I think the cope is actually believing that some magic thing made people more lazy between now and the 80s.
You’re right we didn’t evolve since the 80s. But our food has certainly changed. It’s not like some God from above put laziness in peoples brains just now. No… people were always lazy.
It’s just that you could be accidentally skinny before. You can’t be accidentally skinny now, it has to be intentional.