Vox
By Julia Belluz
DECEMBER 9, 2018
As
the temperature drops this time of year, the rich, comforting foods of
winter seem just right. But as we lay about, full from our heavy winter
meals, we may also dream about how to quickly burn off those extra
calories.
One idea that gets bandied about is that all you have
to do is exercise outside in the cold. You can find it in magazines,
newspapers, and maybe your email inbox—we recently got a press release
from the University at Albany titled, “Winter Exercise Burns More
Calories, Especially for Women.”
It is true that a cold body uses
more energy to keep itself warm than a warm body. But alas, exercising
in the cold isn’t the fabulous calorie burner you may like to think it
is. Before we get to why, let’s look at the reason this idea seems so
intuitive and appealing.
The body does use more energy to stay warm when it’s cold out
First
consider a process called thermogenesis. Your body creates heat when
it’s cold (usually below 32 degrees Fahrenheit but in a person wearing
light clothes, it can start at temperatures as high as 70).
One
way is by shivering—where the muscles involuntary contract to generate
warmth, and defend your body temperature (98.6 degrees Fahrenheit). Or
you may begin to activate “brown fat,” the kind of fat tissue whose main
function is heat production. Unlike white fat, which stores heat to
keep you warm, brown fat burns calories to generate heat.
“The
analogy might be [an] oil tanker that drives on the highway compared to a
sports car,” explained Aaron Cypess, a metabolism and brown fat
researcher at the National Institutes of Health. “They both have fuel,
or fat, but the oil tanker stores it for use later, and that’s the white
fat. The sports car stores fuel to burn it, and that’s the brown fat.”
The process of breaking down these lipids to release heat, and warm you
up is called “non-shivering thermogenesis.”
Both shivering and brown fat activity increase your energy expenditure, causing you to burn more calories in cold temperatures.
“You
don’t even know [it’s] happening,” explained Herman Pontzer, an
associate professor at Hunter College who studies energetics. “It’s
below the radar of your conscious thought, but it’s there ticking away.”
Exercise can produce a lot of heat on its own
Now
here’s the rub: These processes only kick in to keep you warm when
you’re truly cold. But once you start exercising—running or
cross-country skiing, for instance—outside, you’re going to start
generating heat from the physical activity. And the exercise alone may
give you enough heat that your body wouldn’t burn any extra calories
through shivering and brown fat.
That’s why you can go running in
very cold temperatures wearing a light sweater and pants, but if you
were just sitting around outside in the same cold climate, you’d need to
bundle up in a heavy jacket and hat, or you’d start to shiver, to stay
warm, Pontzer explained.
“The best way to use the cold to burn
more calories would be to not exercise while you’re outdoors,” Pontzer
added. “You’d get your brown fat cooking and making heat, and might even
start shivering, all of which burns calories.”
Now, it is
possible to get those energy-burning heating processes going while
exercising. Cypess imagined a scenario where a person is exercising in
subzero temperatures, and wearing light enough clothes, that the
exercise alone isn’t keeping him warm, and thermogenesis kicks in.
But
even in that case, you’d only burn a few additional calories at best,
Cypess said. In studies where he’s put participants in cold rooms for
entire days, they burned off an additional 150 to 200 calories. Again,
that’s a full day of cold—not an hour’s worth of outdoor activity.
All physical activity only accounts for a small portion of energy burn
Of
course, the most important thing to remember if you’re trying to make
up for heavy meals is that physical activity makes up a surprisingly
small portion of your total energy burn.
There are three major
components to how many calories you burn off in a day: 1) your basal
metabolic rate, or the energy used for basic functioning when the body
is at rest; 2) the energy used to break down food; and 3) the energy
used in physical activity. For most people, the basal metabolic rate
accounts for 60 to 80 percent of total energy expenditure. Digesting
food accounts for about 10 percent. That leaves only 10 to 30 percent
for physical activity, of which exercise is only a subset. Thermogenesis
is an even more minor player, Cypess said, usually accounting for less
than five or 10 percent of your total energy expenditure (depending on
how much time you’ve spent in the cold).
When I asked Cypess if
he had any advice about exercising and temperature, he said he’d
recommend against the extremes—even extreme heat. In very hot
temperatures, during activities like hot yoga, all the sweating you do
is simply losing water, and that the sweating process doesn’t burn off
extra calories. “Exercise at a temperature where you’re not sweating too
much,” he summed up.
So if you overeat, the best thing to do is
probably focus on having smaller meals later to make up for your
indulgences. Exercising, even in cold weather, isn’t going to cut it
alone.
Questions Using Close Reading and Critical Thinking:
- The first section of an article should answer the questions “Who?”, “What?”, “When?”, and “Where?” Identify the four Ws of this article. (Note: The rest of the news article provides details on the why and/or how.)
- Does this article have any bias? Why or why not?
- Reread the second paragraph. What do you think the phrase “bandied about” (in the first sentence) means? What clues from the paragraph helped you come to that conclusion?
- Summarize and explain what your body does in the cold that causes you to burn more calories.
- “Now here’s the rub” is a transitional phrase (brought to us from Shakespeare’s Hamlet). Look closely at the information presented before and after the phrase. What do you think it means? Name two other transition words or phrases that could have also been used here to effectively communicate the author’s point.
- Why does Aaron Cypess advise against exercising in extreme temperatures?
- How is the information in the article organized (description, sequence/order, problem/solution, cause/effect, compare/contrast)? Do you think this organization was effective? Use specific details from the article to support your position.
Click here to view more: www.vox.com/2017/12/23/16774320/exercise-in-cold-burn-more-calories