Rarely restrict ds food intake and have no rules about what can be eaten/when. Since he was old enough to get to the fridge I have let him help himself. Sometimes he will choose cheese, or I find him knawing on a cucumber, or a stump of white cabbage or a mushroom. Sometimes a yoghurt. Whatever.
The only general rule I have is that he has something 'proper' as his first 'eat' of the day, usually he chooses cereal or porridge, but sometimes it's crackers and cheese or a sandwich. He usually follows this with a cuppa and 2 biscuits of his choice. But if he comes across a biscuit or some chocolate left out by the adults overnight, it's not unheard of for him to scoff that. There are always lots of sweets and biscuits in the house, and although I perhaps allow him to eat more of these than some kids, he can take or leave them too.
Decided on this way of being after suffering a terrible relationship with food and an eating disorder following my mum's issues with what was 'good' to eat or 'bad' etc. We are also relaxed about where and when we eat: no real set mealtimes, we eat when we're hungry, nearly always together in some way, and sometimes round the table, but not always, and I always eat my dinner after he is in bed, as I still like to eat later in the evening (post a glass of wine or two)!!!
Result seems to be, no kind of food is really seen as 'bad' and he has seemed to have developed an instinctive balance for himself, if I give him a plate of selected stuff, cucumber, a cheese sandwich, grapes, sliced apple, celery with peanut butter, a few crisps for example, he tends to eat some or all of everything, not just gobble up the crisps and the bread and then leave the other stuff.
I know it's a bit radical and not to everyone's taste, but I suppose what I'm saying is, being a bit more relaxed about food in general is not a bad thing, and kids don't automatically turn into sugar charged trough monsters if there are fewer rules about stuff...iyswim.