> That's why the seemingly anti-intellectual advice of "eat a variety of foods in moderation" is actually quite good advice.

That is because it is vague, imprecise and can be defined whichever way you want.

For example, how much protein should a person intake? 56 gms per day as per the CDC. Other variant figures in the body building community include like 0.68 gms per kg to 2.5 gms per kg. So which figure does one use to establish the definition of moderation? Genetic and cultural differences also come into play. I have lived in cultures (Africa/Asia) where protein is expensive, eaten less. If I went with that sociological perspective of moderation, I could very easily eat less than the 56 gms of the CDC requirement. If I went with the American concept of protein, which sub population do I go with? Do I go with the traditional American eat a Burger + Mashed Potatoes erry day deal or go all Keto and eat Bacon every day?

Personally, I believe that one should gradually evolve towards a lifestyle that is suited to one's own needs.