I've started OMAD on the 8th of May 2024, and till the 8th of August 2024, so that's 3 months, I've lost 10 KG (weight is, let's say, below 100 KG before I started)
If I had to guess, I think I've been eating around 400 to 800 calories a day.
The first half of that time I'd usually walk 15-30 minutes a day, but stopped in the second half (environmental reasons), and would walk half an hour to an hour if I broke my OMAD (because of an outing with friends for example).
Right now I'm testing for a month or two (after that last above date) on just calorie intake, where I'd eat whenever I want but keep the calorie intake to similar levels as before, and see how that goes.
If I'll see similar results (basically around 3 KG a month loss) then one does not necessarily need to do OMAD or intermittent fasting, but literally just to be mindful of what you eat.
However, from what I looked into, there are other health benefits to OMAD and IF, so even if the test goes well, I'd still have those methods in mind in my general for my general eating life style.