For those with good blood sugars, a cold shower causes your liver to release glucose into your bloodstream, and your white fat cells to release lipids, in preparation for thermogenesis. So your brown fat cells are burning everything they can get: glucose, lipids, ketones, to maintain body temperature. Those in ketosis prior to cold exposure could very well see a temporary drop in ketone levels because the liver will replenish blood sugars faster than it will replenish blood ketone levels.
Ice bath affects on ketosis test for fun
Fangs
#22
and ice bath for fun! One poster said it it all----CAN NOT COMPUTE!
old thread but too funny and wow on that experiment, takes guts and glory I donāt have 
polarbear2101
#23
Ahh I see. Thanks for the insight and if I have anything else to add through noticing something out of the ordinary from my personal experiments, Iāll be sure to share them with the community.
amwassil
(Michael - When reality fails to meet expectations, the problem is not reality.)
#24
Like pretty much everything I suspect thereās at least some genetic predisposition as well. Those of us with the āpredispositionā burn everything available to keep the temp up via thermogenesis. My experience is that I will get hungry before feeling cold. When I start to feel cold itās because I didnāt eat soon enough to refuel. I suspect those without the āpredispositionā tend to add insulation rather than āturn up the heatā.
tpseager
(Thomas P Seager, PhD)
#25
I donāt have the science on the genetic predisposition, but what youāre saying makes sense to me. My ancient ancestors are from the North Sea in Europe, and I live in Phoenix AZ. Iāve become convinced that I need cold exposure to maintain metabolic health because (for whatever reason), Iām not built for the desert climate.