"The average American leaves 53 pounds, or $329 worth, of food on the plate at restaurants every year...."

"Changes to that number over time are hard to track.... But anecdotal evidence suggests such a change in diners’ perception of leftovers.... 'There are some people who have a thing against them.... 'People who just say, "I don’t eat leftovers," as a matter of principle.' But for others, she said, leftovers are a question of logistics. How much food is left? How many boxes are needed to take it home? How much time do I have to eat it? What am I doing after I leave?... Members of Generation Z grew up with the ability to order whatever they want, whenever they want, from their phones. Why bring home food from one restaurant when you can easily order something fresh the next day?... 'I think maybe it’s embarrassing, like you don’t want to be the equivalent of going to an all-you-can-eat buffet and putting rolls in your dinner jacket'...."

From "Is the Doggy Bag Dead? Restaurateurs in big cities have noticed a somewhat surprising shift in diner behavior" (NYT).

The article doesn't mention it, but the term "doggy bag" originates in the presumed embarrassment of taking home leftovers. It's for the dog, not for me.

The OED traces the "doggy" euphemism to a 1952 issue of American Restaurant: "It's a pleasure to hand this beautiful Doggie Pak to your patrons To Take Home Bones For Their Dog... Printed in three colors... It's class."

Then there's this line from "The Cat Who Ate Danish Modern" (1967): "'Doggie hungry. You take doggie bag,' said the caterer, and he pushed a foil-wrapped package into Qwilleran's hand." I was completely unfamiliar with the "Cat Who" series, but it looks like a big deal in the world of mysteries and prompts me to observe that nobody leaves a restaurant with a "cat bag." But then, nobody says "Who let the dog out of the bag?"