In any cold snap, all anyone really wants to do is wrap up in a duvet and hibernate until the sun shines harder. Probably the last thing on your mind is to turn down the heating, open a window and forgo the thermals. But what if it helped you lose weight? In the hottest field of science, findings have shown how embracing the cold can accelerate fat loss and boost the body’s metabolic rate. In 2015 Californian researchers suggested that exposure to colder temperatures is key to lasting weight loss, in a study that showed getting outside in winter, turning down the heating and opening a window can blast away fat. As a new study reveals that turning the thermostat down could even improve the condition of those with Type 2 diabetes , the argument for shivering our way to good health is ever growing.
Even compared to our grandparents, we have become a coddled generation. We live and work in warm environments. One third of people bask in homes heated up to 25C and one in 20 lounge in an almost tropical 30C. We work out in warm gyms, shop and eat in the centrally heated indoors. We wear duck-down jackets on mild autumnal days and drive around in heated cars when it’s too cold to walk. Our inner temperature gauge is rarely challenged and, when it is, we just crank up the thermostat. We’ve entered what some scientists have called a state of ‘thermal monotony’ and our bodies’ calorie burning tally, primed to respond positively to changes in temperature, has nosedived as a result.
A downside, of course, is that none of us want to be shivering. Even with the promise of a leaner and lighter body, trembling with cold is too miserable a prospect for anyone to endure on a regular basis. So, here’s the good news: we don’t have to live in a human fridge to lose weight. Exposing ourselves to less extreme temperatures can also burn calories by the bucket-load.
In pre-shiver mode, when you feel cool but not freezing, your body prepares to keep you warm by producing heat internally. What’s more, cool temperatures fire up the body’s stores of brown fat, a good fat that, unlike the blobby white stuff that settles on our thighs and stomach, actually sends calorie burning into overdrive.
How much difference can it make? Published scientific studies show that consistent chilly living (that’s several hours a day in a cool room) can see a 30 per cent rise in the amount of calories we burn. But turning down the central heating by just a couple of degrees to a comfortable 18-19C has been shown to boost calorie-burning by at least 6 per cent. In one trial at the US National Institutes of Health (NIH), groups of healthy men and women who were asked to lie still in a cool room wearing light clothing for half an hour at a time, burned as many calories doing that as they would on an hour-long cycle.
Of course, diet matters too. In The Ice Diet (Penguin, £7.99), I recommend a 14:10 approach which advocates eating 2-3 meals a day (no snacks) within a ten hour window. That way your body is allowed a 14 hour mini-fast, shown to prompt good fat activity even further. Acclimatise to a cooler way of living and the pounds will melt away. Ray Cronise, a former NASA scientist who has since published several scientific papers with Harvard researchers on the health benefits of cooling strategies found men can burn an extra 2,800 calories a week and women 2,100 calories - the energy equivalent of running a marathon every seven days. It’s a no-brainer. And the hottest thing you’ll do all year.
The Ice Rules
1) Turn down the thermostat: Resist turning on the heating in autumn until it’s absolutely necessary. And when you do, keep it lower than usual. About 19-20C is as high as your heating needs to go. Get used to it by adjusting in increments.
2) Open a window: Airtight double glazing creates a warm, stifling environment that is of absolutely no use to our bodies when it comes to fat-burning. Even if you do it for once an hour in the winter, let the cooler air in.
3) Sleep in a cooler room: Reduce the tog of your duvet if needed and open a window. A bedroom cooled to a perfectly reasonable 19C has been found to stimulate good brown fat and trigger the body to burn more calories into daylight hours.
4) Take a cooler shower: This sounds hardcore, but in reality a cold blast at the end of the shower will suffice. Try a 5 minute warm (not scorching) shower followed by 10-20 second blasts of cool water to get used to the lower temperature.
5) Switch temperatures: Our good fat responds best to changes in indoor temperature without ever letting rooms get too hot. We can easily tolerate changes of 2C per hour, so alternate the temperature in your room from around 16C to 19C every 60 minutes.
6) Get outside: There is no better place to get good brown fat doing what it is good at than the great outdoors. Make a concerted effort to spend at least the equivalent of 5-10 minutes for every one of your waking hours outdoors. For most people that is around 1-2 hours a day.
7) Watch what you wear: Protect your extremities in very cold weather, but don’t layer up beyond your needs. Prioritise ear-muffs or a hat, gloves and socks rather than woolly jumpers and fleecy layers.
8) Live according to the seasons: A simple rule of thumb I like to stick to is never to walk around the house in a t-shirt when the heating is on. If you do, it is too hot. Way too warm in fact. Get back in touch with the fact that it is winter, it is meant to be colder and you are supposed to throw on a jumper or cardigan to keep warm. Humans were not designed to be oven-ready.