IMO this is one of the biggest and most interesting questions of the last century with the widest and most frightening implications.

If literally a majority of people in wealthy nations are what we define as overweight, and we keep finding new ways that is at least somewhat out of our control or difficult to perfectly control, why do we keep framing it as solely a matter of individual discipline or virtue? I have my own guesses about why of course, but pretty much all of the possibilities are unsettling.