Well, in fact, the human body if treated without the context of our modern society, wouldn't be fat. In the animal world, fat animals (for most species) get cleaned up pretty quick, humans no exception. The computer definition you provided is essentially correct, but without an external influence a human body receiving an essential diet would not be fat.

My comment was just joking about percentages, when in fact the person I was responding to (and the following comments) are correct in stating the default is thin, while the average is fat.