Canadian here , why is it that at the beginning of winter I can barely be outside without shivering intensely but by the end of winter I can handle it. What is actually happening to my body to create this acclimation?

In: Biology

Over time our bodies are able to adjust to the world around us, it is a fairly slow process taking weeks or months, but as the body detects the changes in environment it changes the hormonal balance in the body, which then changes how our bodies process energy. Your blood “thickens” (it doesn’t actually but the way you circulate blood does change)

I’ve always understood it as the amount of water your body keeps. In summer, you keep more, in winter, less. This aids in bodily heating and cooling.

When you are exposed to cold temperatures, your body starts converting some of your fat tissue into “brown fat.” Brown fat burns fat molecules for heat. Essentially, your baseline metabolism increases and your body is burning more energy just sitting around. Rodents and smaller mammals (including infant humans) tend to have a lot of brown fat to keep themselves warm in the winter. However this is still a newer area of research and not much is definitively known about these processes.

Some more info:

On a side note, I always thought it was interesting how, in the winter, if you set your thermostat to 21C (70F) it can feel cold in the house, yet if it was 21C in the house in the middle of summer you’d love it.