MAD stands for one meal a day and is an increasingly popular diet where an individual only eats one meal per day. The OMAD diet is the most aggressive form of intermittent fasting, where an individual will eat one large meal during a one-hour window and then fast for the next twenty-three hours. More common forms of intermittent fasting allow an individual to have a five to eight-hour eating period during the day and then fast for the remainder of the day.
Proponents of the OMAD diet purport it supports fat loss, but as of now, no peer-reviewed studies support this. The basic premise of a diet is to restrict calories, and the OMAD diet follows calorie restriction in the same way that all intermittent fasting diets do, with eating periods. Intermittent fasting works for individuals because they are only eating during a certain period of the day, so they eat fewer calories during that period versus when they were eating at any time of the day.
Proponents of the OMAD diet also like it because they can eat whatever they want during their one meal. While that is true, two issues arise with eating whatever you want, and those are the two of the main problems with the OMAD diet.
Two of the main issues with the OMAD diet are meeting your nutritional goals and volume. Yes, it is possible to have your one meal for the day be anything you want, such as mozzarella sticks, a burger, fries and a milkshake. While that sounds like a great meal, it lacks the proper micronutrients an individual needs for sustenance daily. Further, eating these types of meals on a daily basis could lead to nutritional deficiencies.
The next issue is the total volume of food required in eating one meal a day. The total number of calories an individual needs per day depends on a variety of factors, but according to the United States Department of Health, the average caloric intake for adult women ranges from 1,600 to 2,400 calories per day for adult women and 2,000 to 3,000 calories per day for adult men. Consuming that many calories in one meal could be challenging for individuals not accustomed to eating that much food in one sitting.
As with all diets, the best diet for you is the one you enjoy and will be able to follow. In conclusion, in the absence of peer-reviewed evidence, the OMAD diet likely is not a good choice because it is not sustainable due to the amount of food that must be consumed during a one hour period.