could you just put some healthy snacks somewhere and if he's hungry in the morning he can just help himself to them and not bother you? do you have some kind of a clock system that he doesn't come to you unless it's X o'clock? You could do the same thing for this morning snack, though you might want to give an 'earliest possible' time so he's not getting up at 5 for a snack! ie after 6 before 7 you can go and help yourself to a snack without coming to mummy.
I realise this isn't the ideal scenario but it seems that the issue right now isn't to get him to eat but to stop him from bothering you about it. So either you take the route of 'food is at food time if you don't eat then no other snacks, no whining about it either' but I'm not sure how you can stop him whining about it in that case, I'm not sure that you could give a consequence for it at this stage. Or for the sake of stopping him whining you give into the snacking for the time being but do it in a way that he can access it like Bethany said-you'd just have to keep on top of the snack stash.
Sorry if what i've said doesn't make any sense, it's been a long day...
