Here's a vid from a Japanese TV show, showing a restaurant in Japan (I think) claiming to have the World's Largest Hamburger! They start off the vid with a humble 6kg version, but then shortly after 4 guys carry out the big gun.... a 62cm wide, 35cm high "Max Burger"! Made from 30kg of Mince, 180 slices of cheese, 40 tomatoes, 6 onions, 5 heads of lettuce, it comes to 145,100 kcal!!! I'm not sure what the total weight was, or where this burger was made, but it's a damn fine effort! (Anyone that understands Japanese care to translate in the comments?)
Update: Total weight is 60.5kg! (that's 133lb's!!!) That just under
Mallie's 134lb'er, very close to being the world's largest hamburger! (thanks for the comments anon!)
From: http://www.youtube.com/watch?v=5KFSi27IOsQ
The Biggest HAMBURGER in the World!