We were poor. 3 kids, single mom. She made spaghetti at least once a week. That was a large meal and we had leftovers for lunch next day.
We always had a little meat, a veggie and a starch like potatoes. Mom cooked most things from scratch because it went further and cost less.
We didn't eat caned foods very often. She kind of learned how much each of us are and distributed it accordingly and she always ate last. Even when I would try to give ger some of mine, she would say she was full but I wondered.
Fir snacks she would make cookies or buy a bag of candy and distribute it evenly. Everything was measured. Got to be that I could shop and measure so she had some help. You have to sit down with a paper and pen and measure.