Believing something with 4000 years of tradition in different cultures, was validated in several studies is "religious".

Versus believing something that came out last year, and has only single study sponsored by manufacturer...

I'd say you're misinterpreting what belief implies here Tradition isn't proof, but also it doesn't harm credibility, at least to coherent people, and that's how it should be*

Eventually if there's enough proof, the consensus shifts, regardless of how much initially people try to deny it

Fasting goes against recent consensus, yet it's becoming both more researched and more recommended (At the very least at the layman level, I'm no dietician)

* Something working doesn't tell you why it works, so it's important to be rigorous and always check, else you risk cargo-culting unnecesary or even risky things

...and rational people when combined with justification and evidence.