I'm using the word "fanatic" becuse I think it's meaning is the closest to what I am trying to describe: "a person marked or motivated by an extreme, unreasoning enthusiasm, as for a cause." It isn't intended as an insult or perjorative, but a descriptor.

I am coming from the perspective of being genuinely interested and wanting to try such a diet but unable to find any good information in the sea of fanatical marketing.