What Cold Actually Does to Your Blood Sugar

A ten-day study raised insulin sensitivity by 43 percent. Then a second study found nothing, and the difference between them is the interesting part.

Welcome to the Journal. This is a free article. New pieces go out free to subscribers first, and land in your inbox the day they publish. After that they move into the members’ archive, so your inbox is the place to read them free. Subscribe below and you will not miss one.

Members get the deep dives as well: the protocols, the doses, the exact how.

Cold exposure is sold as many things it is not. But there is one metabolic effect where the science is genuinely interesting, often misunderstood, and worth taking seriously: what cold does to your blood sugar and your insulin sensitivity.

I want to walk you through the real evidence, including a result that looks spectacular and a second result that complicates it, because the gap between them tells you more than either does alone.