The cool down work out

The new campaign by Sports England This Girl Can encourages women of all ages in England to get exercising, explaining rather eloquently the simple science of how to lose weight: to get “sweating like a pig”.


Getting active, hot and sweaty is the usual way we’d expect to make a difference to our winter-pudding waistlines. But while fanning myself with a copy of the Daily Express after an intensive Bikram Yoga session recently, I caught a glimpse of an article explaining that I could instead simply cool my home to boost my calorie burn.


As quoted in a Daily Express article on 11 January 2015, author and sports scientist Ms Peta Bee claims that:

“...if the average adult spent a few hours a day sitting, working or walking in a cooler environment, we could all burn a third more calories each day. Just turning your central heating down can boost calorie burn by six per cent and make a difference to your waistline.”


Ms Bee makes these claims in her recent book, The Ice Diet, in which she also insists that having her family live in cooler temperatures has made them healthier, her son getting sick less often than his classmates.


Saving on heating bills and not actually having to step one foot out the door to lose weight was, undeniably, a rather enticing prospect. But I decided I’d ask Ms Bee for the evidence supporting her claim.


In response, Ms Bee sent me two published articles: a 2011 study by Johnson et al. in Obesity Reviews and a 2013 study by van der Lans et al. in the Journal of Clinical Investigation.


From a cursory glance, the two articles do suggest that lower temperatures require more energy expenditure and hence a higher calorie burn, supporting Bee’s claim. However, a slightly more detailed look reveals a few limitations in the evidence. The first study pointed out that previous research hasn't looked at the effects in humans, while the second study had a sample size of only 17 people, all of them in their 20s. The study itself concluded “...more prolonged studies are warranted”.


As a result, I am more cautious about claims of calories evaporating in our air conditioners or open windows. Whilst there’s nothing wrong with trying different diets and lifestyle options, it’s crucial to be able to spot which ones are underpinned by evidence or are simple marketing fads. As the Ask For Evidence campaign on Spoof Diets by the Voice of Young Science network highlighted:


“...the decent [diets] are drowning in reams of conflicting advice, dodgy nutrition claims and self-styled gurus in newspapers, lifestyle magazines and all over your Facebook feed... we need to make more of a fuss about all the silly stuff because it isn’t without consequence – people actually introduce malnutrition through overly restricted diets, they buy expensive products and exotic foods, and they lose heart following unsustainable diets when they need to make a significant health change.”


For now, then, it looks like I’m going to stick with Sports England’s advice and get exercising.


Image by Nathanael Coyne (CC-BY-NC-SA 2.0)


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