The
interesting take home is that the hunter gatherers were all thin
while effectively been more sedentary than we ever are. The
difference of course is in the quality of the carbohydrates and in
the application of short bursts of exertion.
More
seriously though we need to respect sedentary protocols and obviously
practice racket ball. Distance running has its own merits but is is
hardly the only way to physically prosper.
This
is a surprise to those of us who ever thought that our ancestors
entered a life of unrelenting toil because it has more rewarding and
it allows us to understand the reluctance of hunter gatherers to
adopt modernism. If your family has not gone hungry for little
effort for thousands of years, it is hard to merit a change.
It is
also noteworthy that 80 year old grandmothers remain strong and
vital.
Tanzania
Al Sears, MD
December 14, 2012
The
Hadza tribe, which I’m planning to visit in a few months, live near
Lake Eyasi, just south of the Ngorongoro crater in Tanzania.
I’m blessed to have been in Tanzania three times now. I was
lucky enough to meet with the Masai, the ancient hunter-gatherers who
shared with me all of their herbal knowledge.
I was also blessed to be able to visit the Ngorongoro Crater and
get a personal tour from the chief conservator of the crater. He told
me the inside story of how they take care of the biggest lions on the
planet.
And I also went to see Olduvai Gorge, the birthplace of humankind.
It’s one of the most important archeological sites in the world,
where the archeologist Mary Leakey discovered almost
2-million-year-old australopithecine pre-human remains.
It’s amazing one country has all those things in it... and now
I’m making plans to go back there to visit another ancient tribe of
hunter-gatherers.
Because after reading a recent article in The New York Times,
I’m definitely planning on seeing the Hadza people.
At the time I read the article, I was reading the latest research
on exertion and oxygen uptake for my new subscription
newsletter Confidential Cures.
I read a study called “Hunter-Gatherer Energetics and Human
Obesity” and noticed that the lead author had written an article
in The Times. His article is titled “Debunking the
Hunter-Gatherer Workout.”
The gist of it is that the author and his colleagues wanted to try
and figure out if a lack of physical activity is the reason that
modern human beings are fat. So they decided to measure calories
burned in a hunter-gatherer group in Africa and compare it to our
calories burned.
They looked at the Hadza from northern Tanzania, a group pretty
much untouched by the West, which is very rare in the modern world.
And they found that the Hadza didn’t burn more calories than we
do.1
I’ve visited many of these tribes myself, including the Batwa
and the Masai in Africa, and the Ashaninkas in South America. And
it’s not surprising that they don’t burn that many calories...
They don’t hunt that often. We push ourselves at a low
level of exertion all day long every day because of our busy
lifestyle. They sit back and pretty much lie around most of the
time.
The lead author went on to write in The Times that,
because we burn the same amount of calories, we are not fat due to
being sedentary... and that this debunks the hunter-gatherer style
workout.2
But what they studied has nothing to do with proving why people
are fat. The researchers never looked at the quality of the
Hadza’s exertion, or the intensity of it, or even what kind of
exertion it was... which makes all the difference.
What they should have done was open their eyes and look around and
see that the Hadza were all thin. And being thin is not about
burning calories. It’s about the kind of calories you take in, and
the way you exert yourself.
Compared to how hunter-gatherers ate, we more than doubled the
percentage of carbohydrates that we consume. Plus, the character of
the carbohydrate has changed to a much higher glycemic index.
Your body converts carbs into either sugar or fat. So if you
religiously follow the latest low-fat, high-carb diet, your waistline
will only get bigger.
And the modern notion of constant, low-level endurance exercise to
get in “the fat-burning zone” makes it worse. Exertion for short
periods and a total of less than 20 minutes, like I show you how to
do in my P.A.C.E. program, will use these carbs during
exercise and signal your body that you don’t need fat. You burn off
the fat after your workout while you replenish the carbs for your
muscles.
Debunking the
Hunter-Gatherer Workout
By HERMAN PONTZER
Published: August 24,
2012
DARWIN isn’t
required reading for public health officials, but he should be. One
reason that heart disease, diabetes and obesity have reached epidemic
levels in the developed world is that our modern way of life is
radically different from the hunter-gatherer environments in which
our bodies evolved. But which modern changes are causing the most
harm?
Many in public health
believe that a major culprit is our sedentary lifestyle. Faced with
relatively few physical demands today, our bodies burn fewer calories
than they evolved to consume — and those unspent calories pile up
over time as fat. The World Health Organization, in discussing the
root causes of obesity, has cited a “decrease in physical activity
due to the increasingly sedentary nature of many forms of work,
changing modes of transportation and increasing urbanization.”
This is a nice theory.
But is it true? To find out, my colleagues and I recently measured
daily energy expenditure among the Hadza people of Tanzania, one of
the few remaining populations of traditional hunter-gatherers. Would
the Hadza, whose basic way of life is so similar to that of our
distant ancestors, expend more energy than we do?
Our findings,
published last month in the journal PLoS ONE, indicate that they
don’t, suggesting that inactivity is not the source of
modern obesity.
Previous attempts to
quantify daily energy expenditure among hunter-gatherers have relied
entirely on estimation. By contrast, our study used a technique that
calculates the body’s rate of carbon dioxide production — and
hence the calories burned per day — by tracking the depletion of
two isotopes (deuterium and oxygen-18) in an individual’s urine
over a two-week period.
It was a testament to
the Hadza’s graciousness, and their years of friendship with
several of my colleagues, that they welcomed us into their camps and
participated in the study. As we sat back and observed, the Hadza
went about their normal routines.
The Hadza live in
simple grass huts in the middle of a dry East African savanna. They
have no guns, vehicles, crops or livestock. Each day the women comb
miles of hilly terrain, foraging for tubers, berries and other wild
plant foods, often while carrying infants, firewood and water. Men
set out alone most days to collect honey or hunt for game using
handmade bows and poison-tipped arrows, often covering 15 to 20
miles.
We found that despite
all this physical activity, the number of calories that the Hadza
burned per day was indistinguishable from that of typical adults in
Europe and the United States. We ran a number of statistical tests,
accounting for body mass, lean body mass, age, sex and fat mass, and
still found no difference in daily energy expenditure between the
Hadza and their Western counterparts.
How can the Hadza be
more active than we are without burning more calories? It’s not
that their bodies are more efficient, allowing them to do more with
less: separate measurements showed that the Hadza burn just as many
calories while walking or resting as Westerners do.
We think that the
Hadzas’ bodies have adjusted to the higher activity levels required
for hunting and gathering by spending less energy elsewhere. Even for
very active people, physical activity accounts for only a small
portion of daily energy expenditure; most energy is spent behind the
scenes on the myriad unseen tasks that keep our cells humming and our
support systems working. If the Hadza’s bodies somehow manage to
spend less energy in those areas, they could easily accommodate the
elevated energy demands of hunting and gathering. And indeed, studies
reporting differences in metabolic-hormone profiles between
traditional and Western populations support this idea (though more
work is needed).
Our findings add to a
growing body of evidence suggesting that energy expenditure is
consistent across a broad range of lifestyles and cultures. Of
course, if we push our bodies hard enough, we can increase our energy
expenditure, at least in the short term. But our bodies are complex,
dynamic machines, shaped over millions of years of evolution in
environments where resources were usually limited; our bodies adapt
to our daily routines and find ways to keep overall energy
expenditure in check.
All of this means that
if we want to end obesity, we need to focus on our diet and reduce
the number of calories we eat, particularly the sugars our primate
brains have evolved to love. We’re getting fat because we eat too
much, not because we’re sedentary. Physical activity is very
important for maintaining physical and mental health, but we aren’t
going to Jazzercise our way out of the obesity epidemic.
We have a lot more to
learn from groups like the Hadza, among whom obesity and heart
disease are unheard of and 80-year-old grandmothers are strong and
vital. Finding new approaches to public health problems will require
further research into other cultures and our evolutionary past.
Herman Pontzer is
an assistant professor of anthropology at Hunter College and a
co-founder of the Hadza Fund, a nonprofit organization that
supports the Hadza population.
No comments:
Post a Comment