Scientists Explain Age-Related Obesity: Brown Fat Fails
January 17, 2014
Story at-a-glance
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As you get older, the activity of heat-generating,
calorie-burning brown fat is reduced
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This “failing” of brown fat is likely a key reason why there’s a
tendency to gain weight with age
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Slender people tend to have more brown fat than obese people,
and young people have more than the elderly
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Exposure to cold temperatures and exercise can help you to
increase your body’s activation of brown fat and may even turn
“bad” white fat into beneficial brown fat
By Dr. Mercola
When it comes to body fat, most Americans are concerned
with losing as much of it as possible. But this is
referring to white fat, which is the type that typically
accumulates on your belly and thighs.
Another type of fat is called brown fat, and emerging
research suggests that many people may be better off
increasing this beneficial type of fat. In fact, a new
study revealed that one reason you may have trouble staying
slim as you get older is because your levels of brown fat
generally decrease with age.
Are Falling Brown Fat Levels Responsible for Middle-Age
Spread?
Most people are familiar with age-related weight gain or
obesity. As you get older, you have to watch your diet more
closely and stay more active just to maintain your weight,
let alone lose any. Meanwhile, when you were in your 20s,
you could eat whatever you wanted without gaining a pound.
One reason for your body's propensity for weight gain as
it ages may have to do with decreasing levels of brown fat,
which occurs naturally as you get older. Brown fat is a
heat-generating type of fat that burns energy
instead of storing it, and this may have important
implications when it comes to weight loss.
It is colored brown because it is loaded with
mitochondria that convert the fat directly to energy to
produce heat. Researchers initially thought its primary
function was to help produce heat in the absence of
shivering.
Human newborns have a generous supply of brown fat to
keep warm, but by adulthood they lose most of their stores
of it. Until just a few years ago, it was thought that
adults had no brown fat at all, since you can adequately
shiver as a way to keep warm (babies, on the other hand,
cannot).
Newer research revealed that not only do adults have some
brown fat, but it appears to have physiological roles beyond
heat generation. These roles are just now beginning to be
explored…
In one recent study, mice that had a gene known as
platelet-activating factor receptors (PAFR) knocked out
became far more obese with age than the normal control mice.
The PAFR gene is responsible for inflammation and fat
transfer, and it's thought that deactivating it impaired the
function of brown fat, causing the mice to become quickly
obese.1
The researchers are looking into ways to
pharmacologically target the pathway that might deactivate
the PAFR gene in humans, thus contributing to obesity.
However, there are likely a number of natural ways to boost
your brown fat stores.
As for what this has to do with your age… it's known that
as you get older, the thermogenic activity of brown fat is
reduced, similar to what happened with the mice in the
study. This "failing" of brown fat is likely a key reason
why there's a tendency to gain weight with age. The
FASEB Journal's editor-in-chief noted:2
"A common complaint is that older people have to
work twice as hard with their diets and exercise to get
half of the results of younger people. Now we have a
much better idea why this is the case: Our brown fat
stops working as we age."
Characteristics of Those with Higher Levels of Brown Fat
Brown fat has been located in the neck area, around blood
vessels (helping to warm your blood), and "marbled" in with
white fat in visceral fat tissue. It's now thought that
virtually everyone has small amounts of brown fat in their
body,
Although certain groups of people tend to have more brown
fat than others. Interestingly, it appears that the more
brown fat, or the more activated brown fat, the
better, as there are direct correlations between the
activation of brown fat and metabolic measures of good
health. For example:
- Slender people have more brown fat than obese people
do
- Younger people have more brown fat than elderly
people
- People with normal blood sugar levels have more
brown fat than those with high blood sugar
Women also tend to have more brown fat than men, and
people taking beta blocker drugs to treat high blood
pressure have less active brown fat. The latter is likely
because catecholamines, which are hormones released as part
of your body's natural "fight or flight" response, are known
to activate brown fat, but beta-blockers block
catecholamines, thereby suppressing the activation of
beneficial brown fat.3
A 'Master Switch' for Brown Fat Production?
Over the past five years, Bruce Spiegelman, PhD, with
Harvard University's Dana-Farber Cancer Institute, and his
research team has published at least five studies4
on the topic of brown fat, and in one, they identified a
sort of master switch that promotes the production of brown
fat. In 2008, they showed that the molecular switch, known
as PRDM16, regulates whether immature cells will turn into
brown fat or into muscle cells. In an interview
with WebMD, Spiegelman said:5
"We showed that brown fat and white fat have
completely different origins. Brown fat is derived from
muscle. That was a huge surprise."
Another set of researchers from Harvard's Joslin Diabetes
Center found another trigger for brown fat—a protein called
BMP-7, which also promotes bone growth.6
The researchers discovered that this protein acts as a
growth factor for brown fat. Mice treated with BMP-7 protein
grew up to have more brown fat than untreated mice, and the
treated mice also used up more energy. Needless to say,
researchers are excited about the potential for a medical
intervention that can help people develop more brown fat.
But I would be cautious of any solution in a pill form.
Instead, I'd suggest trying out some of the non-invasive
methods that have been found to promote brown fat production
and its activation.
Cold Temperatures May Activate Your Brown Fat
It appears that spending time in cold temperatures may be
a valid, albeit uncomfortable, way to activate your brown
fat. The finding is so strong that some researchers on the
subject joked they would be opening a "frosty spa."7
In one study, scientists found that they were able to
activate brown fat in adult men by exposing them to cold
temperatures.8
The men burned more calories when cooled and lost white fat,
the kind that causes obesity. According to the study's
authors:
"Does human brown fat actually combust fat to
release heat? ... Ouellet et al. demonstrate that
metabolism in brown fat really is increased when adult
humans are exposed to cold. This boosts the possibility
that calorie combustion in brown fat may be of
significance for our metabolism and, correspondingly,
that the absence of brown fat may increase our proneness
to obesity …"
Swedish research published in 2009 also found that cold
temperatures increased the activity in the subjects' brown
fat regions.9
In fact, cold-induced glucose uptake was increased by a
factor of 15! Based on animal models, researchers estimated
that just 50 grams of brown fat (which is less than what
most study volunteers have been found to have) could burn
about 20 percent of your daily caloric intake—and more if
"encouraged." Tim Ferriss, author of The Four-Hour Work
Week, gave the following suggestions for putting this
into practice (they range from easy to hard core):
- Place an ice pack on your upper back and upper chest
for 30 minutes per day (you can do this while relaxing
in front of the TV for example)
- Drinking about 500 ml of ice water each morning
- Cold showers
- Immersing yourself in ice water up to your waist for
10 minutes, three times per week. (Simply fill your tub
with cold water and ice cubes)
Exercise May Turn 'Bad' White Fat Into 'Good' Brown Fat
In one mouse study, the animals converted white fat into
brown fat simply by exercising. The study, published in the
journal Disease Models and Mechanisms10
in May 2012 found that, during exercise, the animals'
muscles released an enzyme called irisin, which triggered
the conversion of white fat cells to brown.
It still wasn't for certain whether this would hold true
in humans… until preliminary studies presented at the 2013
annual meeting of the American Diabetes Association showed
that both mice and men experienced beneficial "browning" of
fat following exercise. Among men, the benefits were found
after 12 weeks of training on an exercise bike. One of the
researchers, a postdoctoral fellow at Joslin Diabetes
Center, said:11
"Our results showed that exercise doesn't just
have beneficial effects on muscle, it also affects fat…
It's clear that when fat gets trained, it becomes
browner and more metabolically active. We think there
are factors being released into the bloodstream from the
healthier fat that are working on other tissues."
Getting a Good Night's Sleep, with Proper Melatonin
Production, May Also Be Important
Consuming melatonin stimulates the appearance of "beige"
fat, which,
similar to brown fat, also helps your body to burn
calories rather than store them. This, the researchers of
one study believe, may explain why melatonin helps control
body weight, along with its metabolic benefits.12
Science Daily reported:13
"The study… showed that chronic administration of
melatonin sensitizes the thermogenic effect of exposure
to cold, heightens the thermogenic effect of exercise
and, therefore, constitutes excellent therapy against
obesity. The fact is that one of the key differences
between 'beige fat,' which appears when administering
melatonin, and 'white fat,' is that 'beige fat' cell
mitochondria express levels of UCP1 protein, responsible
for burning calories and generating heat."
Though this wasn't discussed in the study, it's also well
proven that lack of sleep is linked to obesity, while if
you're not getting enough sleep, there's a good chance your
melatonin production is not up to par either. The
disturbance to your melatonin levels caused by lack of sleep
(and exposure to
light during the night) may be one more reason why it
leads to weight gain, and this could have far-reaching
impacts on your health.
Another Powerful Trick for Fighting Age-Related Weight Gain
We've covered exercise, proper sleep, and, potentially,
cold water immersion therapy as methods for activating your
brown fat for better weight management. Another powerful
tool that can help you to fit back into the jeans you wore
in high school?
Intermittent fasting, otherwise known as scheduled
eating.
Based on my own phenomenal experience with scheduled
eating, I believe it's one of the most powerful ways to
shift your body into fat burning mode and improve a wide
variety of biomarkers for disease. The effects can be
further magnified by exercising while in a fasted state. For
more information on that, please see my previous article "High-Intensity
Interval Training and Intermittent Fasting - A Winning Combo."
To get started, consider skipping breakfast and avoid
eating at least three hours before you go to sleep. This
should effectively restrict your eating to an 8-hour window
or less each day. When you do eat, make sure to minimize
carbs like pasta, bread, and potatoes. Instead, exchange
them for healthful fats like butter, eggs, avocado,
coconut oil, olive oil, and nuts—essentially the very
fats the media and experts tell you to avoid.
You may also want to
restrict your protein a bit if you're typically a big
meat eater. I strongly suggest eating only high-quality
pastured protein, and limiting it to about one gram of
protein per kilogram of lean body mass (about one-half gram
of protein per pound of lean body weight) may be appropriate
for most people. (Note: if your body fat mass is 20
percent, your lean mass is 80 percent of your total
body weight.)
These kinds of food choices, in combination with
intermittent fasting, will help shift you from carb-burning
to fat-burning mode, so you can stay fit and trim regardless
of your age.
© Copyright 1997-2014 Dr. Joseph Mercola. All Rights Reserved.
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