[Houshalter]

Because that's what the word means? "Nourishing; efficient as food." Obviously what efficient means is different in different contexts. They mean not going hungry or starving to death. We no longer think of that as an issue of course, and tend to worry about other food issues, which is their entire point.

I don't think the McDouble is truly the cheapest per Calorie. Perhaps they man taste/desirability which is more subjective.