The only way for you to adjust is to get out there
I live in Northern Canada (i'm one of the most northern members on VT)
it goes from +37c in the summer to -40c in the winter.
Now -40 is cold no matter how you look at it
But once I adjust to winter temp's i'm good in -20c
-5c and i'm running around in a T-shirt perfectly warm.
When I was in Victoria this summer it was really warm the whole time and then one day it dropped to +24c and I was cold
You adjust by being in it
Theres nothing that you can eat that will change that