|February 4, 2020

OMAD: Should You Do the One Meal a Day Diet?

By Emma Rose
Reviewed by Emily Gonzalez, ND for Scientific Accuracy

OMAD: Should You Do the One Meal a Day Diet?

  • Eating one meal a day, also called the OMAD diet, is a style of intermittent fasting with big benefits for your brain and body.
  • One meal a day fights aging, boosts metabolism, improves health, protects against disease and simplifies meal preparation.
  • Eating only one meal a day can be difficult, but there are ways to ease in slowly and even make it easier.
  • Bulletproof Coffee gives you sustained energy and satisfies hunger without breaking your fast. Get everything you need to make it with a Bulletproof Coffee Kit.

Intermittent fasting is skyrocketing in popularity as modern research uncovers its health and weight management benefits. Extending the time between meals can profoundly impact your brain and help your body work even better. One intermittent fasting style you may be hearing a lot about is an all-day fast with the exception of one meal a day. People call this the OMAD diet.

The OMAD intermittent fasting schedule aims for a 23:1 fasting ratio, which gives your body 23 hours each day to reap the benefits of a fasting lifestyle. If you’re looking to burn fat, improve mental resilience and simplify the time you spend on food, eating just one meal a day could be the key to taking you to the next level.

Read on for a quick guide to starting the one meal a day diet, OMAD benefits and the pros and cons you need to know before you decide if this fasting style fits you. Keep in mind that fasting is not a good idea for those with a history of eating disorders or disordered eating.

What is OMAD and how does it work?

Alarm clock and plate on blue background

When you’re on an OMAD diet, you eat all of your daily calories in just one meal each day. You typically fast for the remaining 23-ish hours. One-meal-a-day fasting lets you reap the health benefits of fasting while also simplifying your schedule (you know, if meal prep and eating feels bothersome to you).

For most people, between 4-7 p.m. is an ideal time to break the fast. This window gives you fuel when you need it, time to eat with friends or family and enough time to digest before heading to bed.

Intermittent fasting schedules such as OMAD supercharge your body by activating stress response pathways that boost mitochondrial performance, autophagy and DNA repair in your cells, as well as triggering beneficial metabolic changes and preventing chronic disease processes.[1] We’ll talk more about the benefits of OMAD below.

Related: The Complete Intermittent Fasting Guide

How to start the one meal a day diet

Cup of cashew nuts

OMAD can be a pretty extreme intermittent fasting schedule, especially for newbies. Avoiding food for 23 hours a day takes a lot of extra effort, and creating a situation that stresses you out can undo some of the powerful benefits of fasting.

The goal with one meal a day isn’t to feel like you’re punishing your body or suffering through a challenge. A successful transition to intermittent fasting means training your body to handle a different, yet sustainable routine.

If you want to start slow, here are a few tips:

  1. Introduce intermittent fasting every other day, with small snacks after workouts.
  2. Start by fasting in shorter durations. Get comfortable fasting for 16-20 hours at a time, and slowly build up to fasting for 23 hours a day.
  3. You can also try one 23:1 day, then add more OMAD days into your weekly routine. As with any style of fasting, it’s important to see how your body responds and find what works for you.

The toughest thing about fasting isn’t trying to power through your hunger—it’s catching yourself before you mindlessly grab a snack and pop it in your mouth.

Related: Constantly Snacking? Nutrition Expert Shares How to Eat Mindfully

Benefits of one-meal-a-day fasting

Outline of person's head with lightbulb

Long periods of fasting benefit your body by gently stressing your cells, making them more resilient.[2] It’s a process called hormesis—using stress to make you stronger.

In an episode of the Bulletproof Radio podcast, Brad Pilon, author of “ and a top expert on the science of fasting, compares the stress of fasting to the benefits your body receives from a weight training session. “The body is introduced to small stress that actually has beneficial effects,” he says. “If the stress were to get too large, it would become negative to the human body. A small amount of stress allows the body to learn to adapt.”

Fights the effects of aging

The OMAD diet and other intermittent fasting styles activate autophagy, your body’s clean-up mode for damaged cells, toxins and waste.[3] Autophagy also occurs in neurons of your brain, part of why intermittent fasting diets have been shown in rodent studies to fight age-related neurological disorders such as Alzheimer’s, Parkinson’s and stroke.[4]

Boosts metabolism

In rodent studies, intermittent fasting has been shown to have a beneficial effect on lowering blood sugar and increasing insulin function.[5] Translation: Animal studies point to the fact that fasting may have profound effects on your metabolism.

Speaking of fat-burning—if you want another way to satisfy hunger, burn fat and stay sharp, add MCT oil to your routine. Learn why MCT oil is one of our top keto supplements.

Improves health and protects against disease

Animal studies have linked intermittent fasting to improvements in weight loss, asthma, cardiovascular disease and inflammation, as well as protection against cancers, neurodegeneration and diabetes.[6][7]

Simplifies meal prep

Among fasting styles, OMAD fasting brings some unique benefits of its own. If you’re only eating one meal, you can leave behind the stress of finding healthy meals at work, on the go or at restaurants throughout your day. Eating OMAD means you only have to plan for one meal a day, letting you sleep through breakfast and simplifying the grocery plan.

When you eat, you’ll eat less

OMAD can also make it easier to manage your weight through natural calorie restriction. You’ll find you aren’t able to comfortably eat your entire day’s calories in one sitting, but you’ll still feel like you’re indulging in a large meal.

Heads up: This benefit is a double-edged sword. Prolonged calorie restriction can actually slow down your metabolism, reversing some of the benefits of intermittent fasting. If you’re struggling to eat enough, don’t do OMAD every day, or experiment with other styles of intermittent fasting.

Related: Want to Try a Fasting Diet? Here’s How to Choose the Right One

You can make it easier

Here are two things you can do that make an OMAD diet easier.

  1. Limit the amount of carbs in your diet. When you eat a lot of carbohydrates, your body stockpiles glucose as glycogen. This means it will take a lot longer for your body to shift into ketosis, or fat-burning mode, when you are fasting. Switching to a keto diet can help make your fast easier.
  2. Drink a cup of Bulletproof Coffee in the morning to reap the benefits of fasting without feeling hangry all day. What? But that’s eating! Yes, but the quality fats from grass-fed butter and Brain Octane MCT oil boost your ketone production and metabolic rate.[8] Read more about how Bulletproof Coffee makes fasting easier.

The bottom line: Like other styles of intermittent fasting, the OMAD diet is a way to clean up damaged cells, boost your metabolism and maybe even support healthy aging. Because you’re only eating one meal a day, you get back time you would have spent cooking, and you’re eating fewer calories while still feeling satisfied with a big meal.

OMAD tips and tricks (and knowing when to stop)

Woman on bed with pillow over stomach

Fasting for 23 hours is not easy. Getting all your nutrition in one meal is even more challenging. And of course, your body can give you signals that it’s time to quit. Here are some tips to adjust to the OMAD diet and red flags to watch out for. Before you make any big changes to your diet and routine, talk to your doctor.

  • Make your one meal count: Make sure your meals are balanced, diverse and cover a full range of macro and micronutrients. Filling up too fast on one food group means missing out on the other nutrients you need. If you’re following a ketogenic diet in addition to an OMAD schedule, make sure to be mindful of your macros, and keep your large meal under your carbohydrate limit.
  • Fudge the timeline: OMAD also doesn’t need to be a strict 23:1 fasting:eating ratio. If it’s more comfortable for you to spread your large meal out over more than an hour, try it! If your body is screaming for food at hour 22 with major hangries after a big workout, go ahead and eat. It’s more important to maintain your composure and keep your life on track than it is to stick to a strict timeline.
  • Listen to your body: Even with balanced nutrients, some bodies simply don’t agree with extreme 23-hour fasting, and that’s okay. If you have a faster metabolism, frequently deal with mental stress or enjoy intense workouts, don’t force a schedule without listening to your body’s cues. If your body is stressed from fasting, it will release extra adrenaline and cortisol. If you have restless sleep or wake up unintentionally early, or if you’re feeling sluggish, weak or constantly tired, your body is telling you it needs more energy, more often.
  • Recognize when to stop: Pilon recommends using intermittent fasting infrequently because “the leaner you are, the less frequently [you need to fast] …You’ve accomplished what you’re trying to do. Now you’re basically fasting for health benefits and as a way to keep your weight in check.”
  • Transition out mindfully: Transitioning out of an OMAD schedule can pose its own problems as well. Restricting food all day can make you feel like you want to eat the biggest meal possible, as quickly as possible. But this mindset can do more harm than good, particularly if you binge on junk food or have a history of disordered eating. When you break your fast, fill your plate with nutrient-dense foods that support your health and wellness goals. If you’re struggling to balance nutrition and fasting, it’s okay to take a step back.
  • Women should pay extra attention: Studies show that intermittent fasting can mess with women’s insulin response.[9] Additionally, rodent studies show that fasting too much can cause the brain to suppress reproductive hormones.[10] If you notice negative changes in how you feel, or shifts in your cycle, see a doctor.
  • Fasting can cause more than just physical stress: Restricting yourself to one meal a day can also be taxing to your mind. Take care of your stress levels by practicing yoga, meditating, exercising or whatever helps you find your zen, and remember that more difficult fasts do not equal better results. Check in with yourself regularly to see if your schedule feels right, and remember that it’s okay to try different styles of fasting—or not fast at all.

The bottom line: Be Bulletproof on the OMAD and pay careful attention to your body. Make sure your meal provides all the daily nutrients you need. It’s okay to fudge the timing if you can’t make it to hour 23 or eat your whole meal in an hour. Above all, take care of yourself. Fasting is a tool to support your mind and body, but it’s not the only way to live a healthful life.

Read next: Can You Take Supplements While Fasting?

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