Five Things You Must Know Before Turning Down The Temperature To Lose WeightThursday, January 23, 2014
Yesterday, the media was full of enthusiastic reports that turning down the temperatures in our homes and work places may help fight obesity.
The notion is rather simple – exposure to cold would force us to burn more calories (thanks to our brown fat) to stay warm, which in turn would help us lose weight.
If only things were that simple!
So before you run off to turn down your thermostat, here is what you need to know about brown fat and energy balance:
1) We all have some brown fat (on average younger individuals and men have more than older individuals and women) and even small amounts of brown fat do help burn calories, especially when we are exposed to cold (non-shivering thermogenesis).
2) Exposure to cold does indeed increase the amount of brown fat – but experiments where this has been done involve exposure to rather cold temperatures for several hours a day. Not much is to be expected from simply turning down the thermostat a couple of degrees – we are talking COLD exposure. (incidentally, you would lose any extra brown fat as soon as you stop exposing yourself to the cold – so this is by no means a permanent solution)
3) One of the main mechanisms through which cold-exposure increases brown fat is by stimulating the sympathetic nervous system, therby releasing large amounts of stress hormones (like adrenalin and noradrenaline). In fact, earlier in my career, we used cold exposure in my laboratory as a “stress test” to examine blood pressure and heart rate responses in volunteers – it is fair to say that this test was not a very popular with our volunteers.
4) An increase in stress hormones can not only increase heart rate and blood pressure (a classic scenario for precipitating heart attacks in people with coronary artery disease) but could well (at least theoretically) promote the development of insulin resistance and fat accumulation (is anyone wondering why mammals that live in the cold protect themselves with thick layers of blubber?)
5) Even if a few ounces of extra fat tissue did help you burn more calories, thanks to our homeostatic system, this will probably simply result in an increase in appetite – a couple of bites is all it takes to eat those calories back.
So while my Dutch colleagues may be fascinated by the idea that turning down our ambient temperatures may help us burn a few calories – I am not holding my breath to this “solution” to the obesity epidemic.
Also, given that the vast majority of people with excess weight actually live in places where the only option to experience “colder temperatures” would be through more air-conditioning – this is not even a proposal that would make any environmental sense.
But of course the media loves this story – how can they not?
Remember, anything that sounds too good to be true, probably is.