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 / Updated  / Source: TODAY
By A. Pawlowski

With so much interest in intermittent fasting, here comes buzz about a more extreme version of the eating plan: the OMAD diet.

Over the weekend, Twitter co-founder Jack Dorsey confirmed he's part of the movement, fasting most of the day and eating only dinner.

What is the OMAD diet?

OMAD, the acronym for “one meal a day,” is sometimes also called the 23:1 regimen because a person spends up to 23 hours a day fasting and only eats during a brief window. A much less strict version of the approach — the 16:8 plan, which requires fasting for 16 hours and allows people to eat whatever they want the rest of the day — has many fans among researchers and dieters.

But experts are much more wary about OMAD. Kristin Kirkpatrick, lead dietitian and manager of Wellness Nutrition Services at the Cleveland Clinic Wellness Institute in Cleveland, Ohio, has a few patients who’ve been following the plan for years. But for most people, life getting in the way and old habits can make sustaining the diet very challenging, she said.

“While I am a fan of fasting, this approach is not something I would advise in most scenarios,” Kirkpatrick told TODAY.

“Someone with prior eating disorders could spiral back in with this approach; it carries too high of a risk of malnutrition, and the ability to stay on it long term is difficult.”

Still, OMAD in one form or another is a regimen people have been following even before the diet had a buzzy name. Todd Becker, who runs the “Getting Stronger” blog about thriving on stress, told TODAY in 2015 that he usually ate dinner, but often skipped breakfast and lunch.

Venture capitalist Vinod Khosla recently told The New York Times he fasts until dinner because “food slows him down.” There's a section of Reddit devoted to OMAD, where people post photos of their meals and exchange tips.

What does a typical day on the diet look like?

The main rule is to eat only one meal a day. That means no snacks, little nibbles or "grazing" every few hours, but you can drink calorie-free beverages such as water, and black coffee or tea at any time.

Beyond that, variations exist, but Jennifer Oikarinen, a registered dietitian at Banner - University Medical Center Phoenix in Arizona, told Women’s Health that people often follow these rules:

  • Pick a four-hour sector of the day, say noon to 4 p.m. or 2 to 6 p.m., and always eat within one hour of that time to stay consistent from day to day.
  • Use one dinner-size plate, about 11 inches in diameter, for your meal.
  • To avoid having piles of food, the meal shouldn’t be higher than 3 inches.

What should you include in your one meal to stay healthy?

“You would have to be smart about your meal choices,” Kirkpatrick said.

No foods are excluded, but to avoid malnutrition, she advised including fruits, vegetables, whole grains, healthy fats and adequate protein at each one-time meal. You’d have to aim for at least 800 calories to get all the macronutrients you need, such as carbohydrates, fats and proteins, but it would still be “next to impossible” to get all micronutrients, like vitamins and minerals, she noted.

The goal should also not be based solely on calories since a big fast food meal could contain well above 1,000 calories, but would lack nutrient density.

A typical OMAD meal would likely have to have larger-than-average portions and more fat to boost calories. Meals should also vary from day to day to ensure nutrient variety, Kirkpatrick noted. She suggested this sample meal (which doesn’t follow the one-plate rule):

  • Large salad with olive oil-based dressing
  • Grilled salmon or chicken with whole grain such as farro or quinoa with mixed beans or lentils
  • Fruit salad for dessert

Kirkpatrick also advised taking a daily multivitamin and fish oil supplement.

Would a typical person doing this lose weight?

Yes, weight loss is all but guaranteed because this is considered a very low-calorie diet, Kirkpatrick said.

Would a person be starving?

Starvation is the presence of malnutrition, where the body begins to seek fuel from muscle because it has no other options, Kirkpatrick noted. If calories and nutrients are severely depleted, the body can definitely start breaking down muscle, she added.

“If the meal is large enough, however, it can supply fuel for the time in between meals. This is why the structure of the meal is so important,” Kirkpatrick said.

What are the major concerns with this diet?

They include malnutrition, mood swings, hypoglycemia (low blood sugar) and muscle wasting. People who are underweight or have a history of eating disorders; pregnant or breastfeeding women; people prone to gall stones or those who have type 1 or 2 diabetes should stay away from the OMAD plan, Kirkpatrick warned.

What are the potential benefits?

Weight loss, especially for people who are carrying an extreme amount of extra weight, Kirkpatrick said.

“Someone who is morbidly obese, not on medications and has a strong motivation to try this diet may do well, but my assumption is that this would not be a long-term approach,” she noted.

Again, Kirkpatrick would not advise OMAD for most people, but if you want to try it, be sure to work with a doctor or dietitian familiar with the diet to make sure you are doing it right.

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