Could your warm and cosy home be hindering your weight-loss efforts?
Dutch researchers say keeping temperatures a little chillier at home and the
office might be an additional weapon in the fight
"What would it mean if we let our bodies work again to control body temperature?"
said study author Dr Wouter van Marken Lichtenbelt, an associate professor in
the department of human biology at Maastricht University Medical Centre.
Mild cold temperatures
In the new study, his team explored whether frequent exposure to mild cold
temperatures would boost the body's energy expenditure. In other words, would
peoples' metabolisms ratchet up a notch, burning more calories if they lived on
the cool side?
Prior studies have shown that shivering increases heat production in people,
according to the study. And one Japanese study found that people experienced a
drop in body
fat after spending two hours a day for six weeks at a temperature of about
17 degrees Celsius.
Of course, chilly temperatures can bring on the shivers. The researchers
said shivering is a short-term biological response to extreme cold that
protects humans from hypothermia,
or dangerously low body temperatures. More recent studies show that another
type of shivering, called non-shivering thermogenesis (NST) an animal response
to fighting milder cold temperatures also increases heat output, but not so
fast that a body can't keep up with producing heat.
"In most young and middle-aged people, NST increases by between a few
percent and 30% in response to mild cold exposure," the researchers said
in their report. "Thus, NST can have a physiologically significant effect
upon energy expenditure."
Burning more calories
Prior research from the Dutch team showed that people gradually acclimatise
themselves to cooler room temperatures. People who spent six hours a day at 15
degrees Celsius felt more comfortable and shivered less by the end of 10 days
in this environment, the researchers found.
The paper is largely based on theory, said Dr Mitchell Lazar, chief of the
division of endocrinology, diabetes and metabolism at the University of
"But there is certainly evidence in people as well as rodents to suggest
that reducing temperature makes the body burn more calories to keep up body
temperature," said Lazar, who was not involved in the new study.
So how much time sitting in a chilly room would it take to burn, say, 100 calories?
It's too early to know, said van Marken Lichtenbelt.
"We do have clear evidence that cold adaptation increases energy
expenditure," he said. "There is no doubt in this respect. How
pronounced these effects are in everyday life, especially in the long term, is
not yet known."
The researchers are planning long-term experiments that involve having
people live in cooler environments while tracking their weight over time.
"We will vary indoor temperature and weight, and many other health
parameters will be monitored," van Marken Lichtenbelt said.
Cold temperature training
"The other experiment... is 'cold-temperature training', also known as
'acclimatisation'," van Marken Lichtenbelt said. "This has been shown
to rev up brown fat in rodents, and it seems possible that it could do the same
Unlike white fat, brown fat burns calories instead of storing them. Some
studies have shown that brown fat has beneficial effects on blood sugar
tolerance, fat metabolism and body weight.
"It would be very interesting to do something like this in people who
are dieting and exercising to lose weight, to see if this strategy could
increase the weight loss or even allow the diet and exercise plan to
work," van Marken Lichtenbelt said. "We know that so many people
struggle with diet
and exercise alone."
Is it worth turning down the thermostat if you're trying to shed some
pounds? It's too soon to be certain that strategy would work, said Lazar, who
also is the director of the University of Pennsylvania's Institute for
Diabetes, Obesity and Metabolism.
"It would do no harm," he said. "It's worth a try for someone
who is having trouble losing weight by diet and exercise alone."