• The One Meal A Day (OMAD) diet is a form of intermittent fasting where you fast for 23 hours and eat for the same 1-hour window each day.
  • It's recommended you consume your, one, meal after your most active part of the day.
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The One Meal A Day (OMAD) diet is an extreme version of time-restricted eating, like intermittent fasting. However, unlike intermittent fasting which usually allows a four or eight-hour eating window, the OMAD diet has a one-hour eating window. So you fast for the other 23 hours of the day.

Although various forms of intermittent fasting have been shown to be an effective way to shed pounds, the OMAD diet is not recommended by nutritionists and can even be dangerous for people with certain health problems. Here's what you need to know.

What to eat on the OMAD diet


"Generally speaking, if only eating one time per day, one should consume the amount of calories required to meet their daily energy needs in that meal," says Kelsey Hampton, CSSD, a registered dietician and certified specialist in sports dietetics.

"Most adults should not consume under 1200 calories per day," she says. It sounds obvious, but getting enough calories is extremely important as too little may compromise the immune system and breakdown muscle mass as the body resorts to other ways to maintain energy reserves, says Hampton.

It's important to maintain proper hydration when on the OMAD diet. The diet allows water, coffee, or tea consumption throughout the day, but no other beverages, like low-calorie or diet beverages, are allowed. It's also recommended that you eat your meal at the same time every day to ensure a consistent 23-hour fasting period.



Morning meal:

Evening meal:

  • 309 Calories: 1 cup of lentil soup (169 calories) with 1 cup of roasted Brussel sprouts with parmesan (140 calories)

These examples merely reflect popular breakfast and dinner options but you can vary the foods as you see fit. Just remember, while it may be tempting to eat whatever you want on the OMAD diet, it's recommended that you focus on nutrient-rich foods that ensure you're getting enough vitamins and minerals.

The science behind the OMAD diet



"When you eat once a day, you feel weak and sick. When it comes time to eat, one tends to overeat which can lead to a surge of insulin and ultimately feeling unwell," says Melissa Rifkin, a registered dietitian and owner of Melissa Rifkin Nutrition in New York City.

Who should not try the OMAD diet


As for a healthy adult, "it may be safe, but that doesn't mean it is ideal," says Hampton.


"There are healthier ways for people to eat while reaching their goals. Lean protein, plenty of produce and quality fats and carbs can provide a broad spectrum of nutrients and can be tailored in a way to meet many different health and wellness goals," says Hampton.

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