Yes.
50s/60s/70s and even 80s kids ate fast food too - if anything, girls in particular were less concerned about “healthy” eating, but since portions were smaller, people weighed less overall.
Yes, but we didn’t eat it as often in the 50s,60s,70s, & 80s. These days, even a dinner prepared at home is largely “fast food”. Have you noticed all those fully prepared meals in the deli section of your grocery stores? They are generally high fat, high sodium. And they take no effort to slip into the microwave to heat. At least when our mothers and grandmothers prepared a meal, it took a little bit of real cooking.