There is an extreme type of interval fasting that is becoming more and more trendy – but experts strongly advise against it
The OMAD (One Meal A Day) diet is a form of interval fasting in which you fast for 23 hours and then eat in the same one-hour window each day.
It is recommended to eat the one meal after the most active time of the day.
Children, the elderly and people with health problems such as diabetes should not try the OMAD diet.
This article was medically reviewed by Samantha Cassetty, MS, RD, nutrition and wellness expert with a private practice in New York City.
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The OMAD diet (One Meal A Day) is an extreme form of intermittent fasting (also called interval fasting). Unlike the normal form, which allows eating during a four to eight hour window during the day, on an OMAD diet you are only allowed to eat during one hour of the day – so the remaining 23 hours of the day you are fasting.
Although various forms of intermittent fasting have been shown to be effective for losing weight, the OMAD diet is not recommended by nutritionists. For people with certain health problems, it can even be dangerous. Below we have gathered everything you need to know.
What you can eat on the OMAD diet
The OMAD diet does not restrict the type of food you can eat or the number of calories you can consume in this one-hour eating period. However, you should be careful to consume approximately the recommended amount of calories for your height, weight, age, and gender.
"If you only eat once a day, you should generally consume the amount of calories needed to meet your daily energy needs with that meal," says Kelsey Hampton, nutritionist and certified sports diet specialist.
"Most adults should eat no less than 1.200 calories a day to eat," she says. It may sound trivial, but eating enough calories is extremely important: Too little caloric intake can compromise the immune system and lead to the loss of muscle mass as the body tries to meet its energy needs in other ways, Hampton explains.
It is important to drink enough while on the OMAD diet. The diet allows water, coffee or tea consumption throughout the day – but no other drinks are allowed, no matter how low in calories they may be. It is also recommended that you eat your meal at the same time each day to ensure a consistent 23-hour fasting period.
"It’s best to consume this meal after the most active time of the day. This helps your body recover from exercise and replace nutrients it burned during activity," Hampton explains.
To give you an idea of what a meal might look like on the OMAD diet, here are two examples of a morning meal and an evening meal. Please note that these are only meant to illustrate what a healthy meal can look like – and are not recommendations.
680 calories: One cup of oatmeal (307 calories) prepared with one cup of two percent fat milk (120 calories), topped with one cup of fresh sliced strawberries (53 calories), one-quarter cup walnuts (200 calories).
685 calories: Omelet with three eggs (240 calories), a quarter cup of shredded cheddar cheese (220 calories), a cup of spinach (7 calories) with an avocado (218 calories).
467 calories: One cup of green beans (50 calories) with 30 grams of sliced almonds (172 calories) and one large baked sweet potato with butter (245 calories).
Total calories: 1.832. However, depending on your age, weight, gender and activity level, you may need more or fewer calories.
880 calories: 300 grams of boneless, skinless chicken breast (429 calories) with one cup of quinoa (150 calories) and two cups of broccoli (61 calories) sauteed with two tablespoons of olive oil (240 calories).
350 calories: Kale Salad with Pumpkin, Edamame and Apple Slices
309 calories: One cup of lentil soup (169 calories) with one cup of roasted Brussels sprouts with Parmesan (140 calories).
275 calories: One medium banana (105 calories) with a quarter cup of almonds (170 calories).
Total calories: 1.814. However, depending on your age, weight, gender and activity level, you may need to eat more or less calories.
These examples simply represent popular breakfast and dinner options, but you can of course vary the foods as you see fit. Just remember that while it may be tempting to eat whatever you want thanks to the OMAD diet, it’s highly recommended to focus on nutrient-dense foods to ensure you’re consuming enough vitamins and minerals.
The idea behind OMAD
Less extreme versions of intermittent fasting that allow a four- or eight-hour eating window have been shown to improve glucose tolerance, increase insulin sensitivity and aid in weight loss. However, eating an unusually large meal can have the opposite effect.
A 2015 study in the journal Nutrition Reviews warns against extreme versions like the OMAD diet because it can lead to abnormal increases in appetite and body fat percentage.
"If you eat only once a day, you will feel weak and ill. When it’s time to eat, you tend to overeat, which in turn can cause your insulin levels to spike and eventually make you feel unwell," explains Melissa Rifkin, a certified dietitian and owner of Melissa Rifkin Nutrition in New York City.
Who should absolutely avoid the OMAD diet
Rifkin warns that the OMAD diet can be dangerous for children, the elderly and people with health problems such as diabetes. These groups need a steady supply of calories. People who regularly take prescription medications should also refrain from the OMAD diet, as most medications should not be taken on an empty stomach.
For a healthy adult, the OMAD diet "may not be harmful to health, but that doesn’t mean it’s ideal," Hampton says.
Both experts, Hampton and Rifkin, agree that there is not enough research on which to base a recommendation of this diet as an appropriate method for weight loss.
"There are healthier ways to feed yourself and achieve your goals at the same time. One with plenty of lean protein, many different products and high-quality fats and carbohydrates can provide a wide range of nutrients and can be tailored to meet many of one’s health and weight loss goals, Hampton says.
This article was translated from English by Tristan Fiedler. Find the original here.