Thinner is richer ?

       [ Fact of the matter is that "middle class" is a moving target and people who used to be middle class aren't expending the effort to keep up. They aren't "slipping away" so much as they're "slipping behind".]

Shades of Ayn Rand here in NPR land ? So if you are not solidly middle class, you have nobody to blame but yourself ?

By the way, from a scientific perspective human effort - mental and physical - is measured in CALORIES. The ruling class tends to be more attractively thinner than the working class, but that does not explain their being more obnoxiously richer. I refer you to Marx's Das Kapital.