Approximately 10% of Americans claim to be regular runners. Almost 60 million Americans belong to a gym and about $19 billion dollars a year are spent on gym membership fees. The plethora of fitness centers along with their yoga, aerobics, spinning and CrossFit classes, hiking clubs and sports leagues would suggest that in this country, at least, we're quite fit. Wrong. As a nation, we're fatter and sicker than ever. Why? What happened to all the bikini bods, six pack abs and boundless...