Fallows has a series of really interesting posts up on obesity and class. This one contains an anecdote which I don't doubt for a minute:

"I had a friend from my paramedic job come visit me in the city a couple months back and bring his brother and a few of his brother's friends, who all work physically demanding construction jobs.  The construction guys, who are all stocky but in various stages of growing beer guts, somehow got into a fight with this group of guys who were built like lumberjacks.  It was a draw.  I later found out that the lumberjack guys were all "Big 4" accountants - CPAs who somehow had better arms and fitness levels than those who actually used their bodies for a living."

I've done my share of time at bars here in New York, and I'm clear on this--You don't really want it with them Wall Street niggers. Part of the problem is sheer power of being young, paid and having an Equinox membership. But the other part is that they are the other side of straight hood. Project niggers think they have nothing lose. Wall Street niggers think they aren't capable of losing. Either way, it's a problem.

I'm telling you, if I gotta mix it up with some of them fools, I'm breaking beer bottles, gouging eyes, kicking shins, and kneeing groins. It won't be gangsta. But it will leave a mark.