Have you turned on the heat in your house yet this fall?
For your waistline’s sake, you might want to hold off as long as you comfortably can (not difficult to do with our current warmish weather forecast) — and keep the temperature down once you do switch on your furnace or boiler.
It all has to do with brown adipose tissue (fat), which is not to be confused with so-called white fat. (Actually, it’s yellow.) Located under the surface of the skin, white fat is where our bodies store surplus energy (calories). Thus, it’s the fat we associate with being overweight or obese.
Brown fat is something different. It forms in small deposits in the neck, spine and upper back; it also co-mingles with white fat elsewhere in the body. Once thought to be physiologically unimportant, brown fat is now believed to be a kind of internal “furnace” that burns calories.
And that’s why keeping the thermostat on low might help the waistline, says Kobayashi. She supports her argument with a couple of recent studies, one from Japan and one from the Netherlands:
The new study from the Netherlands found that brown fat plays a role in what’s called ‘nonshivering thermogenesis’ — it burns calories to generate heat from within our bodies during exposure to cold. The researchers subjected a group of people to a 10-day cold acclimation programme (exposure to 15-16 degree C temperature for 6 hours per day) [59-61 degree F temperature], and found significant increases in brown fat metabolic activity and less shivering among the participants, who reported feeling less sensitive to cold at the end of the study. Therefore, regular exposure to cold makes brown fat more efficient in keeping us warm — it achieves this through increased nonshivering thermogenesis, resulting in less of a need to shiver. …
In the Japanese study, the investigators exposed healthy human subjects to cold (17 degrees C) [62 degrees F] for two hours per day for 6 weeks. They found an increase in brown fat activity and energy expenditure, and a decrease in body fat mass at the end of study. This means that getting brown fat active through cold exposure is actually effective in reducing body fat.
As I’ve pointed out here before, it’s unclear just how big a role brown fat plays in weight maintenance. The research on this topic is in its infancy. You’d be much more successful at maintaining a healthy weight by increasing your physical activity and modifying your diet, particularly by reducing your intake of sugar and other unrefined carbohydrates.
Still, encouraging your brown fat to become more metabolically active may help — and, as Kobayashi notes, it offers other benefits as well, such as saving money.
“Keep your hand off the thermostat,” she advises. “Let yourself be slightly cold — just outside of the comfort range that the human body is physiologically conditioned to remain at, which is around 23 degrees C [73 degrees F]. There’s no need to torture yourself — around 17 degrees C [62 degrees F] will suffice. You will burn calories, and according to the scientific evidence, you will eventually get used to it and feel the cold less. And yes, you will definitely save money on heating while helping out the environment at the same time.”