If a person is doing intermittent fasting but still eating each day for one meal, as we do in OMAD, there really is not any problem with being concerned about what we can eat. I have read that when a person is doing a cleanse, or longer fast, then it is important to start out with drinking broth, or something that is easy for the stomach to digest, and slowly come back to full meals.
I am eating one meal each day, so I basically just try to choose foods that are healthy and provide good nutrition for my body, and then eat just what would be a normal amount of food.
I started the intermittent fasting by first eating a low carb/Keto Diet, and that stopped the food cravings, and then I just began cutting down on my daily meals until I am now having the one meal each day.