I've never tried it, but you could say that my family used to somehow do it -- we often ate breakfast foods for dinner because it was cheaper. Of course, we also ate breakfast foods at breakfast, so it wasn't very balanced. Hum.
The old saying is probably to tell us to eat a lot in the morning, to jump-start the day (these calories will be burnt by moving throughout the day), and not too much for dinner, because we won't be needing much energy during the night (plus eating heavy meals before getting to sleep can prevent some people from sleeping well). At least, that's the way I've always understood it.