I may be a bit older than you're looking for (44, grew up in small town Indiana) but it just so happens I was back in the US for Thanksgiving and happened to discuss nutrition education with other members of my family. All of the nutrition education I remember was structured in terms of the four main food groups: meat, dairy, grain, fruit & vegetables - focusing on the idea that these should all be represented in a balanced meal. We also were taught about nutritional content, mainly which vitamins are represented in which food groups (and which specific foods), but almost entirely separately from "meal planning". This was hardly changed from the nutrition education my parents received some 20 years previously.... although not surprising as a few of the teachers were the same! My younger siblings (38, 40) saw the introduction of the fifth food group, fats & sugars as I recall, presented as bad things that should be avoided. Also the presentation of the four food groups was somewhat altered, bringing nutritional balance (and the "recommended daily allowance") a bit more to the forefront in meal design. (All of the above is based on our memories of nutrition education which may be highly flawed!)

Does he argue there was a change of opinion in the 80s or before that? If I recall correctly, he argues that the guidelines have remained roughly the same for decades, or even changed for worse.