Hi Joel,
Yes, i'm familiar with Wim Hof. I can't say for certain how he does it or not since i'm not in his body, but he claims it was a combo of practicing learned meditative techniques, as well as some adaptation. Not that he was born with some extra high metabolism.
But what is fairly certain is this, according to mainstream science as is now, he shouldn't be able to survive these feats as a human being. If most people did some of the things he has done, they would die.
Also, his long time meditation practice and certain techniques doesn't just apply to withstanding the cold. In a clinical setting with medical staff, he had himself injected with a non active/dead form of a certain pathogen that even when dead and non active, causes a very strong immune reaction in people…usually.
Wim started to get some slight reaction at first, but he somehow managed to overcome any major symptoms. He essentially said he manipulated his immune system with his mind.
Since i've had a number of anomalous experiences over the years myself, i'm inclined to consider that what he also says is true, we have an inner consciousness which can in the right circumstances supersede or manipulate that area of consciousness we call the "physical". Wim Hof is just one of many people whose experiences and demonstrations suggest that there is much more to us than purely physical. There also have been studies (such as the Princeton, Global Consciousness Project) that have suggested that physical can be influenced by human thought/feelings/consciousness (albeit subtly in this case).

