If there’s a single benefit to being cold, it’s that it can help you burn more calories. Here’s why you should turn down the thermostat, from FastExercise.
More than 30 years ago I watched a science documentary about something called “brown fat.” Unlike normal fat, brown fat contains a lot more mitochondria, which is what makes it brown. Brown fat is most commonly found in newborn babies and in hibernating mammals. It is there, primarily, to generate heat. Unlike the more familiar yellowish-white body fat that stores excess calories, brown fat does the opposite. It burns calories. When “switched on,” brown fat produces around 300 times more heat than any other organ in the body.
Back in the 1980s it was thought that activating brown fat would be one way to solve the obesity problem. But things didn’t work out so well. Though it had been known for some time that babies have deposits of brown fat around their shoulder blades to help them maintain their body temperature (babies are not very good at shivering), scientists couldn’t find brown fat in adults. So they decided brown fat must disappear in infancy once it is no longer really needed. Interest in brown fat dwindled. Recently, thanks to better technology, it has returned.
In the last decade, researchers carrying out PET-CT scans have found traces of brown fat in adults, particularly on the upper back, the side of the neck, in the dip between the collarbone and the shoulder, and along the spine. Not a lot, but enough to encourage further investigation.
It turns out women have proportionately more brown fat than men and it is more readily detectable in lean people than in the obese, although researchers are still not sure why. What’s now accepted is that brown fat persists into adulthood and that there are a couple of ways of activating it. What we don’t yet know is how big or significant this effect is likely to be.
High-intensity exercise certainly leads to a flood of hormones like noradrenaline, known to activate brown fat. Exposure to cold will also encourage your brown fat to burn through a few more calories. Using thermal-imaging techniques, researchers at the University of Nottingham’s Queen’s Medical Centre have shown that plunging your hands into a bucket of cold water can trigger brown fat into calorie-burning action. Likewise, exercise in the cold can boost the fat-burning effect, one reason to turn the thermostat down and go out for a stroll on a cold winter’s night.