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Home arrow Nutrition arrow Intermittent Fasting arrow OMAD Diet – What It Does to Your Body

OMAD Diet – What It Does to Your Body

Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 17, 2023
8 min read 1679 Views 0 Comments
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Looking for a diet that will really test your willpower? OMAD might just be the thing for you.


The OMAD diet is pretty self-explanatory. It stands for “One Meal a Day” and involves exactly what you think it does.

When you follow this diet, you’ll be restricting yourself to one meal a day in an attempt to achieve weight loss, similar to the intermittent fasting diet, just with fewer meals.

While there are plenty of sources online that sing the praises of the OMAD diet, we will take an in-depth look at it to determine whether it’s worth your time. Restricted eating is a tricky thing, after all.

Read on for more.

OMAD Diet – Is It Worth Trying?

The One Meal a Day diet, or OMAD diet, claims to help you lose weight by forcing your body to burn fat. It is a type of intermittent fasting, where you alternate between a period during which you can eat anything you want and a period where you are fasting or eating nothing at all.

OMAD is a stringent diet since you have to avoid eating for 23 hours a day, then get all of your calories in just one meal a day during a 1-hour eating window. Eating only one meal like this is supposed to make sure your body continually burns fat throughout the day, which helps with losing weight.

Like other intermittent fasting methods, eating just one meal a day is a way of altering how your body finds and uses fuel. When you eat in a more traditional pattern, your body draws energy from your food, but when you consume carbs, your body breaks them down into sugars.

When you have more sugar in your blood than what your body needs, insulin will carry this blood sugar to your fat cells, but if you do not eat for extended periods, your body will produce less insulin.

Your cells will still need energy for furling, so your fat cells will begin to release energy to make up for this deficit, though you have to avoid eating for long enough for this to happen.

Is Eating One Meal a Day Bad?

For most people, eating one meal a day (OMAD) to lose weight will not yield any dangers other than the pesky discomfort of feeling hungry for most of the day. However, it would be best to be wary of a few risks of cardiovascular disease associated with OMAD and intermittent fasting in general.

Intermittent fasting diets like the OMAD diet can increase your blood pressure and cholesterol, so if you already have concerns in either of these areas, then it might not be safe for you to eat just once a day. The OMAD diet can also cause your blood sugar to increase.

OMAD researchers have asked people to eat their single meal between 4 PM and 8 PM. These participants were healthy adults, and during this study, they were found to have higher blood sugar levels in the morning than usual, with their bodies being less capable of compensating for this increase.

Can You Lose Weight by Eating Once a Day?

While you’ll find plenty of people ranting and raving about the effectiveness of the OMAD diet for weight loss, there is little research and evidence to support these claims.

Studies have shown that intermittent fasting might help people lose weight, though several risks are mentioned with this eating pattern, such as rebound body fat increases. 

Furthermore, a study focused on the OMAD diet had participants eating their daily calories during a 4-hour eating window in the evening. Many saw improved weight loss and fat burning, while others experienced higher blood pressure and cholesterol.

What Happens if You Eat One Meal a Day?

There are a number of things that happen to your body when you’re only eating one meal every day. For example, you might feel hungry, and this feeling can lead to overeating later.

Dietitians worldwide agree that if you are only eating one meal a day, you will probably overeat during that meal since your body will be ravenous and need quick energy.

This one-meal intermittent fasting method can also slow down your metabolism as your body tries to hold on to as much of that energy it already has as possible. 

This can defeat your efforts at weight loss and caloric restriction and any other health benefits you were hoping to experience. Without a high-functioning metabolism, losing weight becomes quite tricky.

You likely won’t be getting enough nutrients either. 

When eating a single meal a day for weight loss, we are more likely to turn to high-calorie, low-nutrient foods like pasta and proteins because of the dip in glucose we experience during this caloric restriction. 

If your goal is weight loss, but you’re gorging yourself on carb-rich, processed foods during your eating window, perhaps you should consider a different weight-loss method.

Benefits of Eating One Meal a Day

There are, of course, a couple of health benefits to the OMAD intermittent fasting method that we can’t go without discussing. Here are some of the most prominent ones:

#1 Mental clarity

Constantly having to get up from your desk to get yourself something to eat can negatively impact your mental clarity and focus. But when you’re on the OMAD diet, rather than necessitating frequent meal breaks, you’ll be going through long, unbroken periods where you can focus on creative pursuits, your loved ones, and your business ideas.

You’re essentially helping yourself stay in the flow for longer. And, with fewer distractions (i.e., getting up to make food), you’ll experience better focus, which leads to improved overall mental clarity.

#2 More energy

Research has also shown that OMAD can elicit specific hormonal changes in the body that cannot help you focus for longer but actually provide you with more energy throughout the day. 

During your fasting period, your body will produce greater levels of energizing hormones such as norepinephrine and adrenaline.

Not only do these hormones boost your focus, but they also have the ability to improve your metabolic function. This becomes important in the next point.

#3 Weight loss

Studies have found that eating within a daily 4-hour window can lead to much more effective weight loss than eating fewer calories in a day while consuming three meals a day. They have also shown that intermittent fasting can burn through visceral fat quicker than a low-carb diet.

OMAD activates a metabolic state known as ketosis, during which the body metabolizes your fat into energy molecules known as ketones. This essentially means that your body begins to break down fat and use it as energy.

Norepinephrine, the hormone we mentioned earlier, not only improves mental clarity but can prevent your metabolic rate from dipping during your daily OMAD fasts.

#4 Improved discipline

This is one of the most significant and underappreciated benefits of the OMAD diet. 

When you learn to restrict your eating to just one period during the day, you are practicing an incredibly challenging form of discipline not many people would be able to tolerate. As such, you are becoming more disciplined as a person, and this skill will translate into other areas of your life.

You’ll learn to be more patient and appreciate what you have more. OMAD is not all about becoming slimmer, after all.

#5 Reduced inflammation

Fasting methods like OMAD have been used to reduce pain and inflammation for millennia.

However, more recent studies have found a number of anti-inflammatory benefits to fasting – OMAD can reduce inflammatory markers such as C-reactive protein.

Lower inflammation levels are also associated with other benefits like improved overall health, reduced neurodegeneration, and a longer lifespan. 

These benefits are associated with fasting techniques outside of just OMAD as well, so you can experience them from most forms of intermittent fasting.

Risks of OMAD

Unfortunately, there are a number of risks associated with OMAD that we can’t do without mentioning.

#1 Fatigue

As we mentioned earlier, if you are not getting sufficient nutrients during your OMAD eating window, your blood sugar will begin to dip, which causes a whole host of other adverse side effects. 

For instance, you will begin to feel weak, shaky, and exhausted all the time. Your body needs fuel to survive, and it can only take you so far when it starts burning fat for fuel.

If you find that you are always tired and exhausted while following the OMAD diet, you should probably consider another less restrictive diet.

#2 Extreme hunger

Naturally, when you are fasting for most of the day, you will feel extremely hungry. Even if you spend a good portion of your fasting period sleeping, this is true.

While being hungry might not sound like the most significant thing in the world, when you’re constantly starving all day, every day, you’re going to become irritable and be more prone to giving in to your cravings.

#3 Binge eating

You are far more likely to binge eat when you are following OMAD.

When your eating period finally rolls around, you are far more likely to fill up on foods that aren’t particularly healthy, like fast food, lots of carbs, and sugary drinks. This can seriously halt your progress and negate any health benefits you’d hoped to see from the diet.

#4 Possible harm to your mental health

Your mental health can also take a toll when you’re restricting your eating as severely as you do on OMAD. We are constantly exposed to food imagery every day, and when you have to avoid eating for most of the day, this imagery quickly becomes torturous.

The weight loss effect of OMAD also comes as slow progress, and being hungry all day for a month, only to notice a difference of 1–2 pounds in your weight, can be highly demoralizing.

Finally, there’s a delicate balance that you have to strike with this diet – you have to make sure you’re eating all the right foods, getting a proper caloric intake, and eating the right nutrients. Otherwise, you won’t see any progress.

Who Shouldn’t Practice OMAD?

This diet can be dangerous to children, the elderly, and those who are struggling with health conditions like diabetes or cardiovascular disease. Pregnant women also should not practice OMAD. These groups need a steady caloric intake to maintain proper health.

What’s more, people who take prescription medication regularly should not follow OMAD since many medications must be taken with food several times a day.

What Should I Eat and Avoid at My Eating Window?

There are no food or calorie restrictions on this diet unless you decide to do keto OMAD. In general, it’s best to eat nutritious foods, such as fruits, vegetables, nuts, eggs, fatty fish, and poultry. Avoid junk food, alcohol, and sugary drinks in your eating window as they can halt your progress. 

You should be aiming to eat the recommended number of calories for your weight, height, age, and sex.

Additionally, you should also be staying adequately hydrated, and you’re allowed to drink water, coffee, or tea throughout the day. However, other beverages like diet or low-calorie beverages are not allowed.

Finally, we also recommend eating your meal at the same time every day to ensure your fasting period is consistent.

A Word From Our Nutritionist

It goes without saying that the OMAD diet is one of the most restrictive diets in the world.

You are literally avoiding food for 23 hours every day, only to fill up during a 1-hour period of eating, where you need to consume all of your calories, food groups, and nutrients. That’s a lot to keep track of, and it goes without saying that this isn’t a diet for everyone.

It’s also important to talk about OMAD for what it is – self-starvation. Still, it could have a range of health benefits if you think you’re up for it.

Weight loss, discipline, energy boost, and reduced inflammation – that’s only a few positive things when you are on an OMAD diet.

If you are expecting or breastfeeding, have cardiovascular disease or diabetes, you can’t follow the OMAD as it can be harmful to your health.

Before beginning to eat only once a day, consult with the healthcare professional as this method is not for everyone.

Wrapping Up

The OMAD diet might seem like the easiest way for you to lose weight, but it comes with a number of challenges you might not be prepared for. Expect to be hungry and feel extreme fatigue at first!

However, it becomes easier with time, and it is said that it takes about a week for OMAD to work. Keep in mind that this is not a sustainable diet as it’s very hard to only eat once a day for a long time. 

If you want to try the OMAD diet, begin with the most popular intermittent fasting regimen, which is 16/8. Your body has to be prepared to go without food for an extended period of time.

Written by Thalia Oosthuizen
Thalia has always wanted to be a writer, starting her first local newspaper at the age of 11. She also has enjoyed a passion for health and fitness since a young age, playing many sports through her schooling career, and still enjoys biking, running, and swimming today. She studied English Language at University for 3 years, developing a passion for spelling, grammar, and research. She now has over 10 years of experience writing, proofreading, and editing, and has paired this with her love for health and fitness by writing health content.
The article was fact checked by Rosmy Barrios, MD
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Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 17, 2023
8 min read 1679 Views 0 Comments

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