I dunno, when I think back, we got up later, had 4 dedicated meals and went to bed earlier. From what I remember of my childhood (vaguely), getting up before 8 am was unusual, breakfast was large (porridge with milk or butter or quark with home made jam or eggs and tea), school started at 8:30-8:45, lunch was at 1 pm from 3 courses (soup, main and dessert drink), then mid-afternoon we ate at ~ 4 either sour cream or sweet fruit drink with something or cheese, and finally dinner was main and tea with something (normally bread and jam). We did not have fruit for much of the year, so preserves were the big thing. I went to bed by 8:30 pm and there was hell to pay for any bathroom trip after that. Adult's working hours were 10 am to 6 pm, iirc, with lunch from 1 to 2 pm.but in the past children were taught not to eat, nor ask for food, between meals, so they would eat more of the food they were given, and also so they'd learn the two different states of hunger, and satiety.
Now, my child has to be up at 6:30 am to make the before-school care at 7 am, and she does not go to bed till 8:30-9 pm. So her day is 2 hrs longer than mine. I normally pack a meat item, a vegetable container, 1 fruit and 1 'something else', a larabar or another fruit or an egg. She also eats breakfast and supper. So, that's probably 5 meals. She is fine going for 4-6 hrs, sometimes more without food.