It's easy to pack on the pounds in a 9-to-5 world, but not so simple to take them off.
Obesity expert Dr. Jim Levine said that's not surprising: Many Americans sit almost all day long behind a desk. It's that sedentary environment, he says, that's making us fatter and less healthy than ever before.
When "20/20" first met Levine a few years ago, he had outfitted lean and obese people at his Mayo Clinic lab with data-logging underwear to track their every move. What he discovered astonished...Full Story