When I started researching the One Meal a Day Diet (sometimes referred to OMAD), it was the simplicity that drew me to the plan: You eat one meal per day, consisting of whatever you want, typically at your regular dinnertime.
Super unconventional, right?
However, the OMAD is really just an extreme variant of intermittent fasting or a more hardcore cousin of the Warrior Diet. The difference between OMAD and traditional fasting is instead of fasting for the typical window, like 16 hours, you fast for about 23 hours (including the time you spend sleeping).
While the premise sounds a little shady, like a dietary supplement being hawked by a “doctor” on a late-night infomercial, let’s explore the reasoning — and science — on both sides of the debate before we totally write it off.
Why eat only once a day?
Most people cringe at the thought of missing a single meal. Intentionally missing all but one meal, every day, seems excessive and unnecessary. But proponents of OMAD claim a multitude of benefits, including:
- Increased focus and productivity. Who hasn’t hit that groggy 2:30 p.m. slump at the office? OMAD is said to eliminate the sluggishness people feel while digesting their lunch — because there is no lunch.
- Weight loss. It’s extremely hard to be at a caloric surplus when you’re eating one time per day. Even if your one meal is not “healthy” by normal standards, you’re not taking in as many calories as you would if were eating all day long.
- Diet freedom. Forget logging calories or eating out of Tupperware. You free up a lot of mental energy when you don’t have to plan four to six meals per day.
Some follow this eating pattern for religious reasons. But others, including prominent pro athletes like Ronda Rousey and Herschel Walker, voluntarily eat once a day for the long term. Walker claims to have been eating one meal a day, typically a salad and some bread in the evening, for years.
There’s even some historical evidence that the ancient Romans only ate one large meal a day before breakfast began its rise in popularity during the Middle Ages.
My experience with trying OMAD
During my time experimenting with OMAD, I ate once a day multiple times, but never for an extended period of time. My longest streak was five days. Several times, I lifted weights, played full-court basketball, or did other types of strenuous exercise in a fasted state.
Here are my three most important takeaways from trying the OMAD diet:
1. Just because you CAN eat anything, doesn’t mean you should.
Early in my OMAD eating, I got caught up in the childlike glee of being able to eat freely.
Then I realized I had consumed only nachos, wings, and whiskey in 48 hours. This certainly isn’t the optimal fuel for a healthy body.
Yes, part of OMAD’s appeal is the fun of eating what you want, but you should strive to make your one meal balanced and micronutrient rich for the sake of your overall health.
2. It’s probably not great for serious strength training.
I’m an avid lifter. While I didn’t notice any serious loss of strength on OMAD, I wasn’t exactly plowing through the iron either.
If you simply lift for general health and aren’t concerned with performance, restricting your meals probably won’t change anything for you.
But serious lifters who care about increasing their strength over time may want to adopt a less-extreme version of OMAD, like the Warrior Diet or a typical 16:8 eating window.
3. It’s a great way to improve discipline and willpower.
One of the reasons I tried OMAD was to see if I had the mental toughness to prevent myself from eating. It was challenging — hunger is a powerful feeling. On some days I gave in and ate lunch.
But most of the time, I was proud I’d stuck to the diet and felt free to reward myself with a hearty meal. If you believe that discipline is a muscle and yours needs to be strengthened, OMAD is one way to do so, an option that will actually get you in better shape.
What does science say about OMAD’s benefits and risks?
Like lots of health trends, just because people do it doesn’t mean it’s good for you. The research is mixed when it comes to whether or not it’s safe to eat one meal a day.
One 2007 study connects eating once a day to an increase in blood pressure and cholesterol. So if your one meal a day consists of highly processed fried foods or too many simple carbs, you’ll feel pretty bad, even if you’re losing weight.
Other risks of fasting may include:
- feeling extremely hungry or binge eating
- shakiness or physical weakness
- fatigue, or low energy
- brain fog, or trouble focusing
That said, if you have diabetes, long-term OMAD probably isn’t right for you. And of course, you should consult your doctor before drastically changing your diet.
Research that dates to 2005 shows that fasting can improve the body’s resistance to disease by putting cells under a “positive stress,” in a similar way that lifting weights causes tears that make muscle fibers grow back stronger.
Extended fasts where only water ingested have also been linked to a lowered rate of diseases, such as cancer and diabetes, in one 2016 study with mice as subjects.
In a 2018 chart review of 768 medical-facility patients, it was found that limited, water-only fasts did not result in any long-term medical complications.
The general medical consensus is that it’s probably safe for most healthy adults to fast every once in a while. However, the studies noted here reference general intermittent fasting or days of water-only fasting. There are not many studies specifically on the risks or benefits of OMAD.
Does that mean you should?
The answer is different for everyone. Whether or not OMAD is the right fasting diet is something you should discuss with your primary care provider.
When I decided to try OMAD a few months ago I was already doing intermittent fasting, and the idea of losing weight while eating whatever I wanted was appealing. Plus, I liked the idea of challenging myself and pushing through uncomfortable hunger pangs.
Who should not try OMAD?
This is not a diet that can be sustained for a long period of time, therefore, as a Registered Dietitian, I do not endorse this weight loss diet approach.
When it comes to dieting, as a rule of thumb, people should be wary of methods and fads that presents itself as an easy fix to a complicated problem.
The OMAD diet can be extremely dangerous for children or young adults, people with diabetes or hypoglycemia, obesity, or metabolic rate issues, and it may increase the risk for binge eating.Katherine Marengo, LDN, RDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
The bottom line
Eating once a day isn’t as crazy or dangerous as you might think, but it’s not for everyone. Personally, I would not recommend it as a long-term way of eating for weeks or months at a time.
However, one 2016 study links eating one or two meals a day to a reduction in BMI, and some people have great results turning OMAD into a lifelong commitment.
Besides MMA fighter Herschel Walker (mentioned above), another example is Blake Horton, the ripped YouTuber who regularly posts videos of massive meals like chicken taco pizza or a 7-lb burrito of Fruity Pebbles.
Like most people, OMAD was a little too difficult for me to do every day. If you want to try fasting but are intimidated by OMAD, you could consider something more manageable for your daily meal plan, like the 5:2 Diet or the Warrior Diet.
However, I still only eat once a day every now and then, especially when I’m extremely busy or after eating a large dinner the night before. It’s also a great way to practice discipline and challenge yourself.
The key to success with OMAD, like any other diet, is to listen to your body.
Change things up if you notice serious negative effects, noting that it’s okay to be hungry from time to time. You may find yourself reaching new levels of focus and productivity as the pounds melt away.
If not, at least you’ll have fewer dishes to clean up!
Raj is a consultant and freelance writer specializing in digital marketing, fitness, and sports. He helps businesses plan, create, and distribute content that generates leads. Raj lives in the Washington, D.C., area where he enjoys basketball and strength training in his free time. Follow him on Twitter.