[systemsweird]

Also the body will increase metabolic rate in the cold to maintain body temperate which is an externality they aren’t measuring. The user of the worse clothing is very likely burning more calories and still not as warm. This would mean increased fatigue and greater food weight on expeditions.

[throwaway173738]

Or they can move faster or carry more weight. You can warm yourself by moving or by metabolism.

[IAmBroom]

"We aren't carrying the best gear, so we'll just hurry a bit climbing Everest... and carry heavier packs of food, too."

[tantalor]

It's mostly from metabolism, friction is negligible (<1%).