Part of the problem in America is the obsession with portion size, rather than food quality and natural ingredients in the average diner/run-of-the-mill restaurant. It seemed that it was pretty standard to get enough food to take a second meal home in a box, which I can only imagine gets munched back at at the ranch with a bottle of coke and a bag of Doritos.
When I used to ask people if a particular restaurant was good, they invariably would rate a restaurant on portion size, which is a bit odd to a European.