I recommended this Wuesthof kitchen knife to a friend of mine whose wife is in her early 50s.......and turns out doesn't do much cooking, sewing, etc.  (it's a great knife and even made in- get this- Germany for 50 bucks)
He replied that their daughter is a bit of a throwback and is the only decent cook in the house.

That got me thinking.  Back in the 1950s and early 1960s, we had a "June Cleaver" conception of what a married woman should be.  "Nice girls" didn't have sex before marriage (or weren't supposed to) and there was real dating and courtship.  Once married, wives were supposed to be subservient to their husbands, got in the kitchen, made him a sammich, poured him a drink when he got home, cooked at home, etc.  I don't recall my parents talking about dining out much during that era.  Like in Norway today, restaurants were an expensive luxury then.

Fast forward a few years to the complete cultural chaos of the late 1960s.  Jane Fonda, Gloria Steinem, et al were defining what women should be.  Women had to have a career to be a proper woman.  As household incomes rose, they started dropping their kids in day care, and were too busy to cook quality homemade meals.  They turned to chain restaurants and fast food, turning out cheap, processed food (that would soon be prepared by illegal immigrants) and American consumers demanded more food for less money.  As an example of companies trying to maintain their profit margins by cutting costs, Coke and Pepsi started using high fructose corn syrup in the early 80s, and obesity tracks closely with HFCS usage.  

As competition among "casual dining" restaurants in a growing market increased, restaurants owners had to turn to cheap labor to prepare the food, wash dishes, etc.  Rocked by chaos and civil war of the early 1980s in Central America, a tide of unskilled, uneducated workers began flowing into the United States legally and illegally.  White and black Americans soon found themselves "above" that kind of work.  The increases in minimum wage only accelerated the illegal immigration.

Furthermore, back in pre-Women's Lib era, women were expected to stay trim and be attractive.  Once they started burning bras, they declared that they could look however they wanted.  Divorce skyrocketed and an increasing number of children were being raised in single-parent households (mainly divorced mothers).  As women grew bigger, being overweight became socially acceptable.  

Cliff Notes version: women's lib caused obesity and accelerated illegal immigration.

What says GD?

All I can say is that culture and society and the rules / mores that direct its path are all inter-connected.  Every action or reaction has repercussions.

That may be true.  So what would you say caused the dramatic rise in obesity?