For people who just love food, the idea of OMAD (one meal a day) sounds like a living nightmare.
However, like other fasting-type diets, people who do it swear by its effectiveness, with claims that it boosts your metabolism, accelerates fat loss and even helps prevent certain diseases.
Now if you’ve been around this blog long enough and you see how this article has started, you can probably also guess where it’s going.
But what if I told you that I, a sports dietitian, have and still do participate in the practice of OMAD?
While you collect yourself from the news and before we go any further though, let’s talk about what the OMAD diet is.
What is OMAD and How Do You Do It?
The “rules” of OMAD vary depending on the person, but the general idea is to fast for 23 hours a day and then eat all of your daily calorie and macro requirements in the remaining hour.
Supporters of the diet also urge participants to eat the meal around the same time each
day. It doesn’t have to be the same hour, but within the time frame. So, if you decide to have your meal at 9am, you want to have meals on subsequent days around 8am - 11am.
When I am doing OMAD, like many, I find it most manageable to have my meal in the evening so I’m not trying to sleep on an empty stomach. Thus, I’d normally have my large meal between the hours of 7-10pm.
I know it sounds ridiculous, but I’m a night owl what do you want from me.
Essentially, OMAD is a different breed of intermittent fasting. However, OMAD could be considered more strict and challenging to follow. IF allows you to eat as many meals and snacks as you want as long as you stay within your calorie/macro goals and keep the eating stints within your designated “feeding window.”
With OMAD, though, you get one meal and that’s the ball game.
So, what are the benefits of subjecting yourself to such a practice? Let’s look at the science.
The Benefits of OMAD
Unfortunately for OMAD disciples, most of the positive research around the OMAD diet has been done on animals and human studies exploring OMAD have too many confounding principles to reliably connect OMAD with benefits like longer life and disease prevention.
It’s not all bad news, though, kids.
There has been some promising research on OMAD’s effectiveness for fat loss. Again, though, if you’ve been on this blog long enough, you know I’m not gonna BS you.
Whether you’re a carnivore, vegan, an intermittent faster or a king of ketosis, it doesn’t matter how flashy or extreme the diet is. As long as it can keep you in a consistent calorie deficit, you WILL lose weight regardless of the food you eat or how often you eat it.
That said, fasting diets like OMAD have been shown to be effective at helping you lose fat. Many of these studies also showed they helped with blood sugar control and insulin sensitivity in those with insulin resistance. However, we also know that weight loss is also associated with better insulin response, so this effect is likely not attributed to a magical property of fasting or OMAD itself.
And the ability to maintain a weight-losing calorie deficit on OMAD isn’t hard to figure out. One study that had a group of subjects eat 3 meals a day and another group follow OMAD found that the OMAD group was the only group that lost weight.
Before we start pumping our fists, though, further reading reveals that the OMAD group had much more difficulty following the diet. They reported that they never got used to the feeling of being hungry all day. They also shared they struggled to eat an entire day’s calories in one sitting and, even after the meal was finished, they experienced an uncomfortable feeling of “extreme fullness.”
The biggest takeaway, though, is that after 2 months of participating in the study, the OMAD group only lost about 4 pounds, which is about a half a pound a week. While this isn’t insignificant, it’s not exactly numbers to write home about. Especially if you are part of the group who found the practice unpleasant to adhere to.
Pros and Cons of the OMAD Diet
Many health and nutrition professionals express concern over the safety and realism of the OMAD diet. However, it can also be a useful method if followed under the right supervision. So let’s take a minute to go over some downsides and perks of OMAD.
Pros
Great for Busy People and Big Eaters
The reason I started doing OMAD despite the practice being slightly antithetical to the balanced eating patterns dietitians teach is because it simply worked out for my schedule. I work nonstop during the day without a lot of time to make the meals I like to eat, which are fresh, home cooked meals that take a large chunk of my work day to put together.
I’m also a girl who can’t just eat a little bit. Your girl HOUSES food, especially when it’s super delicious. I quickly found out that if I ate 3 meals a day like that, I’d very soon find myself shopping for a larger wardrobe.
So, for people with similar proclivities, OMAD may be the answer to help control overeating and to remove the stress of having to eat on “a schedule.”
Weight Loss
Even though subjects of some OMAD studies have found the diet difficult to follow, if you have the willpower, studies do show it can help you lose weight.
Indeed, if you have high calorie needs, it can be pretty difficult to eat 2,000+ calories all in one sitting which will inevitably lead to a calorie deficit. The alternative would be eating 3 meals a day, but having to restrict portions and eat low calorie foods, which could be more difficult weight loss plan to adhere to for some.
Cons
Probably Not Good for You
The biggest problem with eating only one meal a day is that, in order to meet calorie requirements, most people drastically reduce low-calorie, high-volume foods.
Like fruits and vegetables.
The consumption of more plants is associated with longer life, lower risk of chronic disease, better energy, gut health, etc., but it’s also not super conducive to an OMAD diet. Thus, following the diet could leave you missing out on key nutrients, especially if not planned out in conjunction with a registered dietitian.
This is compounded with the fact that the restriction can make you extremely hungry throughout the day, especially when you are just starting out on the diet. So much so that, again if not well thought out, it can be easy to binge on high-calorie junk foods that you feel you’ve “earned” after your long bout of fasting.
Not Sustainable and Disordered Eating Risk
As we talked about with the OMAD study, many participants expressed how difficult the diet was to follow compared to the group who consumed 3 meals a day with the same number of calories.
Now ya’ll. This is common sense.
Of COURSE a diet that allows you to eat more often to satisfy your hunger compared to one that forces you to rely on sheer willpower for 23 hours out of the day is going to be easier to follow.
And what are the diets that work the best? The ones that you can follow the longest.
Now, it’s not to say you can’t be a part of that special breed of tough-as-nails people who can ignore your hunger cues, the low energy, brain fog, and other side effects that come with fasting for most of the day.
However, given that studies have shown that fasting is no more effective at promoting weight loss than eating 3 meals a day of the same calorie content, it doesn’t make a whole lot of sense to choose the option that makes you suffer for the same result.
Finally, this style of eating is dangerous for those with a history of disordered eating patterns and can cause a relapse which is something to keep in mind when considering weight loss strategies.
It Doesn't Promote Muscle Growth
As a sports dietitian, I absolutely cringe when athletes and people I just know personally tell me they are doing OMAD while also trying to gain or maintain their muscle mass.
Firstly, you need to be in a calorie surplus to put on muscle and eating more calories than you’re burning with just one meal a day would be extraordinarily difficult.
Not only that, studies have shown that the body puts on muscle the most optimally when adequate protein is consumed (which is difficult to fit into one meal due to protein’s influence on satiety) and when this protein is distributed evenly throughout the day.
Skipping meals also puts you at risk of forcing your body to begin breaking down muscle tissue for energy. So, you’ll lose weight, but if you’re trying to keep your muscle mass in the process, skipping nearly an entire day of eating is pretty counterintuitive.
So, Should You Try OMAD?
Short answer? Only if you have a large amount of confidence in your willpower. To take it a step further, it’s strongly recommended that you start the diet under the guidance of a registered dietitian.
Eating one meal a day is nuts, let’s face it. And by doing so you could put your health at risk without a nutrition professional to help you make sure you can get everything you need in a single meal, especially if you end up following the diet long term.
Ditto this recommendation if you have specific body composition goals, such as losing fat, but preserving muscle. You can’t just pick up and do OMAD without very specific macronutrient calculations and the foods to keep in your rolodex to hit these numbers in a single feast.
The Bottom Line?
OMAD is something you can give a try if other forms of dieting, including traditional, 3-meal-a-day dieting, just isn’t working for you. It’s not recommended under any circumstance if you have a chronic disease like diabetes, are pregnant, or have a history of disordered eating.
If you’re a busy professional or work an unconventional job (such as overnight shifts) that doesn’t allow for a normal eating pattern, OMAD could also be useful under the right supervision.
All of that hooey about it helping you to detox, live a longer life, and blah blah blah though? Throw that in the garbage where it belongs. It’s just another calorie deficit weight loss tool. No more and no less.
If you are looking for recipes or meal plans to get your body comp where you want it to be, check out my resources. If you’re good on all that and just need your macros calculated by a sports nutrition expert, I got you covered there too.
Stay safe out there kids.
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