For the first time, today's children may not live as long as their parents. If you want to know why, look no further than their elastic waistbands: America is fat, and getting fatter. But according to my next guest, for some people - some adults, at least - being overweight is a perfectly reasonable decision. Eric Finkelstein is a health economist and author of the new book, The Fattening of America: How the Economy Makes Us Fat, If It Matters, and What to Do About It.