FOOD PYRAMID!! That's when the whole high carb/low fat thing started.
Took about 10 years to start seeing damage and since then has skyrocketed.

People smoke much more back then too. Do you think people ate less beef and more fish, chicken, and duck? I remember my relatives said they caught catfish, when duck hunting, and raised chickens right in the city. Everyone I know that was an adult in the sixties and seventies seemed to have gardens even in the smaller cities. Any little plot of land was put to good use, at least by my relatives.