The OMAD Diet Isn't As Healthy As You Think It Is. Here's Why

Have you heard of the OMAD diet? If not, and you're wondering if we really need one more fad diet, or one more acronym, well, you make a good point. And the OMAD — which stands for "One Meal a Day" — is neither the diet, nor the acronym, that the world has been waiting for.

The premise of the diet is basically a more extreme form of intermittent fasting. With the latter program, you restrict all of your day's eating to one 8-hour window (and yes, sleep time counts as fasting time). With OMAD, however, you are only permitted one meal in each 24-hour period, no snacks allowed. While there doesn't seem to be a time specified for the meal, we're assuming it's game over once you get up from the table, so you'll have to wait another 23-plus hours until you take your next bite. Sounds fun, huh? 

Well, the carrot to the starvation stick is the fact that, on this diet, you are permitted to eat whatever you want during that one meal, no need to count calories or carbs or anything. Which is cool if you hate math, but not so great if you're low on willpower. As one Healthline guest columnist put it, after first trying OMAD, he "realized I had consumed only nachos, wings, and whiskey in 48 hours. This certainly isn't the optimal fuel for a healthy body."

Why nutritionists disapprove of the OMAD diet

Registered dietician Katherine Marengo, LDN, RD, commenting on the Healthline piece, said she does not endorse the OMAD approach as it is "not a diet that can be sustained for a long period of time," and, in fact, presents itself more as "an easy fix to a complicated problem." She even says this diet can be dangerous if followed by kids, young adults, anyone with medical conditions including diabetes, hypoglycemia, obesity, or anyone with a propensity for an eating disorder such as binging.

Another nutritionist, Bonnie Taub-Dix, RDN, spoke with Livestrong about the hazards of OMAD. She said that chances are slim to none you'll manage to pack all of your required daily nutrients into that one meal, particularly if you give in to the urge to load up on indulgent goodies rather than pile your plate with less exciting healthy foods. She also says that "over- and under-consumption of food throughout the course of the day can have negative consequences [including] lightheadedness, erratic blood glucose levels, and irritable moods."

Yet another issue with OMAD is that it trains your body to ignore hunger cues. Ultimately, this leads to you not listening to your body at all, and thus losing valuable cues as to your general state of health and well-being. Also, should you later resume eating three meals a day, you may not be able to tell when you're full, so this could lead to future overeating.

OMAD eating isn't unprecedented

While OMAD might seem like a recent fad, food historian Caroline Yeldham told BBC News, "The Romans believed it was healthier to eat only one meal a day... and eating more than one meal was considered a form of gluttony." She says this type of thinking persisted for many years, and British chef Clarissa Dickson Wright adds the fact that breakfast, now considered by many the most important meal of the day, wasn't really eaten by all social classes until the 17th century.

One modern-day proponent of OMAD eating is retired NFL star turned MMA fighter Herschel Walker. Walker told CNN Health that he never eats breakfast or lunch, and only eats meatless salads and bread for dinner. He's definitely one of those "eat to live" rather than "live to eat" types, though, since he says he sometimes doesn't eat for days at a time, all the while pursuing a grueling seven-hour-a-day training regime. (Don't try this at home, kids!) 

MMA fighter turned WWE star Ronda Rousey also espoused the OMAD diet, telling UFC in 2012 that she ate one paleo meal per day, with her only "cheat" being morning coffee. By 2018, however, Business Insider indicated that Rousey had allowed breakfast, lunch, and snacks back into her life.

There's some upside to OMAD

While many of the health implications for only eating once per day are negative, a 2005 study published in The Journal of Nutritional Biochemistry (via Science Direct) linked intermittent fasting to disease resistance, while a 2017 one published in the World Journal of Diabetes (via NCBI) found that such fasting led to better blood glucose levels. Needless to say, if you're thinking of attempting any type of fasting or another diet to address an underlying medical issue, you should only do so after consulting a doctor.

As far as using OMAD for weight loss, well, yes, any diet that limits your eating may prove to be effective as long as you're able to stick to it. After all, you can probably only ingest a certain number of calories per sitting, and as long as you get full before maxing out your maintenance level, you're likely to lose a few pounds. The problem is that these types of limited eating diets tend to have much higher drop-out rates than do standard calorie-counting ones permitting meal consumption throughout the day, a fact corroborated by this 2017 study written up in the Journal of the American Association of Internal Medicine (via NCBI).

Healthline does mention the fact that OMAD is a good way to improve self-discipline and willpower, but then, so is following any type of diet and exercise regime. You'd do better to pick one with proven health benefits rather than OMAD's somewhat sketchier claims.