OMAD: Should You Do the One Meal a Day Diet?
By: Emma Rose
Intermittent fasting to boost performance and weight loss is skyrocketing in popularity, as modern research uncovers the benefits behind this ancient health practice. One type of intermittent fasting style on the rise is one meal a day, or the OMAD diet. Fasting is a powerful tool for modulating your body’s performance, and not eating for anywhere from 16-48 hours (or longer) can profoundly impact your body and brain.
Types of intermittent fasting styles range from calorie restriction, to cycling between regular and fasting days, to limiting the times in a day that you can consume food.
The OMAD intermittent fasting schedule aims for a 23:1 fasting ratio, giving 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 your keto or Bulletproof Diet to the next level.
Read on for a quick guide to starting the one meal a day diet, OMAD benefits, plus the pros and cons you need to decide if this fasting style fits you.
(There are infinite ways to incorporate fasting strategies into your diet. Get the scoop on how to get started with intermittent fasting here.)
What is OMAD and how does it work?
OMAD is a form of intermittent fasting, the practice of cycling in and out of periods of eating and not eating. Different intermittent fasting styles range from fasting one day each week, to restricting food to a shortened period each day. OMAD is a popular form of intermittent fasting that shrinks your eating window even more than usual.
In this case, you eat all of your daily calories in just one meal each day — typically fasting for the remaining 23-ish hours. One meal a day fasting lets you reap the health benefits of fasting, while hugely simplifying your schedule (you know, if meal prep and eating feels bothersome to you). Between 4-7PM is an ideal time to break your fast, giving you fuel when you need it, a time to eat with friends or family, and enough time to digest before heading to bed.
From an evolutionary standpoint, humans aren’t meant for three scheduled and square meals a day. Your ancestors developed powerful adaptations to keep their bodies and brains performing at high levels, even when food was scarce. 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.
If you’re a woman, you may have different needs when it comes to intermittent fasting. Read up on Bulletproof intermittent fasting for women here.
How to start the one meal a day diet
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 from fasting.
Here, the top three tips for transitioning into a one meal a day schedule, and finding the right balance for your body:
Cut back on carbs
To set yourself up for the best intermittent fasting results and the least crankiness: limit the amount of carbs in your diet. When you eat a lot of carbohydrates, your body will stockpile glucose as glycogen — this means it takes a lot longer for your body to shift into ketosis, or fat-burning mode, when you are fasting. Limiting your starches and fruit by following the Bulletproof Diet or eating keto will curb your hunger and keep your body feeling satisfied longer without the ups and downs of sugar crashes.
Read more: How keto and fasting work better together
Ease into 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 fasting is new to you, try a gradual transition through intermittent fasting schedules. Some people may need to introduce intermittent fasting every other day, use small snacks after workouts, or start with shorter fasts, such as fasting for 16 or 20 hours a day as you build to a 23:1 OMAD schedule. If you’ve done full-day fasts before, you can try adding them more regularly into your weekly routine as you build up to everyday OMAD.
As Brad Pilon, author of “Eat Stop Eat,” and a top expert on the science of fasting, explains in an episode of the Bulletproof Radio podcast, “The hardest part of fasting wasn’t the not eating because I was hungry, it was the not eating because of my habits…It took a while to get used to letting go of my trained eating styles.”
But first, coffee
Wait, coffee and fasting? This Bulletproof fasting hack can be applied to any fasting schedule, and includes adding a cup of of Bulletproof Coffee to your morning. If you’re an athlete, stressed student, hectic parent, or busy entrepreneur, you may need a little extra boost to keep you feeling powerful through a day of fasting. The healthy fats from grass-fed butter and Brain Octane Oil give you a stable current of energy that sustains you through the day while boosting your ketosis and metabolic rate. This can be especially beneficial for women whose bodies and hormone pathways are designed to fight famine mode to support reproduction. Remember, the goal is to find how one meal a day works for your body, not to judge yourself for hitting “full-on” fasting.
Read more: Bulletproof fasting with coffee
Benefits of one meal a day fasting
There’s a reason fasting diets have around for centuries, and are making a resurgence today. Long periods of fasting benefit your body by gently stressing your cells, making them more resilient. It’s a process called hormesis — using stress to make you stronger.
Pilon compares the stress of fasting to the benefits your body receives from a weight training session, “The body is introduced with small stress and that small stress actually has beneficial effects. If the stress were to get too large, it would become a negative on the human body. A small amount tends to allow the body to learn to adapt.”
The OMAD diet, or other intermittent fasting styles also activate autophagy, your body’s clean-up mode for damaged cells, toxins and waste. This autophagy also occurs in neurons of your brain, part of why intermittent fasting diets fight age-related neurological disorders such as Alzheimer’s, Parkinson’s and stroke.
Fasting also has profound effects on your metabolism. Not only does it reset your tolerance to hunger, and let you burn fat longer, intermittent fasting has a beneficial effect on lowering your blood sugar and increasing insulin function, both factors in preventing obesity and diabetes.
Other human studies have linked intermittent fasting to improvements in weight loss, asthma, cardiovascular disease and inflammation, while intermittent fasting in animal studies protect against cancers, neurodegeneration, and diabetes. 
Many fasting variations can achieve these outcomes, but OMAD fasting brings some unique benefits of its own. To begin with, OMAD definitely simplifies things: Leave behind the stress of finding healthy, Bulletproof-approved meals at work, on the go, or at restaurants throughout your day. Eating just one meal a day means prepping just one meal a day, letting you sleep through breakfast prep time, and simplifying the grocery plan. OMAD also adds an extra benefit for weight loss through more natural calorie restriction. Many people find it impossible to comfortably eat a regular day’s calories in one sitting, but still feel like they’re indulging in a large meal.
Read more: The benefits of intermittent fasting
Potential OMAD downsides (and how to hack them)
While one meal a day might simplify your planning, it still requires planning. If your fast leaves you feeling desperate at hour 22.5, you may be tempted to binge on satisfying junk foods as soon as your meal begins. Avoiding the temptations of hunger takes some careful considerations.
Make sure you 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, and there’s no second meal later in the day to make up for it.
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! Additionally, if you’re planning on following a ketogenic diet in addition to an OMAD schedule, you still need to be mindful of your macros, and make sure your large meal is staying under your carbohydrate limit.
Even with balanced nutrients, some bodies simply don’t agree with extreme 23 hour fasting, and that’s OK. One pitfall of an OMAD lifestyle is trying to force a schedule without listening to your body’s cues, especially if you have a faster metabolism, frequently deal with mental stress, or enjoy intense workouts. If your body is stressed from fasting, it will release extra adrenaline and cortisol. Restless sleep or waking up unintentionally in the early morning are signals from your body that you’re doing too much. If you’re feeling sluggish, weak, or constantly tired, your body is telling you it needs more energy, more often. All bodies are different, and you can still reap the benefits of fasting with a gentler schedule that fits your body’s pace.
If you notice these symptoms, tell your body that it’s nourished and safe by planning meals around diverse nutrients, healthy proteins and plenty of fat. You can also try cutting down your fasting to once or twice a week, or a more moderate daily schedule, and building up from there. Depending on your goals, Pilon recommends using intermittent fasting less frequently, “If you’re fasting…then the leaner you are, the less frequently [you need to fast]… because you’ve earned it. You’re lean. 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.”
Transitioning away from an OMAD schedule can pose its own problems as well, as your body adjusts to wanting huge meals when you sit down to eat. Either way, take time to listen carefully to how your body responds, and experiment to find what works for you.
Restricting yourself to one meal a day can also be taxing on your mental stress. Take care of your stress levels by practicing these top hacks for stress relief, and remember that more difficult fasts do not equal better results. Check in with yourself regularly to ask if your schedule feels right, and make sure it doesn’t lead to an unhealthy relationship with your body or your food.
Still not sure if OMAD is the right diet for you? Learn more about other fasting diets here.
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