In the 2008 Pixar movie WALL.E, humans so clogged up the earth with garbage they had to move to spaceships. Motorized chairs ferried the obese blobs portraying people of the future, who sipped liquids from massive cups and sat mesmerized by video screens. It was both funny and scary in its assessment of America’s throw-away, fast-food culture where convenience is everything and self-control and direction outsourced to technology. At the time of the movie it was part of an emerging chorus of voices decrying Americans’ growing girth. Five years later it is almost impossible to go a day without seeing...