The first time I fasted (last Thursday) I had 3 small meals for my 500 calories, and was not just hungry, but also cranky and had a headache. Not massively hungry, not massively cranky, and not a big headache, but enough to make me a bit blah. So next fast day (Monday just gone) I didn't eat until dinner. I found it so much easier. Hunger passed in waves, I drank loads of water and green tea, and never felt low on energy or any hint of a headache. I did feel pretty hungry after a small dinner, and I'm sure it was the eating that set it off.
So today I"m aiming for that again - loads of liquid, ignoring any waves on hunger and just getting on with the day, then a small dinner.