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What Happens if you Only eat one Meal a Day?

By Liam McAuliffe Updated on

OMAD is the acronym for One Meal a Day, and it means just that: fitting all of your calories into a one-hour eating window. We like to call this intermittent ‘feasting.’ It’s one of the more intensive types of intermittent fasting and part of Dr. Kitlz’s three pillars of health and wellness. As a dietary practice that’s growing in popularity, you may be wondering, what happens if you only eat one meal a day? 

In this article, we’ll explore what happens to your body and mind if you only eat one meal a day, and how to practice OMAD in the most nourishing and sustainable way. 

Table of Contents

The Key To Getting Positive Results from Eating Only One Meal a Day

Eating one meal a day doesn’t automatically mean that you will get all of these health and wellness benefits.

When it comes to the question, “What happens if you eat only one meal a day?” the answer ultimately depends on the foods you eat during your 1-hour eating window. 

A well-formulated and nourishing OMAD meal is based around the healthiest and most nutrient-dense foods in the world, including: 

It’s also important to dial in your OMAD macros and calories so you’re getting between 1500 and 2000 calories a day. 

OMAD is not about restricting calories and starving yourself. In fact, it’s better to consider weight loss as a benign side effect of a much more holistic health and wellness transformation and not the goal. 

This OMAD 7-Day meal plan offers a more detailed example of what your well-formulated OMAD meals can look like. 

Now that you know more about what types of food support an OMAD lifestyle, we’re ready to explore what happens to you if you eat only one meal a day. 

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What Can Happen if You Eat Only One Meal a Day

Eating only one meal a day while adhering to a diet based on fatty, whole, animal foods can catalyze numerous benefits. 

The various health and lifestyle benefits of OMAD include: 

  • Simplifying your relationship to food and eating
  • Creating more time and mental space for other interests, relationships, personal growth, and career goals
  • Promote gut and digestive health
  • Stimulate cellular renewal (autophagy)
  • Lose excess weight
  • Reduced inflammation and autoimmune disorders
  • Improve hormonal sensitivity and balance

Let’s dive deeper into a few of these key OMAD outcomes. 

Aligns Your Modern Eating Habits with Evolutionary Eating Patterns

Eating one meal a day runs contrary to a standard American diet of three meals a day with snacks in between. 

Feasting on large meals and fasting in between was likely the norm for humans for nearly 2 million years of evolution up to around 10,000 years ago when we domesticated plants.  

That’s because humans were apex predators that feasted on successful hunts or large prey, then fasted until the next hunt. Remember, there was no refrigeration, so when the food was fresh you had to eat it, and it didn’t stay fresh for long [1]. 

And even in many ancient “civilized” societies, fasting was the standard. For example, the Romans believed it was healthier to eat only one meal a day. “They were obsessed with digestion, and eating more than one meal was considered a form of gluttony,” remarks food historian Caroline Yeldham [2].

From a biological evolutionary perspective, the Romans were on to something. 

Entering a fasted state can activate various beneficial responses: our brains work faster with greater focus, our blood vessels dilate, and our muscles become more resistant to lactic acid build-up [3].

For our ancient hunter-gatherer ancestors, these responses amounted to being better hunters, which seems obvious when considering that the hungrier we are, the better we need to be at obtaining food. 

On the other hand, when we’re constantly eating and essentially overfed, we gain excess fat and move and think more slowly [4]. 

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OMAD May Help you Reduce Inflammation

Across the world, 3 out of 5 people die from chronic inflammatory diseases, including stroke, respiratory diseases, heart disorders, cancer, obesity, and diabetes [5].

Eating only one meal a day may help you reduce inflammation. Fasting has been shown to reduce inflammation by attenuating proinflammatory cytokines in immune cells, while allowing your gut lining to regenerate [6] [7] [8]. 

Healing the gut lining can be critical to controlling inflammation when considering that leaky gut AKA intestinal permeability, allows plant toxins like lectins to cross into the bloodstream, resulting in inflammation and exacerbation of arthritis in various parts of the body. 

Researchers suggest that fasting’s ability to limit inflammation is a key factor in rodent studies showing that eating less frequently can increase lifespan by as much as 80 percent [9].

Combining OMAD and a high-fat, low-carb ketogenic diet (speed keto) can increase the anti-inflammatory benefits of both practices. Ketones–the energy molecules released during ketosis–nourish your mitochondria and promote new mitochondrial generation in an anti-inflammatory, anti-aging process called mitophagy [10].

You can further reduce inflammation by avoiding Inflammatory foods

Only One Meal a Day May Support Mood and Mental Health

Eating only one meal a day can increase the production of neurochemicals and hormones associated with improved mental health and mood. 

In a fasted state your body produces a hormone called Brain-Derived Neurotrophic Factor (BDNF). Harvard neuropsychiatrist John J. Ratey calls it “Miracle-Gro for the brain.” Higher BDNF levels are associated with better mood, enhanced cognition, and more creativity [11].

Other studies show that low levels of BDNF are correlated with higher rates of depression-related suicide [12][13].

The anti-inflammatory effects of fasting can also have a positive effect on mental health and mood. Depression is linked with higher levels of inflammation while fasting, and autophagy (cellular renewal resulting from fasting) are both shown to reduce inflammation [14][15][16].

Studies using mice show that a long-term intermittent fasting results in significant improvements in learning, memory, and cognitive functioning [17].

A 2021 analysis of various studies looking at fasting effects on mental health found that it can reduce stress, anxiety, and depression, especially in non-pathological i.e. mild symptoms [18]. 

When eating meals based around highly satiating keto foods that fuel you through the day, you avoid the post lunch slump, and the need to boost energy with caffeinated drinks that can increase anxiety

Combine eating only one meal a day with a mid-afternoon power nap to further boost your mood, creativity, and mental sharpness. 

Eating Only One Meal a Day May Slow Aging

What happens if you eat only one meal a day? You might live longer and feel younger. 

One study found that fasting for 24 hours boosted anti-aging hormones like human growth hormone (HGH) by between 1300 and 2000 percent [19]. 

HGH plays a key role in structuring muscle fibers, connective tissues, and the skin [20].

A 2021 study on fruit flies, with which humans share a remarkably similar DNA, found that a 20-hour fast regimen extended lifespan by 18% for females, and 13% for males. 

However, researchers highlight that the timing of the fast was critical: Longevity increased only for the flies that fasted during the night and broke their fast around midday. For the flies that fasted all day and ate at night, there was no increase in lifespan [21]. 

These findings suggest that aligning your one meal a day with your circadian rhythm by eating around lunchtime may be important for unlocking its anti-aging benefits. 

Studies looking at alternate-day fasting in older people show that it reduces measures of age-related frailty [22]. 

Eating Only One Meal a Day Frees Up Time and Mental Space

Imagine a life in which your desires, logistical bandwidth, and time aren’t constantly hijacked by finding, preparing, and eating food. This freedom is one of the most powerful but least talked about things that happen if you eat only one meal a day. 

OMAD can help free you from distractions that steal time and energy from the long-term goals, pleasurable hobbies, self-growth practices, and relationships that truly feed your heart and mind. 

It’s important to emphasize that OMAD only brings freedom when you fuel up on a full load of calories from nutrient-dense whole foods. Ordering half the menu at McDonald’s will make you sick and sad and crave nutrients whether you eat it all at once or multiple times during the day. 

OMAD Diet Foods

Your one meal a day will be a feast that provides at least 1500 calories. 

The following food chart will help you formulate a robust meal plan. 

For more guidance, check out our 7-Day Omad Meal Plan

RuminantsPorkPoultryfishseafoodOrgan meatsWild meatsfatEggsDairyFruits and Veggies




All typesChicken



Game hen










Arctic Char

























Bone Marrow














Chicken eggs

Duck eggs

Goose Eggs

Ostrich eggs

Quail Eggs




Creme Fraiche






Sweet potato

Russet Potato








What Happens if You Eat Only One Meal a Day? The Takeaway

Eating only one meal a day is an intermittent ‘feasting practice’ that can offer numerous benefits. 

One of the keys to understanding the benefits that happen if you eat only one meal a day is how the practice aligns us with our evolutionary eating patterns. 

Studies show that a fast and feast cycle can reduce inflammation, stimulate cellular regeneration and renewal, increase beneficial hormones and HGH and BDNF, rebalance your microbiome, help heal your gut while supporting mood, and mental health, and enhance cognition. 

The key to unlocking the benefits of OMAD is to feast on nutrient-dense whole foods that meet your daily caloric needs. 

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