Yes they were. They were doing highly physical work on limited calories.
In the fifties you burned a lot of calories just living. And while calories were not as limited as they were before and during WWII they were not as easily accessed as they are today.
Now things that took energy to do can be done with the push of a button if even that is needed.
Let's just look at what it took to pay the phone bill. You went to the bank, stood in line, took out the money, went to the phone company, stood in line, paid your bill.
Today the money is taken out of your account without you lifting a finger.
In the fifties you burned off at least a hundred calories paying the phone bill. Today, zero.
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.
I’m almost 80 and never stood in line to pay a bill...checks and a 3 cent stamp did it all! Even in the early 1950’s!