Every claim on FitChef synthesizes evidence from multiple independent studies. Some claims are backed by large meta-analyses where every research group found the same thing. Others rest on smaller studies with mixed results. These are fundamentally different levels of evidence — and readers deserve to see the difference at a glance.
That's what certainty tiers do. They describe how consistently the evidence points in one direction. Not whether FitChef thinks the claim is "true." Not whether you should act on it. Just how aligned the research is.