What the hell is "clean eating", anyway?

[Arch0wl]

A subset of the bodybuilding community (and even the underground bodybuilding community friendly to performance enhancing drugs) is obsessed with "eating clean."

Truly, I have no idea what this is because I've heard so many differing opinions.

Some people say it's avoiding processed foods, but this seems ridiculous since that wouldn't necessarily change the nutrients in the food, and it's unclear how this would radically alter your muscle development at all.

Purely in terms of macronutrients I *guess* this could mean some kind of fat/carb ratio, but again, everyone has some different take on this, and it seems like one of the more new-agey concepts bodybuilders like to talk about.

In terms of subsets of micronutrients, I could see arguments for reducing sugar or sodium, but that's for blood sugar and blood pressure levels respectively. Trans fats are obvious to avoid, too. But beyond this, I'm really not sure what "clean" could mean, since not only is this vague ("clean" is someone's perception of a certain nutrient balance, we don't actually know what that nutrient balance is) but it varies from person to person.

Is there some kind of established science to what a "clean" bulk would look like, or is this just broscience?