As the practice of eating one meal a day has grown in popularity, the questions have poured in. Foremost among them is some variation of the most basic: Is eating one meal a day a good idea? Is it safe? Is it smart? Should you do it? And on, and on.
I’m not here to tell you whether you should or shouldn’t eat one meal a day. That’s a decision for you to make. What I can do is, if it’s something you’re leaning toward, give you some things to consider before trying and some tips for optimizing it.
After all, one meal a day is relatively novel. Six to eight small meals a day is highly novel in the human experience, don’t get me wrong, and I would never advise something like that. But, breakfast, lunch, and dinner are relatively well-preserved across the spectrum of human traditions. Most populations eat at least twice a day. Although individual exceptions exist, few if any populations eat one meal a day in perpetuity.
So, what are some things to consider?
Don’t expect it be optimal for mass gain.
When you’re trying to gain muscle mass, you need to eat. You need to eat more food than you’re used to eating. Calories in need to exceed calories out. Funnily enough, it’s during a phase of desired mass gain that calorie counting really begins to matter. Focusing on the quality of the food you eat is great for inadvertent calorie reduction and weight loss; emphasizing the quantity while maintaining the quality is usually required for desired weight gain.
It’s really hard to eat enough food in one meal to gain weight. Lose fat while maintaining muscle, perhaps even making neuromuscular or efficiency-based strength gains? Sure. But very few get huge eating OMAD.
If that’s your goal, OMAD every day might not be the best option.
Focus on protein.
Protein is the most essential nutrient, biologically-speaking. We can’t make it ourselves. We can only eat it or pull it from existing tissues. For the sake of your health, your physical function, and your aesthetics, you should do the former and avoid the latter.
Protein is also incredibly filling. Your protein intake might not make the cut eating one meal a day. You might eat too little.
Plus, recent evidence suggests that to maximize muscle gain, spreading your protein intake across four meals a day with around 0.4 g protein per kg of bodyweight per meal is the best or “optimal” method. That’s mostly based on studies in “normal” people, not “weirdos” eating grass-fed meat or going keto or (gasp) eating a single meal a day. I suspect there’s some level of adaptation in us “weirdos” that improves our ability to utilize all the protein.
On paper, there’s a lot riding against you getting enough protein.
In reality, you will absorb all the protein you eat, even if it’s a ton in a single sitting. The real trick is making sure you eat enough—that can be hard.
Don’t do it every day.
This is my general advice to everyone who wants to eat one meal a day. Doing it every single day is hard. It makes it tough to hit your required protein. It makes it hard to get enough calories. It can wear on your social relationships. It can be stressful on your body.
But if you do OMAD two or three days a week, suddenly the stress becomes hormetic. Instead of being something that wears on you, it’s something that forces an adaptation. Suddenly you’re cycling calories—high one day, low the next—and life tends to work better when it cycles back and forth.
Do it on rest days.
Workout days? Maybe eat more frequently. Maybe do a shorter eating window with two or three meals shoved in there. You’re demanding a lot from your body, and one meal simply may not cut it.
But rest days? OMAD to your heart’s content. The break from digestion and nutrient infusions will actually help your body recover from the training. In fact, OMAD on rest days, and two to three MAD on training days might be the best possible way of doing it.
Take some electrolytes in the morning.
Why? Just like fasting and going keto or very low-carb for the first time, OMAD places a greater demand on your electrolytes. It lowers insulin, which depletes sodium and then potassium and magnesium. A big glass of sparkling mineral water with plenty of fresh lime or lemon juice and a spoonful of salt and maybe a scoop of magnesium powder should do the trick. Gerolsteiner is the most mineral-rich of the readily-available waters (and it’s delicious). That’s my go-to for days when I’ll be fasting or getting back into keto after a time off, and OMAD operates along similar lines.
It doesn’t contain enough calories to nullify the OMAD, and it will keep you energized and your stores topped up. You’ve also got Robb Wolf’s electrolyte mix if you don’t want to mix your own. He always does his homework.
Be careful if you’re a woman.
It’s just a reality that women—in general—are more vulnerable to caloric insufficiency. For the reasoning and mechanisms, read this post on women and fasting (OMAD is basically a daily fast). Some people might take offense at that, but it’s the truth and I care about all my readers. I want you all to succeed. I don’t want you to try something that not only doesn’t work, but also actually harms you.
I’ve seen OMAD work for ladies, but I’ve seen it fail more than not. What seemed to work was not doing it daily (see previous section), not going too low-carb, and making sure to eat enough food.
Coffee can be a lifesaver on OMAD. You get up and, instead of wolfing down breakfast, drink a cup of coffee. This upregulates your fat-burning and keeps you going ’til your single meal. Thousands of people probably couldn’t manage intermittent fasting without coffee, and the same goes for OMAD. Well, maybe they could, but it certainly makes it easier. That’s hard to argue with—and I won’t try. I’m a big fan of coffee when I fast.
However, coffee also has the potential to spike cortisol and exacerbate stress. It can make the OMAD work better in the short term but worse in the long term.
Don’t do the “drink-coffee-when-you’re-bored-and-thinking-of-food” thing. Don’t drink it throughout the day. If, by the time dinner rolls around, you’ve had a dozen cups of coffee, you’re doing it wrong. Are those last eight cups really helping your productivity and energy levels? I doubt it.
Wait a couple hours to drink coffee in the morning (if you can). There’s a natural cortisol spike upon waking, and drinking coffee at the same time it’s spiking naturally will elevate cortisol even further and shortchange the boost you get. Better to wait til 9 a.m. or so.
Drink green tea or matcha or take L-theanine with your coffee. The L-theanine (present in green tea and matcha) synergizes with the caffeine, limiting the cortisol response, reducing jitters, and improving the boost to cognition.
OMAD has the potential to really help a lot of people get a handle on their eating. But there’s also the chance for it go really, really wrong. I hope these seven items help nudge you in the right direction.
If you have any further input or questions, let me know down below. How do you do OMAD? What tips do you have for others who want to try? What do you wish you knew when you started?
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.