[Underqualified]

To me eating clean means avoiding preprocessed food, the author is taking a much more extreme view which to me feels like a straw man.

If someone is used to junk food and switches to more fruit, veggies, lean meat and fish, I'm pretty sure they'll start noticing a difference after a little while. I know it worked for me (n=1).

[avenius]

Agreed, I've always considered "clean" to mean non-preprocessed food.

n=2

[pliftkl]

This is the long standing definition, which has been used in the athletic community for much longer than it has in the "wealthy yoga mom" community described in the article.