What are the factors causing higher body weights compared to 60-70 years ago?
I see several...
* high-calorie, high-carb fast-food diets
* massive reduction in use of tobacco (an appetite suppressant and metabolism-affecting stimulant)
* less exercise, less walking, more driving, more sedentary lifestyles
A large transition from predominantly rural America, where almost every one works a hard labor life to a predominantly non-rural America where almost everyone does as little physically as humanly possible.