I watched "In Defense of Food" which is based on a book of the same name by Michael Pollan. The main takeaway was: "Eat Foods. Mostly Plants. Not too much." What he meant by that phrase was that it's better for our health to eat less processed and more whole foods, eat mostly plants (less meat), and do not overeat. The most important thing is to be intentional about what we eat and how we eat.
One example that stuck with me was the transition from locally made whole wheat sourdough bread, as has been the case for all of human history up until 100 years ago, to refined white breads with the germ and bran, and thus most of the essential nutrients, removed. Once scientists discovered that the germ and the bran contained the essential micronutrients that people who were getting sick lacked, they added them in to make "enriched" flour, furthering the commercialization of a basic food that did not need any major modification to begin with.