From Cynthia Lair's Feeding the Whole Family"Can I imagine it growing?. . .tough to picture a field of marshmallows. . . A whole food has only one ingredient - itself. . .Is this product 'part' of a food or the 'whole' entity?"
My take on this:
Whole Food not: juice
Why? a fruit that has had its skin and pulped removed.
Whole Food yes: apple
Why? Grows right on the tree - I've gone apple picking and I have to say that an apple picked right off the tree is INCREDIBLE
I've kept this simple, but of course there are degrees of whole, like Clarity said.