I followed the 1986 Will Steger https://en.wikipedia.org/wiki/Will_Steger expedition to the North Pole quite closely at the time. I recall they spent a lot of time developing and preparing foods for the journey, in particular a high-fat pemmican. They also ate huge amounts of butter -- as much as they could stand.

It is interesting that in Otzi's time the necessity for a high fat diet in extreme cold conditions was understood -- or perhaps that is just how they came to live.