Cold exposure has been shown to trigger fat loss by altering gut microbes and stimulating the production of brown adipose tissue. Studies found that cold temperatures cause a shift in gut microbes that prevents weight gain in mice and promotes the formation of "beige fat" which regulates energy balance. Cold exposure also has the ability to rapidly change 30% of white adipose tissue into brown adipose tissue. Regular cold showers are recommended to mimic these effects and stimulate brown fat over time to raise metabolism.

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FAT LOSSTHE UNEXPECTED
TEMPERATURE
THAT COULD AID
IN WEIGHT LOSS
54 June/July 2016

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Megan P
atiry
It’s a meme floating through the social media universe that seems to resonate with most of us.
One of the constant measures of an effective workout, after all, has always been how red-faced
and sweaty we are at its conclusion. Soaked-through gear and a dripping brow definitely cause
us to feel as if we’re blasting away fat faster than if, say, we were running sprints in sub-zero
temperatures. However, it turns out that this chill factor might be the real burner when it
comes to fat loss.
“Sweat is just fat crying.”
While it might seem counterintuitive at first glance, a
study conducted in December 2015 confirmed that fat loss
is triggered in response to cold temperatures, while also
showing that cold exposure has the ability to mimic the
effect of exercise and improve glucose metabolism.1
The
mechanism boils down to an alteration in our trusty gut
microbes and their influence on different types of adipose
tissue, aka fat.
Brown for the Burn
All mammals have two types of adipose tissue: white and
brown. White adipose tissue is the “energy-storage” tissue that,
when accumulated in excess, causes obesity. Brown adipose
tissue, on the other hand, is found mostly in young children, as
it effectively generates heat to protect them from extreme cold.
Researchers claim it to be “essentially nonexistent and without
physiologic relevance” in adults, but have discovered that if we
(adults) had more brown adipose tissue, we could effectively
spur our metabolisms: “estimates suggest that if it were present,
as little as 50g of maximally stimulated brown adipose tissue
could account for up to 20 percent of daily energy expenditure
in an adult human.”1
As we know, increased energy expenditure equals more
fat burned. So, if we could somehow stimulate our bodies
to produce more brown adipose tissue than white, we’d
theoretically be on the path to greater fat loss—and this is
where our gut microbes and chilly temperatures come in.
Researchers decided to test the link between intestinal
bacteria, weight and temperature, and discovered that just 10
days of exposure to cold temperatures (6°C/43°F) caused “a
major shift in the composition of gut microbes while preventing
weight gain” in mice.1
These cold-exposed microbes were then
implanted into mice raised in a germ-free environment, where
researchers found that the transplanted microbes improved
glucose metabolism and caused weight loss “by promoting the
formation of beige fat.”
“These findings demonstrate that gut microbes directly
regulate the energy balance in response to changes in the
environment,” said senior study author Mirko Trajkovski of the
University of Geneva. This energy regulation is so direct that
just a three-hour period of cold exposure burned 250 extra
calories through the activation of brown fat.2
Another piece of support for cold exposure comes from a
separate study conducted in January 2015, which showed that
white adipose tissue can also turn into brown adipose tissue.
Researchers found that roughly “30 percent of cells that appear
to be white adipocytes before cold stress can rapidly turn on
the brown adipocyte program following cold stress.” In other
words, cold stress has the ability to rapidly change 30 percent
of our white adipose tissue into brown, metabolic-enhancing
adipose tissue.3
Nutrients Receive a Not-So-Chilly Welcome
Aside from fat loss, cold exposure also has another trick up
its sleeve. Researchers found in the same study that cold-
exposed gut microbes cause intestinal growth, which results
in more nutrient absorption due to the greater surface area of
the intestines.
“These findings demonstrate that gut microbes enable
mammals to harvest more energy from food as a way to
adapt to the increased energy demand associated with long
periods of cold exposure, thereby helping to protect against
hypothermia,” Trajkovski said. “We were surprised to see that
gut microbes had such dramatic effects on the structure and
function of the intestine.”
Getting Cold
Mimicking the effect of these studies requires one strategy
that you might not initially be in love with, but your brown-
adipose-producing microbes will: cold showers. Also referred to
in the medical field as a form of hydrotherapy or cold therapy,
the practice has been used medicinally in cultures around
the world for centuries. Hippocrates endorsed it as a cure for
inflammation and pain, while the ancient Romans reportedly
alternated bathing in hot water pools with taking a dip in the
frigidarium, or cold water bath.
While the ancients obviously used cold therapy for more than
fat loss, the same concept can be used to mimic the effect of
cold exposure seen in the above studies. Although the results
likely won’t be as drastic as spending 10 days—or even a
sustained three hours—exposed to cold, there is evidence that
shivering for just 10 to 15 minutes releases the same amount of
irisin, a muscle hormone triggered by exercise, as one hour of
moderate exercise.4
The goal with these showers (shivering included) is to induce
this effect by stimulating brown adipose tissue over time in order
to raise the metabolic rate. However, before you go leaping
into the iciest shower known to man, it’s important to know that
you should build up your tolerance to the showers by gradually
increasing the temperature from lukewarm to very cold to the
touch. Toggle between cold for two minutes, then warm for two
minutes, working your way up to a total of 10 minutes altogether
each time you shower.

4. If your resolve begins to fade once you start shivering, just
keep in mind that a study conducted in Scandinavia also found
that exposure to cold temperatures “increased the metabolic
rate of brown fat by fifteen fold, which could help a person drop
nine pounds in a year if sustained.”5
Interestingly, your resolve may begin to strengthen the longer
you stick with the showers. Studies of winter swimmers have
shown a marked decrease in “negative moods” and a decrease
in tension and fatigue.6
Exposure to cold stimuli has also been shown to reduce
stress,7
which, as we know, can be a major factor in losing
body fat. It appears that cold exposure activates the
sympathetic nervous system, thereby increasing the release of
norepinephrine—the adrenal hormone that can cause a mood
“lift” in depressed individuals. By feeling less stressed, we’re
also able to lower our cortisol levels, which has been linked to
lower levels of belly fat.
Echoing the words of Gerald Weissmann, MD, “If you
want to rev up your metabolism, don’t throw out your winter
coat just yet.”

COLD STRESS HAS THE ABILITY TO RAPIDLY
CHANGE 30 PERCENT OF OUR WHITE
ADIPOSE TISSUE INTO BROWN, METABOLIC-
ENHANCING ADIPOSE TISSUE.
56 June/July 2016
Megan Patiry is an inquisitive food and travel writer,
harboring an editorial love affair with the decadent, the
mysterious, and the nutritious. She is a dedicated Paleo
foodie, ancestral health devotee, certified Specialist in
Fitness Nutrition, certified Personal Trainer, and holds a
BA in English/Creative Writing.
MeganPatiry.Contently.com
REFERENCES
1 Cell Press. “Gut microbes trigger fat loss in response to cold temperatures.” ScienceDaily. 3 Dec 2015.
https://www.sciencedaily.com/releases/2015/12/151203135832.htm.
2 Oullett V, Labbé SM, Blondin DP, Phoenix S, Guérin B, et al. “Brown adipose tissue oxidative metabolism
contributes to energy expenditure during acute cold exposure in humans.” The Journal of Clinical Investiga-
tion. 24 Jan 2014. 122.2 (2012): 545–52. doi: 10.1172/JCI60433.
3 Federation of American Societies for Experimental Biology. “Exposure to cold reveals ‘switch’ that
controls formation of brown, white fat.” ScienceDaily. 5 Jan 2015. http://www.sciencedaily.com/releas-
es/2015/01/150105125908.htm.
4 Garvan Institute of Medical Research. “Embrace the cold: Evidence that shivering and exercise
may convert white fat to brown.” ScienceDaily. 4 Feb 2014. http://www.sciencedaily.com/releas-
es/2014/02/140204123619.htm.
5 Knox R. “Brown Fat: Don’t Try to Burn It.” NPR. 10 Apr 2009. http://www.npr.org/templates/story/story.
php?storyId=102964807.
6 Huttunen P, Kokko L, Ylijukuri V. “Winter Swimming Improves General Well-Being.” International Journal of
Circumpolar Health. 63.2 (2004): 140–4.
7 Shevchuk NA. “Adapted cold shower as a potential treatment for depression.” Medical Hypotheses. 70.5
(2008): 995–1001.
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