Until there is sufficient (if not equal) food for all, I consider this planet grossly overpopulated. While I understand even in old times, someone (probably a dumbass lost in the woods, and evolutionarily deserving to die as something other than "the strongest) would starve to death -- but bottom line is, when entire nations are starving there's a problem. Space is not an indication of vacancy -- Adding a city block worth of space to an over-crowded restaurant may bring it within fire code, but it won't increase the potential patronage without first accommodating many other needs -- kitchen, staff, consumables and tables not withstanding.
"Earth" and "Population" are much more than a ratio of earth mass to man mass. There are great cultural and economic considerations that must be considered, as population is only as stable as the bodies that represent it. While the majority of the earth's patrons may not be starving, I can assure you --with great confidence-- that continuing to increase the population will in no way alleviate the problem(s). Is the earth so short of space we couldn't possibly fit another body on it? No. We could cram billions more onto the surface of the earth easily -- and even more if we wanted to start burrowing. Is there evidence to suggest there is more life on this planet than can be supported without extreme social and economic changes throughout the world? Undeniably yes.
Don't mistake me for benevolent, though -- I'm not personally concerned -- I'm admittedly a misanthrope. I'd pretty much keep calling it over-populated until I could count the population on my fingers. Fortunately, evidence supports my claim at the time.
On the upside, I'm sure we'll destroy ourselves well before we find out just how many we can cram in this phone booth.