Back in the late 70s and early 80s my brother started a landscaping company. I worked for him in the summers when I was in college. We got the contract on every McDonald's in Kansas City and I lived on quarter pounder's fries and chocolate shakes. Of course at that age resilience to bad food is as good as it will ever be, and the hard work we were doing was healthy, but I still had terrible acne, and other indications that I was eating food that was not good for me at all. I remember one time we were doing a big lawn renovation project on some very nice home, and my brother said "what do you want for lunch I'll grab you something" I said "just get me one of their biggest burgers" he went to a little local joint and came back with a burger that had five hamburger patties on it, fries, chocolate shake . . . the bottom of the bag was so saturated in grease it was translucent. In those days I could eat anything including that, but I do recall that it sat in my stomach like a rock. It's a miracle I survived.Indeed.
I'm trying to remember the last time I ate at a MacDonalds. Some time in the 1990s.
White bread is another killer. Cheap and ubiquitous. Its the filler that the poor use to ease pangs of hunger. Leading to an obese population that is deeply malnourished.