Sounds like a walk in the park for an ascetic. We forget how comfortable we’ve become, 250 years ago this would have been your average Tuesday.
"The researchers collected data during the unique ceremony in Tibet, where nuns were able to raise their core body temperature and dry up wet sheets wrapped around their bodies in the cold Himalayan weather (-25 degree Celsius) while meditating. Using electroencephalography (EEG) recordings and temperature measures, the team observed increases in core body temperature up to 38.3 degree Celsius..."
https://www.sciencedaily.com/releases/2013/04/130408084858.h...
If it’s scientific then it must be well understood in terms of cause and effect. In which case, it is like any other physical phenomenon, nothing special.
And if it’s not scientific, rather if it’s a mystery, then scientists will have to take a call on what is.
It was more about questioning the relevance (and authenticity) of "deep mysteries" and "existence" etc. It was not about whether or not human beings can train themselves to endure such difficulties. Which they can, apparently.
When you said "it would be a cake walk for an ascetic" I thought that by ascetic you meant one who is into meditation and all such "deep realities". Not Wim Hof.
Nevertherless, I personally don't see any virtue in being hungry in -1 degree celsius, if I have food and a warm home. Except in case someone is making money out of it, like Wim.