Just for those of you who like statistics; keep in mind that this is Wikipedia and may not be entirely accurate, though it looks to be close to other statistics I've seen (that I'm too lazy to find).
http://en.wikipedia.org/wiki/Obesity_in_the_United_States
EDIT: And it looks like this data is a bit old now, but is probably good enough for a general idea.
EDIT 2: http://www.medicalnewstoday.com/articles/193321.php
Here's a more recent one, and the one that I was trying to find in the first place.








