Yet, all I can ever find is how to eat in order to lose weight. Thus the two issues (health and weight loss) are conflated.
This is the easy problem to diagnose.
The connection between nutrition and health, if obesity is not your concern, seems indeed to be far more nuanced and complex. I'm not sure if anyone has come up with anything better that every expert could agree on except "eat little bit of everything".
I suppose fasting seems to improve biological markers even for non-obese people so it's not only about weight loss as such, though.
I suspect that this is largely due to the fact that industrial food owns the food science in this country, and in most of the developed world. For decades, we were fed (no pun intended) a Food Pyramid that is a blatant lie, because it correlated to how monied interests wanted to feed the nation.
I had my annual physical last week, and my doctor told me that the consensus is now "eat whole, natural, unprocessed foods as much as possible, and probably cut back on meat." That seems reasonable, on its face. It also seems prohibitively expensive for many people.
I'm afraid that there isn't a great solution to this problem in this country, almost by design.