I've found success doing OMAD, often with a 48-hour fast once a week. (Once, I went 5 days.)
Anyway, what works for me with OMAD is eating one meal until I'm full. I don't count calories; I just limit my carbs and eat natural, unprocessed, "real" food. Plenty of dietary fat and plenty of veggies, and some fruit. This keeps me healthy and at my maintenance weight.
It's also how I lost my 40 pounds in 2-1/2 months, and reversed my type 2 diabetes in less time than that. I'm happy with it. I've been maintaining since Easter of this year.
RE: Fasting Journal : I'm probably not doing OMAD correctly.