Every winter you can guarantee you’ll see a headline – or 20 – suggesting you pull on your sneakers on the coldest morning and get exercising because you’ll burn more calories if it’s nippy outside.
The idea comes from the fact that when we are cold – particularly when we are shivering – our body uses more energy to keep us warm, namely through muscle clenching.
So the theory goes that if you added the calorie-burning of exercise to the calorie-burning of being cold, you’d get a double-whammy calorie burner.
Unfortunately, experts tell 9Honey Coach that’s probably taking the science a tad too far.
“When we get cold, one of the ways we defend our body temperature is to shiver, which uses oxygen and therefore uses energy to generate those contractions,” explains Dr Ollie Jay, a thermoregulatory physiologist from the University of Sydney.
And exercising does the same thing.
“You can do that either through physical activity and contracting your muscles or if you’re not moving, you’ll start shivering a little bit and that will do the same thing,” Dr Jay explains.
So effectively it’s a one-or-the-other situation – exercising doesn’t compound the effects of shivering in the cold.
That said, you should definitely keep exercising in the cold because shivering won’t burn nearly the number of calories that running will.
“The most intense shivering recorded has been up to five times the resting metabolic rate,” Dr Jay explains.
“But if you go for a run and you’re relatively fit, you’re going to be at 10 times the metabolic rate at least.”
If you want to take advantage of the calorie-burning aspect of being cold, you need to make the most of it when you’re sitting still, either by dialling down the heating so you feel cooler or having a cold shower – this has to do with brown fat activation.
Unlike the “white” fat we’re familiar with that makes our flabby bits, brown fat is “biologically active” and kicks into gear to help us warm up in the cold.
“Intermittent cold exposure can increase brown fat abundance and may have a beneficial effect on metabolism,” Dr Paul Lee, a clinical scientist at the Garvan Institute of Medical Research, told Coach recently.
“Because of this energy-burning nature of brown fat, individuals with more brown fat are leaner.”
That said, experts say you’d need cold exposure for several hours a day to get noticeable metabolic benefits.
So the moral of the story seems to be to keep exercising in winter — not just because it’s cold but because exercise is good for you, whatever the weather.