Earlier quoted context omitted.
Lunch as the primary meal of the day is a staple of Mediterranean cultures. Italy, Spain, Greece, et. al., all have large lunches and small dinners. Latin America is also in many ways a Mediterranean culture so many Latin and Hispanic countries share in that trait.
I don't think this is only applicable to Mediterranean cultures. Eastern Europe seems to follow the same medium/large/small pattern as well.
Here in Berlin that's what it's like as well. We have a big lunch, at least those of us who work in an office.