My retired parents moved to Cocoa Beach for 3 months. The did not bring a car, so I bought them bycycles. I would come over on weekends to visit and they would take my car to go serious shopping.
But, during the week, one or both of them would go to the grocery store and pick up supplies. They could only buy an amount of food and such, that would fit in the basket of the bycycle.
My Dad likes to tell the following story:
When he was younger and did not have a lot of money he would buy food based on the price.
When he was older and an officer in the Air Force, he learned about calories and he bought food based on calories.
Then it changed. Fat became the thing to watch, so he bought food based on low fat.
Then he got to the bycicle phase so he bought food based on size.
Since then, he has a car at home and he has learned that wheat (gluten) is bad.
Oh and dairy is dubious.
What to eat?