Show me evidence that replacing unsaturated fat with saturated fat improves human health outcomes.

You'll find that this "debate" cashes out into two sides: one side points to the balance of scientific literature on human health outcomes, and the other side hand-waves over mechanistic speculation.

For example, the latter side likes to blame seed oils when they actually improve human health outcomes: https://www.the-nutrivore.com/post/a-comprehensive-rebuttal-...