One Meal a Day Fasting: Should You Try It?

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One meal a day eating is on the rise – we’ll explain everything you need to know about this practice of fasting and will help you determine if it’s a good fit for your eating goals!

One Meal a Day (aka OMAD) Intermittent Fasting: Should You Try It?

Have you heard the buzz about the intermittent fasting approach known as OMAD (One Meal a Day)? 

Perhaps you’ve started some form of intermittent fasting, have just conquered 14, 16, or even 18 hours of fasting, and are enjoying breaking your fast each day with a late lunch, a snack, and then a full dinner. But now you hear many IF-ers are leaning toward an OMAD approach. Wait..what?

Now you have to hold off even longer and can only eat one meal each day if you want to be healthy and lose weight? Before you jump off the OMAD train, let’s take a look at what OMAD really means. Where did this trend get its roots? Is eating one meal a day bad for you? Are there benefits to this approach?  Should you become an OMAD-er? We’ll explain it all!

Where Did OMAD (One Meal a Day) Come From?

A Preface About Diets vs Lifestyle Eating: At Life Health HQ, we don’t consider any form of intermittent fasting a “diet” for quick weight loss.  Intermittent fasting (IF) is an eating lifestyle that requires long-term, significant commitment for success. In this article, we’ll discuss how OMAD’s origins come from famous diets. While we’ll include the full context of the initial beginning’s of OMAD in this article, it’s important to understand that OMAD isn’t a quick fix diet.

The idea of eating just one meal a day can be traced all the way back to Roman times, according to food historian Caroline Yeldham when eating more than the traditional noon meal was considered glutinous.

roman times

Over time, breakfast was added as a social way to start the day and eventually as a perceived way to gain energy to fuel the day. Clever marketers led us to believe breakfast was the most important meal of the day and that frequent eating would keep our metabolism revved up! Slowly, as food became more convenient to process and package, and fast-food was available on every corner, three meals a day plus snacking became standard.  

But in 2011, the one meal a day practice came back on the scene, this time as a newer diet technique.

Ori Hofmekler reintroduced this form of eating with his Warrior Diet. Based on the idea of eating like ancient warriors did, where they fasted throughout the day and then feasted in the evenings, this was a new approach to fasting that gained some mild popularity in the early 2000s.

warrior diet fasting

Followers of this plan choose a set 4 hour period of time each day when they can potentially eat, but within that window, they may pick just one hour when they can feast.

That single hour can change each day within the 4 hour period, allowing for some flexibility to accommodate schedule issues and vary fasting lengths. The plan promised the benefits of intermittent fasting like lower insulin levels, increased human growth hormone, weight loss, cellular repair, and more.

Other versions of OMAD have since emerged throughout the last decade, limiting the types of food you can eat for your one meal a day, the length of time you have to consume your one meal a day, and the quantity of food you can consume.

Some OMAD plans even provide guidelines for the size of the plate and the height your food can be piled on that plate (no more than 3 inches). But generally, there are three basic styles of OMAD eating:

OMAD OPTION 1: 1 HOUR EATING WINDOW

Eat within the same single hour each day, allowing for a true 23 hour fast (consuming only water, plain sparkling water, black coffee or tea during the fasting hours) and eating a healthy balanced large meal during your eating window.

OMAD OPTION 2: 4 HOUR EATING WINDOW

Set a 4 hour window of time each day. Within that window, pick one hour for your meal. This gives flexibility for a 20-26 hour fast each day (see Warrior Diet).  

Here’s an example of what the 4 hour OMAD diet looks like with a time window between 5-9 PM:

  • Day 1: Eat your meal between 8-9 pm and then begin fasting.
  • Day 2: Eat your meal between 5-6 pm (you’ve ended your fast at 5pm for a 20 hour fast, and start new fasting period at 6pm that evening). 
  • Day 3: Eat your meal between 7-8 pm (you’ve ended your fast at 7pm for a 25 hour fast, starting a new fast at 8pm, and so on.

OMAD OPTION 3: 4-5 HOUR EATING WINDOW

Eat a small snack, a regular meal, and even a dessert or another closing snack within a set 4-5 hour timeframe each day.

This more extended “single meal” is more commonly thought of as regular intermittent fasting, but is supported as a version of OMAD by Dr. Bert Herring and supported by Gin Stephens in her One Meal a Day IF Lifestyle Facebook Group

What Is The Logic Behind OMAD Eating?

Though there are many different variations of one meal a day eating diets and plans, there are pretty much two schools of thought behind the logic of OMAD eating:

  • THEORY 1: OMAD works because it is a calorie restriction diet plan 
  • THEORY 2: OMAD works because it is a time-restriction eating plan

Theory 1: OMAD Works as a Calorie Restriction Diet Plan

Theory one centers on the calories in/calories out model. Anyone who switches from eating three meals a day plus snacks to one meal a day is naturally going to reduce calorie intake and lose weight.  

As the chart shows below, if your three meals and two snacks per day typically reach a total of 2000 calories, by switching to just one meal a day, even if you increase your food significantly for that one meal, you will end up with a calorie deficit.

If we look at the numbers on a weekly basis, eventually that calorie deficit will be reflected on the scales and in your weight. 

Regular Daily Calorie Intake OMAD Calorie Intake
Number of MealsBreakfast, Lunch, Dinner, and Two SnacksSingle Meal
Calories Per Day2,000 Calories1,200 Calories
Calories Per Week14,000 Calories8,400 Calories

Using the table above, we can see that transitioning from an average calorie intake to OMAD would generally results in a reduction of 800 calories per day, or 5,600 calories per week!

Assuming normal resting metabolic rate and average calorie burning:

  • If 3,500 calories  = 1 lb, a 5,600 calorie reduction would yield a 1.6 lb loss per week.

OMAD should work well based on a calories in / calories out model! Sounds reasonable, right? But looking at OMAD with this mindset may not be the best approach and Dr. Jason Fung, the guru of all things fasting, explains why

All calories are not created equal, and simple calorie reduction does not work for the long term. One common overlooked variable in the calories in / calories out model is that our bodies adjust to our calorie intake and expenditure fairly quickly, and so our calories out eventually change and we can’t rely on that set amount of weight loss based on a simple calorie deficit alone.  

If we could, we would just keep losing 1.6 pounds every week we practiced OMAD!

To further illustrate, let’s go back to our OMAD example.  So we have a 175 lb person, eating 5,600 calories less per week. Which results in a loss of 1.6 lb per week.

  • Let’s say you have an individual starting at 170 lbs.
  • After 1 year of losing 1.6 lbs per week, they would be at 86.8 lbs (unhealthy and way underweight)
  • After 2 years of losing 1.6 lbs per week, her weight would be 3.6 lbs… aka dead!

Obviously this is not a logical or realistic theory for how or why OMAD works! And it further illustrates how absurd it is to think any calorie restriction diet plan will consistently work this way for you long term.

Dr. Fung does a great job of explaining this flawed idea with his refrigerator/freezer analogy (be sure to watch all the way to the end)! 

Theory 2: OMAD Works as a Time Restriction Eating Plan

A more logical way to view one meal a day eating is to consider it a time-restriction eating plan which ensures a lengthy period of fasting. As an effective form of intermittent fasting, it offers a host of benefits we’ll get to a little later.

OMAD works because you are allowing your body enough time (up to 23 hours of each day) to deplete its glycogen stores and train itself to use its own body fat rather than insulin, for fuel. This process is known as fat adaption and though it can be achieved a number of ways, the OMAD form of intermittent fasting is one of the most sure-fire methods to get the job done.

Theory 2 relies on time-restricted eating rather than calorie restriction. It is fairly easy to measure how many hours each day you put food in your body, and thus just as easy to keep track of the number of hours you fast from all food sources. OMAD-ers understand that the magic lies more in the fasting hours than in the feasting hours.

omad fasting hours

It is during the fast that insulin is kept from spiking by not consuming anything except plain water, black coffee, or plain tea. By removing insulin from the equation, our bodies must search for another energy source and tap into our own fat storage! Voila! Weight-loss plus a host of other benefits!

Is Eating One Meal a Day Bad for You?

But isn’t eating only one meal a day bad for me? Won’t it slow down my metabolism and send me into starvation mode? What will happen if I have two or three meals some of the time? Won’t I want to binge eat during that one meal?

We need to look at the possible negative effects of OMAD.

1. OMAD may not be a one-size-fits-all plan.

Those with less weight to lose or people with already speedy metabolism may have a very hard time fasting for more than 20 hours, which is required for this form of fasting.

If your body becomes stressed from fasting, you may start to feel consistently sluggish and weak. Some stressed bodies give off cortisol causing interrupted sleep. These are signs that you may need a slightly shorter fasting window or several meals each day rather than one.

omad sleep problems

2. OMAD can lead to making bad food choices.

If you aren’t careful to do some meal planning, you may find yourself digging in to whatever is available once your eating time arrives. Taking the time to prepare a healthy balanced meal may require more self control than you have after 23 hours of fasting, so be sure to plan ahead.

That’s not to say that with OMAD, you can’t enjoy foods you love and even indulge in treats that were often off-limits with old diet plans. But especially with OMAD, it is important to be sure you are getting proper nutrition when only eating once each day.

3. Your body can adjust to OMAD, just like any other food plan.

This is not so much bad for you, as it is something you must be aware of. IF expert Gin Stephens, suggests changing the quantity and types of foods you eat each day, within your OMAD eating window, so that your body does not become used to one set pattern of eating. Mix it up! 

4. OMAD can be misunderstood or executed incorrectly.

One of the biggest mistakes followers can make with this plan is in thinking they will lose weight even faster if they also restrict their calories for their one meal a day.  Not eating enough food and not making sure the foods you eat are rich in healthy fats and nutrients could cause problems.

Less (during your eating window) is not more when it comes to OMAD.  

When done correctly, OMAD will not slow metabolism or cause your body to think it is in starvation mode. Your body will simply turn into a fat burner and operate more efficiently.

Eating One Meal a Day Benefits

Now that we’ve covered potential drawbacks of OMAD, let’s discuss the benefits of eating one meal a day!

1. It’s a simple concept.

No calories to count, no expensive special foods to buy, and only one meal to prepare each day. Once you conquer the art of fasting, most people who practice OMAD say it is the easiest and most freeing lifestyle they’ve tried. For a gentle approach, start fasting gradually and perhaps work up to OMAD.

2. It minimizes hunger and cravings.

Although the first few days can be a struggle while adjusting from operating as a sugar (insulin) burner to a fat burner, once the transition is made, most OMADers report their hunger and cravings are gone because their insulin is not continually being “spiked” by frequent meals and snacks being introduced into their systems. This makes the one-meal-a-day eating practice much easier to follow as a long-term lifestyle.

3. It’s reported to provide greater mental clarity.

Dr. Berg, a chiropractor who specializes in healthy weight loss methods, explains that because fat is a more efficient fuel on which to operate, when we’re OMAD-ing and avoiding insulin spikes, our pathways aren’t stressed and brain fog is removed. Many people report an almost euphoric or at least energized state.

omad mental clarity

4. It increases autophagy.

Autophagy is the awesome process of our body’s ability to self-eat our bad and damaged cells. This process is increased while we are in the fasted state, making it possible to reduce cancer cells, improve skin condition, and renew aging cells. Pretty awesome!

5. It helps break through plateaus.

If you’ve been struggling with losing weight or at a standstill with other health issues, the OMAD form of fasting may be just the healing tool you need to change the status quo and stimulate a sluggish metabolism.  

Should you become an OMAD-er?  You can be your own study of one! Start slowly. Extend your fasts gradually and trust the process. This is not a quick fix and you may need to give it a good 30 days before you are comfortable with this method. 

Are you a one-meal-a-day eater? Let us know how you do and if OMAD works for you!

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