What is the theme or central idea of The Hunger Games?

There are a number of themes in the book that could be
argued as the main or central theme, but the constant theme of an individual working to
overcome a corrupt system is one that stands out in my mind.  Katniss constantly has to
find ways to improve and strengthen herself in order to fight back against those who are
running the games and ultimately the leaders responsible for the system in the first
place.

Another possible theme is of course as simple as
good versus evil, the innocent and hard-working people in the different districts having
to fight against the decadent and lavishly living capital is another theme that comes up
again and again.