Swimming at zero degrees centigrade is probably best left to the ducks – who seem not to mind the low temperature at all. It seems like nobody has told this one here that it’s time to migrate. Cold exposure – when only affecting the skin and not allowed to induce hypothermia – has a powerful effect on the hormonal systems within the body. Perhaps the most interesting is the production of the hormone “irisin” which converts white fat into brown fat. Brown fat has the special quality of producing heat from mitochondria without any mechanical action – but there is another hidden value. Brown fat acts as a mitochondrial safety valve – burning off excess ATP (energy molecule) and preventing excessive build up of free radicals associated with genetic mutations and aging. Rats for example don’t have this mitochondrial mechanism and they live for about four years. Pigeons, which have a similar metabolic energy need have a strong mitochondrial safety valve and can live for about 36 years. The hypothalamus in the brain is effectively rewired through cold exposure and this alters the metabolic system considerably as it controls body temperature and the thyroid. So in addition to a ketogenic (high fat) diet cold exposure is a bit like therapy for the thyroid – though a daily drop of 15% Lugol’s solution does wonders too (15% iodine and 30% potassium iodide). Another thing that adaption to the cold brings through the nervous system is a huge reduction in pain sensitivity. All of this of course is very useful as humanity has spent most of its existence in ice. Even today we are in an Ice Age and most people don’t realise it due to political propaganda. Our current Ice Age has been on the go for 2.8 million years. 
