Anecdotal - the only thing that worked for me was eating once per day, around 6PM. I was very alert the whole day, but not in an unpleasant way. The hunger pangs come and go, but are manageable. Tried this for a week, I don't drink coffee at all but this felt like I've had a couple of cups.

A nutritionist friend however dissuaded me to go this route, as apparently it is very hard for our bodies to process that amount of food and one will end up with various nutrient deficiencies in the long run. I'm curious to know if someone got intermittent fasting to work long term though.