Papillon you have it spot on.
Just these days, a full packed lunch almost, at break (before lunch) and merienda is HUGE, sandwich, doughnuts, fizzy drink
.
Lunch is exactly as you say, very healthy. A protein with a carb, a salad and fruit/yogurt, plus bread. but DC's get enormous amount of imported fried food now and eat it late (as you say!) 10pm.
Adults eat just as you describe, DC's diets are very different. You notice in the pool, all summer long, thin adults and fat DC's and they eat burgers, crisps, chips and chicken nuggets and fried sandwiches etc.
Their parents have fish and a salad and fruit... absolutely correct on that. Don't know why the DC's don't eat the same as the adults. Mine does!
I live in Valencia though, the 'almurzo' extra mini packed lunch here is particular to here I think, Madrid didn't do this.
School dinners are mega healthy.
The 'old' Spanish diet is amazing. New, not so much.