Thursday, September 17, 2015

Cold Adaptation–Thermogenesis

Nobody knows more about thermogenesis than this little character here: Meet Darwin the marmotte! He’s been enjoying a lovely warm summer at 1600m altitude in his own little chunk of paradise – well it is in the area of “Paradiski” –and the views are stunning. From his home here he can see all the views in the subsequent photos.



The water here is at 2.8°C (can rise up to 7.5°C when the sun is out) currently as it comes down directly from the Mont Pourri glacier in a gorgeous waterfall. Gorgeous means “many colours” and here you can see how accurate a description that really is.


Cold adaptation is all about changing metabolism. If you want to control body weight without too much exercise then stop eating carbs and get cold! It’s all about using cold exposure of the skin to signal neural changes in the brain – to switch to “winter” (full hibernation for Darwin) – and so to burn fat instead of storing it! 

Genetic Expression is behind the process – the switching on and off of genes. The hypothalamus in the brain is the master controller for body temperature and it functions on daily (circadian) cycles – unless we switch off the sun (central heating) and get cold! When the hypothalamus responds to cold signals from the skin then this controls hormone production and the subsequent cascade of effects – instead of circadian cycles.


The body adapts very rapidly to cold – taking only the space of a week to eliminate pain and shock. Most significantly part of the adaptation is the generation of “brown fat” which burns white fat as fuel. This brown fat metabolism is achieved without exercise – it generates heat internally without movement  - hence how the marmotte survives the winter asleep beneath the snow – and how we can stay warm at night without central heating and white fat inducing carbs to keep us warm. This is the origin of the term “Cold Thermogenesis” – because the thermogenesis (heat creation) is not through exercise. A new born baby doesn’t have the muscle development to shiver and create heat that way – so it has an abundance of brown fat and will stay warm even if  placed in a refrigerated area (not recommended however!).


We are lucky here as we have pure fresh cold water directly beneath the glaciers – a real gift. Even back home down the valley our water is chemically treated with chlorine gas – producing at least 500 known toxins as by-products.

Despite having been obliged to pay for several offshore survival courses in my lifetime – for North Sea work - not once there did I ever hear about Cold Adaptation or even more disturbingly “Hydrocution”! The point is that they just put you in a survival suit and pretend that this is what survival is all about. It is not! The problem is that when non-cold-adapted people fall into cold water even the contact of the cold with the cartoid nerve in the neck can cause “vagus inhibition” – which basically means that your autonomic nervous system goes into shock and stops your heart dead. That’s the real reason why most people do not survive falling into cold water beyond the first few minutes. The term is “hydrocution” – like “electrocution” but by cold water instead of an electric shock. So, should people working offshore not be taught to be cold adapted? Well the reality is that most of them are obese (or close to it) and will die of heart attacks anyway – so I guess nobody really cares.



No comments:

Post a Comment