hi! I've been OMADing for just over two weeks now, and while I found it really hard on some days, others have been fine. Not sure why. Every so often I have a bit of a stampy tantrum about not being able to have a milky coffee (I'm not going to have one at 8pm!) and I still dislike the black coffee I drink instead (but mostly I drink tea the way I've always had it, nothing in). I break my fast by cramming cheese into my face while cooking a beautiful meal, so perhaps haven't entirely embraced the spirit of the thing. 
Other than that, it's ok. I've lost 5 lb in 2 weeks and about half an inch off all round, so it's slow but is staying off. There has been a little bit of to-ing and fro-ing with weights this fortnight but the trend is downward! I was on 5:2 for years, on and off, but it stopped working for me as I got older or adapted to it. Now in late 40's, perimenopausal and was despairing of any eating plan that would shift weight and keep it off.
It's not for the faint-hearted though, is it? I have very ingrained coffee shop habits and a black one just doesn't do it for me. Covid sort of helps in that I'm not really comfortable sitting in cafes now (so takeaway instead) but I do miss that. I love cooking and food and couldn't cope with any daily calorie counting (at least 5:2 was just for 2 days a week), and because I taste and nibble while I cook, I'm aiming for 21:3 rather than the hardcore 23:1 - that's ok, right? (sometimes it's more like 20:4...)
Sometimes I have lunch instead of supper, and I've not found the next day (when I wait longer to eat!) that bad.