I don't consider food to be something we spend leftover money on. Food (groceries) is a budget item. As is petrol.
Lunches are all taken from home (DH can't buy lunch). So that's included in groceries. General spending money is only for eating out, gifts, days out, and other random things.
I think if you lump too much into 'general spending' then you don't really know what it goes on, and where you could save if needed.