believe in your health goals, and let your friends and life partners know about it.  

3) Dehydration. Lacking water or dry fasting may sabotage your 20:4 diet. Randomized controlled trials show that drinking water can increase energy expenditure and fat oxidation when insulin concentrations are not elevated [1]. Meanwhile, dehydration increases irritability and incidences of headaches and sleep deprivation [2]. 
4) Dirty Fasting & Overeating. While I might advise trying dirty fasting on your very first long fasting (+20 hrs) days, it is a common beginner mistake to eat and drink things that break the fast and then get frustrated from unsatisfying results.

Dirty fasting is consuming few calories during your fasting window. It happens when you use cream drops on your coffee, add lemon juice to your water, or drink a cup of bone broth during fasting. It would be good to ease up your first days of fasting with one or two cups of creamed coffee, but you should not get angry at your scale if you have not lost weight after three days of fasting if you are drinking a glass of milk during fasting. The same problem happens if you start overeating on your eating windows—more on that in the upcoming section.

Drinking & Eating For 20:4 Diet  

what to eat on OMAD
“movienight ???? at least low calorie drink you have to set priorities” Source: @puppiknolli

The most common questions I have seen on most intermittent fasting groups were about what is allowed and prohibited during fasting. 

It seems like a resistance to the concept of zero calories—a quest for exemptions. 

Let’s get this first clear. There is nothing with absolute zero calories except plain water. 

So even a herbal teacup has about 1 calorie, black coffee has 2 calories per cup. What about Cola-Zero? Same. 

The FDA allows producers to claim “calorie-free,” “free of calories,” “no calories,” or “zero calories” labels on products that contain less than five calories per reference amount customarily consumed and per labeled serving [3].

But hey! Why should one be seeking 0-calories anyway?

Everyone wants to induce autophagy—this housekeeping process is linked to cleansing and anti-aging effects in humans. Research shows that calorie restrictions can cause a strong autophagy response in the body [4]. 

That is what everyone is after; restrict your calories to reach autophagy. And to maximize the effect, you maximize the restriction, hence Zero-Calories. 

While there are many scientific debates about it, many still argue that ultra-low calories would not kick you out of fasting. 

That is where the term “Almost Zero Calories.” came into the fasting game. 

That is where you should start. Do not seek zero calories! In my strategy, I prefer to seek zero food and control my drinks calories. 

To conclude then:

Rule #1: What to EAT during the fasting window? 


No physical food. 

It doesn’t matter if you are an absolute beginner or which goal you seek. You can follow a 16:8 for shorter fasting or a 5:2 intermittent fasting protocol with 500 calories during the fasting window. But if you want to do OMAD, then no meals and no snacks during fasting. It is not about calories; it is about losing these harmful modern habits.

Rule #2: What to DRINK during the fasting window? 

For Beginners: Water, Tea, Black coffee. No sugar. Mix the drinks as you please. Allow yourself the freedom of having some lemon taste on your water or a flavored tea, use cream to whiten your coffee, or add a zero-calorie sweetener. But know that this is a temporary exemption, just to get you ready for the next stage.

For Advanced (Tried OMAD over a couple of weeks): It is time to go into the ultra-low-calorie mood. Maybe a slice of lemon, but not squeezed, could be added to water; 2 cups of coffee maximum, and no creamer or sweeteners whatsoever. Also, limit the number of teacups and avoid the flavored and sweetened types.

Suppose you seek maximum effect on an experimental level. In that case, you may try only plain water fasting and track the difference, especially if you are following intermittent fasting for some therapeutic purposes.

Rule #3: What to EAT & DRINK during the feasting window? 

I like to call it the feasting period for that purpose. You should feast. Feel the freedom that this lifestyle offers you. Celebrate your eating window with all what you wish: no calorie counting, no restrictions. Yet, there is a “but”. 

You will be surprised after you successfully finish fasting that you are (unconsciously) asking yourself, “Do I really want to break my fast on that Big Mac Combo?” 

Managing 20 hours of fasting generates an incredible (feeling-good about yourself) state. And yes, you better use it in your favor. This can be done by following–as much as you can–these guidelines for food selection during the feasting window. 

  • Eat something you cook. Avoid fast food deliveries. 
  • Mix intermittent fasting with keto to maximize autophagy and weight-loss effects: High fat & low-carb at feasting. 
  • Diversify your single meal. Remember it is the only meal today; you need minerals and vitamins from vegetables and fruits, you need some protein sources and fats. 
  • Avoid sugary and high-carb food. These will do you two harms: they raise your calorie intake, which can reverse your gains during fasting, and they will elevate your insulin levels and promote hunger later during the fasting window. 

Exercising During Long Intermittent Fasting

That is the last and most exciting lesson learned. 

I won’t say you can exercise during fasting. 

I say you should exercise during fasting. 

In contrast to the common misconception, I did have more energy during my fasting window than usual. 

On top of that, you get much more motivated to exercise during fasting days. 

It is all in your mind. Starting your day deciding to take control of yourself and fast, you have just set the commitment bar so high. 

Psychologically, it becomes much easier to take a walk to the gym or step on your training mat. 

I typically do a 20 minutes HIT (High-Intensity Training) in the morning of my fasting day. Occasionally, before my dinner (only) meal of that day, I will have another 1-hour training session.

Exercising during fasting will boost your fat-burning rates and simultaneously stimulate the growth hormone to prevent any mass loss in your muscles. 

Yet, it is essential to mention that if you suffer special medical conditions or undergo prolonged physical training, you first need to consult your doctors and fitness managers.

Put It into Practice: 3 Impactful Takeaways to Implement

  • Try OMAD: Consider trying the One Meal A Day approach, which involves fasting for 23 hours and consuming one large meal in a 60-minute window.
  • Practice self-discipline: The 20:4 OMAD intermittent fasting protocol requires self-discipline and promises gratifying results. Practice self-discipline to achieve your goals.
  • Control hunger: Intermittent fasting mastery relies on knowing how to control hunger. Learn techniques to control hunger during fasting periods.

The Bottom Line

I believe that a 20:4 diet is a return to nature. 

It should be the goal of intermittent fasting followers.  

In addition to its proven benefits for weight loss and general health, a One Meal A Day protocol is a significant improvement to your lifestyle and your ability to get in control of your hunger. 

During your 20 hours of fasting, you can (and should) exercise while keeping water always close and avoiding sugary beverages. 

After your long fast, eating becomes feasting–more pleasurable with motivation to keep it healthy and free of junk food.

With the right combination of fasting, hydration, exercises, and healthy feasting, 20:4 fasting will be a celebrated part of your life. It will not only enable you to lose weight, but it promises a sustainable solution for high energy, better mood, and anti-aging benefits.

Daniel Maman

Daniel is a certified personal trainer (ACE), has a Bachelors of Science degree in Sports, Exercise, and Wellness, and spends his free time keeping up to date with the latest research in health and fitness. In his free time, you can find him playing basketball, doing muay thai, camping, traveling, reading, and eating tomatoes like they're apples.

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  • Written by: Daniel Maman
  • ACE Personal Trainer
    BSc Sports, Exercise, & Wellness
  • Last Updated on August 3, 2023

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