Check out this video from the 60’s or was it the 70’s. I’m not sure.
https://www.youtube.com/watch?v=qglBm-N-Lnw
Where could you go today to find that many thin teens in one room. Certainly not to Walmart.
Compare the calories burned playing an hour of pinball with the calories burned playing an hour of Call of Duty.
People used to burn a lot more calories.
They used to eat a lot less calories.
QED, people used to be thinner.