Known as the Standard American Diet (though Wikipedia calls it the Western pattern diet), it is "generally characterized by high intakes of pre-packaged foods, refined grains, red and processed meat, high-sugar drinks, candy and sweets, fried foods, high-fat dairy products (such as butter), eggs, potato products, and corn products (including high-fructose corn syrup). Conversely, there are generally low intakes of fruits, vegetables, whole grains, fish, nuts, and seeds."
It's generally agreed-upon to be unhealthy, but how to move away from it is a much harder question. Capitalism, food deserts, willpower, etc etc all get talked about. But regardless of whether or not it's a good thing, how SAD is your diet?
Photo taken from https://upload.wikimedia.org/wikipedia/commons/d/df/Walmart_Wenatchee.jpg
Growing up, my diet was almost 100% SAD, with one exception: even poor kids in America generally get fruit. Fruit was available, even if it was just apples/oranges/bananas most of the time.
Almost everything was packaged or made with packaged products (casseroles--the great mid-late-century family filler!). A good home-cooked meal was a meat, bread (or other carb such as pasta or possibly potatoes), and a canned vegetable. This was largely not the fault of my parents; neither of them were taught to cook and both were young and poor. My mother and her siblings weren't even allowed in the kitchen and their generation still had few men who knew how to feed themselves. Of course, that neither of them ever learned to cook is much more on them.
Fortunately for me, I had a natural love of food and curiosity for all things foreign, so I taughtmyself to cook when I was an adolescent. Once I was able to drive, I took over all the grocery shopping.
These days, my diet is maybe 30% SAD. Worse than it used to be because I can no longer cook as much as I used to (disability/health issues) and rely on instant food or delivery more than I would like. I also enjoy the occasional junk food, of course. Mostly, I live on seafood, produce, and simple carbs (white rice or noodles).