Digestion involves heavy duty mechanical crushing and grinding, at least three sets of enyzymes, dissolving in acid strong enough cut metal, more mechanical squeezing action, and anything microbes can do to the remainder, over the course of several hours.

Up against that, ageing a steak is not going to make a difference. As for bread, if anything, it is easier to digest than something "natural" like raw grains since it has less fibre and anti-nutrients.

The food in question is ever more "processed", since it seems to be made mostly of the base nutritional chemicals.

25% of calories are wasted digesting protein, <5% for everything else.

How is steak processed?

It's worth noting that "processed" is a very loosely-defined term when it comes to food. At it's broadest, even peeling a banana could count as processing.

Check out http://en.wikipedia.org/wiki/Beef_aging

If you're eating aged beef, you're going to know about it, because it's going to be $30/pound... and this is hardly the sort of processing people should be concerned about.

I thought all beef was aged. I have heard the taste is unpalatable at best if it's not aged at all. I'm really curious.

I looked into this a year ago. You're right: "dry-aged beef" is the fancy expensive stuff your yuppie butcher is selling you. "Wet-aged" is everything else -- they pretty much stick it in a plastic bag in a brine that breaks down tissue. If you don't do anything what you have is a curiously tough meat product.

Wet aging is cheaper because you raise the water content (and thus the weight) a little, whereas in dry aging you lose a bunch of moisture, and because it only takes a week or so.