Hi Dyrnwyn, it doesn't sound like true hunger to me, where and how are you feeling the hunger? Is it just a thought that you want to eat, or a feeling in your stomach? Repairs go on during a fast, things that don't usually happen while we are eating, and if something is going on in the stomach or in the area of the stomach it may feel like hunger 'pangs'. One example of this is with our thirst- often our throat lining is replaced while fasting and that can lead to the throat feeling 'raw' as the old lining goes and the new is being 'broken in'. This can leave us feeling distinctly parched and 'thirsty' though it really has nothing to do with our need for water.
I think if you can hold out through these feelings of 'hunger' your body will benefit from the longer fast. However it goes just be careful as always to break your fast correctly.