Ok, finished my first week. Tuesday was awful and I was a bad tempered so-and-so. Friday was easier, although I did wake up hungry in the middle of the night.
Tips that helped me stay off the grub on fast days:

Go outside and do something/anything. Get out of the house.

This sounds a bit pathetic, but I have bought a computer game. I was so absorbed in it I forgot about being hungry. (Game was Company of Heroes)

Get an early night.

Keep repeating “TOMORROW IS ANOTHER DAY”. Once you get to about 6pm you’ll have cracked it!

Good luck!

Thanks Stef. Yes, Water is the key isn’t it. Apparently the brain struggles to differentiate between Hunger and Thirst.