According to a BBC article from 2016 [0] there were an estimated 641 million overweight people on earth and 462 million underweight people.
I wouldn't call that "very few".
I bet most of those half a billion underweight people are not going to be reading the Washington Post, or even worrying about dietary advice it's from a us-based news outlet.
[0] https://www.bbc.com/news/health-35933691