It's stunning to me just how many calories moving over land in cold weather takes. Once you cross ~20 miles/day, especially on snow or ice, it becomes practical

It's stunning to me just how many calories moving over land in cold weather takes. Once you cross ~20 miles/day, especially on snow or ice, it becomes practically impossible to maintain your weight. 7000+ kilocalories a day, vaporized into raw thermal and kinetic energy.