I like the use of the term “kernel” because I think it gets back to keeping it simple.
Like you, as a physician, I don't know much about nutrition. I think that there's more and more awareness of talking about calories, about carbohydrates and about particular components. People gloss over this, and really we're talking about whole foods—purchasing and cooking whole foods at home. That's the basis of food literacy.
We know more and more that the strongest link with ill health is consumption of ultra-processed foods, so we need to get to the Brazilian style of the whole plate. The new Canada food guide is also a good model for a healthy plate. I think we have to simplify things to some extent and focus on whole foods, foods that your grandmother or great-grandmother would recognize as a food, food that's not ultra-processed.
Cooking and eating at home together is strongly associated with good dietary habits. Those are foundational things like staying away from added simple sugars. You can have your simple sugars once or twice a week, but not every day.
You don't really want to demonize foods, but, on the other hand, what some of the dieticians call common sense around foods isn't that common. There are a lot of parents who don't cook food and their children don't know how to cook food, so we need to get back to some basics and simplify things.