I make my coffee from very dark/espresso beans, but run some additional water through, so it comes out like heavy-duty coffee but not true espresso. And I use the equivalent of 4 "shots" worth, all in one big 16-oz cup. That's my one "cup" of coffee for the day, but it's a serious cup. LOL
Confess, Dayglored! You clicked on this article because at the very least, it offers an aspect of entertainment. Clickbait is by definition not even entertaining.
Therefore, even if the study was observational and imprecisely defined, it’s not quite worthless! :-)