I think this is where I really fall down. Mainly because I ALWAYS want to eat. There's not a time where I want to say no to food.
Because of this I try to judge my hunger by the clock. If I had a substantial breakfast at 8:30am, am I really hungry at 10:30am or am I just letting my mind take over? Basically, I set myself targets that I will next eat at Xo'clock and not before.
Maybe one day I'll be able to go by what my head tells me, but it's not going to be for a very long time.