We brown bagged a lot in grammar school. I don’t recall teachers or other school officials saying anything to the few overweight kids but they were out there at recess and PE classes with the rest of us.
I call Libs the “New Puritans.” They want to dictate every aspect of everyone’s lives even though their views on sex and perversion are 180-degrees from the original Puritans. The main thing the two have in common is the need for top-down control of the behavior of others. Totalitarianism seems to be built into the Statist impulse.