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Five Things You Must Know Before Turning Down The Temperature To Lose Weight



IglooYesterday, 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.

@DrSharma
Edmonton, AB

6 Comments

  1. Absolutely right! Many studies like this one seem to look at an elephant through a tiny pipe. The human body is a system and has strong mechanism to pull whatever that diviate from the ‘setting point’.

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  2. Greetings.

    Point by point.

    2. “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.” The study indicates a level of about 15C, but that a range of 18-19C will still work, albeit not as dramatically, and without discomfort (or alternatively, an adaptation). You may be interested in my blog post on this yesterday, where I indicate I’ve set my thermostat for 60F, or about 15.5C.

    3. One of the benefits pointed out of a moderate reduction in ambient temps, or temp cycling, may itself be beneficial in reducing the stress, and they are talking about levels which are not described as being uncomfortable.

    5. This is addressed in their paper, where they state, “One could argue that other changes will compensate for the increased energy expenditure. Indeed, according to
    the adipostat hypothesis, changes in food intake will compensate for alterations in
    energy expenditure and body weight. However, there is evidence that increased food
    intake does not fully compensate for cold-induced NST, and therefore may counteract
    obesity [11].”

    Respectfully,

    Steve

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  3. Exercise, a healthy approach, has been demonstrated in some studies to increase brown fat proportions.

    There is also the risk of hypothermia to be considered when temps are too low, too long. After Superstorm Sandy we were without power for a prolonged time. Now, granted that I already normally run a core temp that is below the average range (though a bit better than it once was) ever since I had a nasty viral bronchitis that is suspected to have inflamed my adrenals with damage left since my thyroid tests stayed normal, but with inside temps that resembled a fridge near the end after Sandy, I got dehydrated while my body temp fell to consistently below 95’F but not as low as 90’F which is a dangerous emergency. Luckily, I did not get bad enough to need hospitalization, but I came way too close for comfort, even getting a bit giddy. Hypothermia is not something to take lightly.

    Certain groups are more vulnerable to hypothermia: the very young, seniors, those with internal temp problems (usually thyroid), and more.

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  4. OK, but what about the influence of ambient temperature on resting metabolic rate ?

    I quote Dr. Criscione : “Whenever the temperature of the environment increases by 1 degree Celcius, (from 22 to 23) our caloric expenditure decreases about by about 2 percent. That’s to say for example, that a daily caloric requirement of 2.000 kcal would decrease by 40 kcal. As a consequence this person will burn about 14.600 kcall less in a year. As every 7.000 kcal in surplus makes you gain 1 kg, you will gain 2 kg per year. “(end of citation)

    Does this mean, that our homeostatic system neutralizes this hypothesis ?

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  5. And besides, the when my place feels cold it just makes me want to bundle up, hibernate, and eat “comfort food”; whereas, I’m more active in more comfortable inside temperatures.

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  6. If having the house cool results in weight loss, I’d be very skinny by now! I keep my heat at 13 at night, 16 when I’m home. Too expensive to heat it much more than that.

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