Sure, what once took additional walking in the supermarket (from the frozen pizza section to the cookie section of the dairy case) now takes less. Convenience.
Americans need less exercise and more calories... or so the votes they cast with their wallets would indicate.
Actually, I think you've got this all wrong.
Americans know they're all fat and disgusting... but this is their new diet plan. Buy shitty pizza and gross cookies in a single package so to eat them together such that they induce vomiting. If you've ever watched Ally McBeal, you'll know that computer-animated babies are fucking creepy, and that vomiting is a great way to attain a skinny figure.
Vomit your hearts out, you freedom-loving motherfuckers. Vomit yourselves to such beautiful figures that the rest of the world will forever envy you.