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Eating One Big Meal A Day: The Key to Weight Loss and Better Health or Just Hype?

The OMAD diet sounds a bit mad, but experts say the perks are real.
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Fast Facts

  •  OMAD is a form of intermittent fasting where your calories are limited to a single meal.
  • Eating one meal a day has been linked to weight loss, lower inflammation, improved mood, and more. 
  • OMAD isn’t for everyone; talk to your doctor before adoption it (or any new diet).

Most of us have spent our lives eating three square meals a day. In fact we’re almost hardwired to hit the panic button if we miss lunch. But eating three meals a day is just one of many options on the “menu” of meal cadence, say experts. And proponents of the OMAD—one meal a day—diet suggest that paring down your eating time to just an hour a day may help accelerate weight loss, lower inflammation, and reduce the risk for various diseases. All of which may help you live longer.

But is limiting your calories to a single feeding time really healthy—and doable—for the average man? Here’s everything you need to know about the OMAD diet to help you decide if it’s right for you.

What is the OMAD diet?

The OMAD diet is a highly restrictive form of intermittent fasting (IF). Where some styles of IF have you fasting half the day or 18 out of 24 hours, the OMAD diet pushes the envelope to the furthest extreme and limits eating to a single hour out of 24.

Why would anyone want to restrict eating to a single hour each day? Weight loss (1) is the biggest driver here followed by the potential for a few other pretty remarkable benefits like sharpened memory and focus (2), lowered inflammation (3) and longevity (4). All the same potential benefits of any fasting plan, only on steroids.

While there is very little research on the OMAD diet or intermittent fasting to date, says nephrologist Jason Fung, M.D., an expert on intermittent fasting and low-carb diets and author of The Obesity Code. But the research so far suggests that OMAD may offer potential health benefits.

Related: Lose Weight and Boost Nutrition With The Keto Diet

Intermittent Fasting

There are a handful of forms of IF, based on your eating and fasting windows. What they all have in common—and what sets them apart from other diet plans—is that with intermittent fasting you focus on when, not what to eat.

Intermittent fasting can give your body a prolonged break from breaking down and digesting food, a process that requires significant energy and resources.

There are multiple types of IF, including:

  • Time-restricted eating (x hours off: x hours on)
  • Alternate-day fasting (fast one day, eat regularly the next)
  • The Warrior Diet (one big meal a day along with small fruit and vegetable snacks)
  • Eat Stop Eat (abstain from food for up to two days in a week)
  • 5:2 (eat normally for 5 days followed by two days restricted to 500 calories)
  • One meal a day (OMAD)
 

So why choose OMAD? “The idea is simply to give more time in the fasting state,” says Fung.

Related: The Easy Guide to 18:6 Intermittent Fasting

Just like 18:6 is more advanced than a 16:8 or a 14:10 fast, “OMAD is more powerful than 18:6,” he says. “If you only eat once a day, you are likely to eat less overall, since it is hard to eat so much food at a single time.”

  • Studies have linked OMAD to weight loss, improved memory and focus, lower inflammation, and longevity.
  • OMAD is a form of intermittent fasting with a long fasting state and short eating window. That can make it hard to overeat.

The Benefits Of OMAD

Research on forms of IF like OMAD show that giving your body a break from digestion may have many intriguing perks. Among the most exciting:

Weight loss

Successful weight loss is the result of being in a calorie deficit, and when you’re only eating once a day, that becomes easier than ever.

“OMAD is more powerful than 18:6, and it is often easier to keep to this schedule,” says Fung. “If you allow six hours to eat [instead of one], you generally will eat more.”

One study involving normal-weight, middle-aged men compared the OMAD diet to a typical three-meal-a-day diet. Researchers found that the OMAD eaters saw significant changes in body composition including a reduction in body fat (5). An increase in hunger, blood pressure, and cholesterol were also noted.

Lower inflammation

Too much inflammation in the body has been associated with diseases and conditions such as cancer, Alzheimer’s disease, diabetes, and heart disease (6). Abstaining temporarily from food may help reduce inflammation.

Here’s why: According to a study led by researchers from Mount Sinai, when subjects fasted for a short period of time, the release of pro-inflammatory cells called “monocytes” into their bloodstream were reduced. During periods of fasting, these inflammatory cells went into sleep mode and were less inflammatory than monocytes found in those who were fed (7).

Brain benefits

Improved learning, memory, mood (8) and mental focus are some of the potential benefits suggested by studies so far. Research suggests that intermittent fasting is a promising, innovative strategy that may help prevent and treat mental health disorders such as depression, as well as sleep disturbances, and cognitive impairment (9).

One study examining fasting and weight loss revealed that people who practiced IF for eight weeks experienced notable improvements in their emotional well-being and depression compared to the control group (10).

Longevity

What other potential benefits than weight loss, a sharper brain and less inflammation for better disease protection can you hope to get out of the OMAD diet? How about a longer life?

A few studies are investigating the potential for fasting to play a role in longevity. One process those researchers are exploring is that fasting may have the potential to help us live longer thanks to a process called “autophagy,” a fancy word that basically means a process by which our bodies clean house, getting rid of damaged cells to make way for new, healthier ones (11).

A broad review of animal studies published in The New England Journal of Medicine suggests that calorie restriction through intermittent fasting may help promote longevity (12). More research needs to be done to see if this benefit extends to humans, too.

OMAD’s hormonal impact

With all the potential health benefits the OMAD diet may offer, you may wonder what the hormonal implications of eating just one meal a day might be. Fung says they are mostly positive. “The main hormonal impacts are those of the metabolic hormones: decreased insulin, increased growth hormone, and sympathetic tone (increased concentration and energy).”

  • By giving your body an extended break from digestion, the OMAD diet may boost weight loss, lower inflammation, improve your mood and help you live longer. 

Just because you can eat a couple of Big Macs and supersized fries on OMAD doesn’t mean you should.

What Do You Eat on OMAD?

One of the most celebrated facts of the OMAD diet are how easy and simple the diet is. After all, you only have to plan, shop, cook, and clean up after a single meal a day.

While some OMAD proponents say that you can eat anything you want for your one meal a day, nutrition and weight loss expert Jonny Bowden, Ph.D., CNS, cautions against sitting down to a meal of your favorite greasy or fatty dish.

“Just because you can eat a couple of Big Macs and supersized fries on OMAD doesn’t mean you should,” says the author of more than a dozen books and creator of Meta-Fasting.com.

“Poor food choices create all the conditions we’re trying to eliminate,” says Bowden. “It contributes to insulin resistance, inflammation, massive amounts of unnecessary calories, which will make it harder to lose weight—as well, highly-processed foods often contain chemicals, sprays and toxins, which can add to oxidative stress. When the bloodstream is flooded with these chemicals and toxins, continuing with a poor diet makes it all the more difficult to cleanse or detox the body.”

Beyond sticking to common sense and nutrient-dense, whole foods, Bowden says there are no “rules” per se. You don’t count calories and everything you plan to eat for your one meal a day should fit on a single plate. Resist the urge to refill your plate, buffet-style.

According to Bowden, OMAD aficionados also say your plate shouldn’t be higher than three inches.

Possible Risks And Considerations

As with any kind of fasting, there are certain people that should steer clear of OMAD.

People with diabetes, anyone who has suffered from an eating disorder, and anyone on blood pressure or heart health medication should avoid fasting without speaking with their health practitioner.

If you struggle with gaining weight or being underweight, often feel hungry or have issues sleeping, you may also want to avoid time-restricted eating. And always check with your doctor before starting any type of fasting regimen.

Bowden notes that doing OMAD every day can also leave you with a protein deficit. He suggests most people eat between 80 and 120 grams a day. “That’s a lot of protein for one meal.”

Related: 10 Protein Myths Busted By Real Science

But you don’t have to worry about that if you’re only doing OMAD a couple times a week, he says. “You don’t have to do OMAD every day, and probably shouldn’t. Varying your schedule when you fast is considered a good idea.” One way to do that is to alternate between one meal a day and two meals a day.

Another downside: It can be hard to pack all of the necessary nutrients into one meal. “Most surveys show over 70 percent of Americans don’t get the optimal amount of magnesium, and studies of vitamin D levels show a huge number of people aren’t getting enough of that either,” he says. 

That’s why—whether you’re eating one meal a day or multiple—Bowden recommends the following supplements for everyone: fish oil, magnesium, vitamin D (with K2) and a multiple with both zinc and selenium.

Related: The Top Supplements for Muscle Building

The Bottom Line

Eating just one meal a day (OMAD) has been associated with weight loss. Studies also suggest OMAD may help improve insulin resistance, increase cognitive function, and decrease inflammation. However OMAD isn’t right for everyone, and it can be hard to get the recommended amount of nutrients from a single meal. If you are considering OMAD, talk to your doctor first. intermittent fasting can be intense, so start with a less-intense form of IF, and work your way up.

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