[petertodd]

I'm convinced that cold stress adds brown fat and/or regular fat cells to your body from personal experience: when I started caving about a decade ago I had way worse cold tolerance than I do now; as caves are formed by water most caving is a relatively wet and cold activity. My cold tolerance also got rapidly better, maybe in about two or three years worth of caving, without much weight change associated with it, so I'd guess it was mainly putting on brown fat with maybe some redistribution of the existing fat I had.

Of course, that's no magic bullet: I've probably put on something like 20lb in that timeframe. I definitely need to get more exercise and eat better.

[hd4]

I've been taking cold showers since 2015 and have noticed a huge difference in my cold tolerance and also in how my body reacts to the food I've eaten. There is a point (around winter unsurprisingly) where it becomes too stressful because the water gets too cold to shower in. Anecdotal but I noticed I did lose more weight when I was taking regular cold showers, plus it helped me take up more exercise as my body became a bit more resilient and enduring.

[drjasonharrison]

cold tolerance is also influenced by the ability of the muscles to burn fat to create heat. Adaptation to colder environments takes about two weeks. Ray Cronise's blog discusses this also.

[petertodd]

Ah, interesting! Does that "two weeks" of exposure mean two weeks total of cold exposure? Two weeks after cold exposure? Or something in between?

I'm only a moderate caver, so the longest I've been exposed to cold in that context is something like 16hrs straight, or maybe 32hrs total in a 3-4 day period; most of my exposure caving is much less than that, more like a few hours at a time spaced apart by at least a week.