I went to an Eclipse book signing last night and couldn't ask this question...?

It makes sense for them to die without drinking blood, just like humans will eventually die without eating/drinking. but if it's so hard for them to control themselves around humans when they're so thirsty wouldn't they just rip somebody's throat right there? it's their instinct... like Edward with Bella that first day... if you haven't already, read (on Stephanie Meyers's website) the first chapter of Midnight Sun, which is the book Twilight from Edward's point of view. it's amazing.

Yes, technically a vampire who didn't get nutrition would wither away and die - turn to dust. Vampires have to feed in order to survive just like all creatures. Have you read Bram Stoker's Dracula? You really should. He really sets up a clear set of guidelines under which vampires must live. Since you're done Eclipse and have time to kill (no pun intended) read the original. Pax - C

i believe that the vampire would have the same reactions as humans without food

They would die a very painful death. They would also...

1.Become scary and have a huge bloodthirst.

2.Become super weak.

vampires rule