[jnbiche]

> but the graphs I can find show that there is a steep increase in the late 70's, not after the Dietary Guidelines were written in the early 80's.

But still, the upward trend follows the cultural meme that "fat is bad" that started propagating in the early 1970s. The dietary guidelines only formalized that bit of "scientific wisdom".

(naturally, correlation does not equal causation, but it does often indicate a phenomenon of interest, worthy of further investigation)

[scholia]

You are correct....

The McGovern committee (of the U.S. senate) published the first Dietary Goals For The United States in 1977. This was supposed to reverse the epidemic of heart disease.

McGovern rubber-stamped the prevailing views first made popular by Ancel Keys' Seven Countries Study, published in 1970. https://en.wikipedia.org/wiki/Seven_Countries_Study

So the steep increase in starting in the late 70s is right on time....

[CuriouslyC]

Perhaps people thought science had "solved" how people get fat (eating fat) and ate more assuming if they avoided fat, they wouldn't get fat. "I can eat an entire box of snackwells and there's only 5 grams of fat!"