For an overnight fast, we are only just basically letting our digestive system finish digesting what we have eaten that day, and then go a few hours without food. There have been days when I was too busy to eat all day, and only ended up with one meal for that reason, and not because I was doing OMAD. I think we have all had iMessage when we missed a meal, and didn’t feel the need to work into our food slowly.
If a person is fasting for a week or more, or even for several days, then it might help to ease back into food with something like soup or a smoothie; but I can’t think that it makes any difference after a simple overnight fast.