The main benefit of OMAD is that you’re not repeatedly telling your body to keep storing fat, which is obviously incredibly helpful if you’re having trouble with weight management or need to lose weight.
Every time you eat, you’re telling your body to produce insulin, which is the main hormone responsible for storing fat. If you only eat one meal a day, that means your body only gets the signal that one time, meaning that you’re going to be burning up stored energy for the rest of your fasting window.
I feel that OMAD isn’t all that risky, but some people do run the risk of becoming malnourished if they maintain a poor diet for longer periods of time. It’s important to make sure you’re getting a proper amount of micro and macro nutrients when eating just once a day, as well as supplementing your diet with a multivitamin.