I'm loathe to even dive into this discussion as it's so massive and I modify my opinions constantly, but I think a group collaboration should be able to lead us to some good practices. I'll try to touch on a few major points and let the free-for-all ensue.
First, a necessary epidemiological framework for the discussion.
Exclusionary & Inclusionary Principles & Poor Causational Attribution
Reading the literature across different food movements forced me to notice that improvements in health are often achieved through their exclusionary or inclusionary principles rather than the pure philosophical underpinnings of the diet itself.