Around 1968 we went from understanding that frequent snacking, and consuming starchy and sweet foods makes you fat to whatever the new lay undertanding of calories was. The prevalent memes were, "a calorie is a calorie", "calories in = calories out", and "eat less move more", and probably also "eat smaller meals more frequently".
And in the early 1980s, we villified fat, further adding carbohydrates to the recipe.
