It's hardly news anymore that Americans are just too fat. If the endless parade of articles, TV specials and fad diet books weren't proof enough or you missed the ominous warnings from the National Institutes of Health, the Centers for Disease Control and Prevention and the American Heart Association, a quick look around the mall, the beach or the crowd at any baseball game will leave no room for doubt: our individual weight problems have become a national crisis.
Even so, the actual numbers are shocking. Fully two-thirds of U.S. adults are officially overweight, and about half of those have...