The first thing to understand about nutritionism is that it is not the same thing as nutrition. As the "-ism" suggests, it is not a scientific subject but an ideology. Ideologies are ways of organizing large swaths of life and experience under a set of shared but unexamined assumptions. This quality makes an ideology particularly hard to see, at least while it's still exerting its hold on your culture. A reigning ideology is a little like the weather--all pervasive and so virtually impossible to escape. Still, we can try.