WEBVTT

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[music]

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For about 99% of our time on this planet
we lived as hunters and gatherers

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when we needed food we just set
off in search of wild game,

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wild plants, fruits and vegetables. It Was
pretty healthy stuff and you\'ve got to exercise.

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There were no convenience foods I mean how
convenient is it when your dinner is running away

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from you at 20:00 miles an hour. Our appetites
were formed in that ancestral environment

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over millions of years
of evolutionary history

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we developed taste mechanisms that status towards
foods that were essential for our survival,

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sweet nutritious fruits,
salt and of course fat.

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[music]

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So when you take a bite out of a hot dog
or a stake take a mouthful of ice cream

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or open a pack of chips you are in
a sense taking a trip back in time

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these foods from the supermarket age
but our appetite for them was formed

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by the stone-age, our
cravings for sweet, salt

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and fats are ancient, written in our genes.

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In the desert of Central Arizona

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this evolutionary story of diet
and destiny has come full circle.

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[music]

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This is the Salt River Reservation

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home to the Pima Indian tribe, the Pimas
have made a living in this rugged desert

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for thousands of years helped by
what scientists call a thrifty gene.

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It enabled them to survive
the feast and famine cycles

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of desert life by efficiently gaining
weight during times of plenty

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storing fat to use as fuel
when times were tough.

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You see San Diego biochemist Paul saltman.

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Now over the centuries of the habitation
of those deserts by these Indian people,

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the individuals who survived the
most effectively with those who had

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the most efficient metabolic rate who
could store everything that they ate

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and store it as fat so that when the jack
rabbits weren\'t running or the rivers were dry,

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that they could live off their
own body fat as depot fat.

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But food is no longer in short
supply on the reservation,

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and once advantages thrifty
gene has backfired.

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Today, obesity runs rampant here, at least
three quarters of the tribe is afflicted,

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resulting in an epidemic of
diabetes and hypertension.

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The Pimas or a case study, you know, obesity,
a problem that has surfaced since the tribe

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shifted to a modern menu of saturated
fats and refined calorie rich foods.

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Dr. Eric Ravussin is with the
National Institutes of Health.

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This is what we call a gene
environment interaction.

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Basically, the environment selected for
a more efficient use of the calories

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when with this dramatic life
change, lifestyle change,

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uh… the Pimas were exposed
to plenty of food,

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less physical activity, and still
with their genetic background

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in this environment, they start to
grow and get heavier and heavier.

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In a sense, the Pimas are victims
of what was once a beneficial,

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evolutionary adaptation that dates back
to a time when ancestral hunter gatherers

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roamed the earth in search of food.
Then, a kind of survival

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of the fattest was the lord of the
land, meals were literally on the run.

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And the meat section put up a fight.

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Our ancestors relied on
wild game, very lean meat

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that was only perhaps 4% fat that\'s about seven
times less fatty than most supermarket beef.

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Wild fruits, vegetables, grains, and nuts,

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applied dietary fiber, protein
and other essential nutrients.

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Compared with today\'s refined
foods items on the Stone Age menu

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contain far fewer calories, but mouthful
so obesity was not an occupational hazard

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for hunter gatherers. On the contrary,
energy rich fat was a kind of luxury item

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and insurance policy against famine.

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But for modern hunter gatherers, what
was an advantage in the lean times

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is a liability and fat city.

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According to reports by the Surgeon General
and the National Research Council,

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it\'s time to stop mincing words.
UCLA nutritional research, Jay Kenny

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works on the fat frontline at the
Pritikin longevity Center in Los Angeles.

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At least one out of every three people is on a diet at
least once a year and yet all of this calorie counting,

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worrying about how much you\'re eating, worrying
about why you\'re eating more than you should,

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all of that is getting us nowhere,
we\'d be getting as a population,

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we\'re getting fatter each year, even though we\'re counting
calories more worrying about how much we\'re eating

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and worry about why we\'re eating it.

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If you\'re carrying a spare tire
around your metal, you\'re not alone.

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According to some estimates, two
thirds of Americans are overweight

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and if you add it all up, it comes
to more than two billion pounds.

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Convert that to its energy
equivalent and you\'d have

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enough gas to power about a million automobiles
for a year. Now, that\'s a lot of energy

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going to waist and hips and thighs

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and all those other places we store fat. But
our weight problem is no laughing matter

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of major concern are the one in eight
Americans who are considered obese

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20% above their ideal body weight.

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These people are at higher risk
for diabetes, cancer, stroke,

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and heart disease. Four of the
nation\'s leading killers.

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Scientists no longer regard obesity as just a
weakness in willpower, but rather a disease

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with complex environmental
and genetic underpinnings.

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Louisiana state university
researcher George Bray.

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It\'s very clear that the type of diet influences whether
you get fat or not. We know that in experimental settings

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if animals have a choice of foods,
or if they have a high fat diet,

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they\'re much, much more likely to become
overweight, then if they have a relatively simple

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or a high carbohydrate diet.
So diet not only for animals,

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but we think for humans as well is a very important
determinant of whether your genetic background

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will lead to your getting fat or not.

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The biochemical recipe for each
of us is written in our genes,

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in our DNA. Some of the ingredients
are fixed. In my case,

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for example, the recipe called for blue eyes, but
nowhere was it written that I had to be exactly

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six feet tall and weigh 180 pounds.

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That\'s the result of an interaction
between my genes and the environment.

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Obviously, there are some limits set by the genes that\'s why
I couldn\'t be seven feet tall, but what about my weight

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other perhaps genes for fatness
that no matter what I tried to do

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still tip the scales.

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Research reported during May 1990, in
the New England Journal of Medicine

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supports the notion that weight gain may
be influenced more by what\'s in our genes

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than what\'s on our plate. One
study found that identical twins

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show little difference in bodyweight, whether
or not they were raised in the same family.

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In another experiment for four
months, pairs of lean twins

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were fed an extra 1000 calories daily,
some pairs gained as little as nine pounds

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others as much as 29. The key point is this

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genetically identical twins in each pair
showed virtually identical weight gains,

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despite the environment they were redeemed, suggesting
that obesity has a strong genetic component

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although both studies strengthen the
case for a link between faith and fat,

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heredity is not always destiny.

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For example, if there are populations around the
world, such as the Chinese or most African populations

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where obesity doesn\'t develop and yet
the same people, blacks and Asians,

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when they move to the United States adopt our high fat
diet and are inactive lifestyle, they become obese.

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So it\'s very clear that the same set of genes
in one circumstances will produce obesity

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and in another set of
circumstances it will not.

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Mixing fat loving jeans with an
unprecedented access to excess

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may be a recipe for disaster. A recent study by
Cornell University biochemist Colin Campbell,

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comparing us and Chinese diets underlines

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the dangers of our Western
love affair with fat.

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Although the Chinese
consume 20% more calories,

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Americans are the ones with
the weight problem, why?

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Probably, because the Chinese eat only a third
as much fat yet twice the starch that we do.

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The study also found that in
different regions of China

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increased fat consumption corresponded
with higher rates of obesity

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and related diseases. Our diet, however,

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which is rich in meat, and dairy
products, contains at least 30% fat.

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So it comes as no surprise that
our rates of heart disease,

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diabetes and stroke are among the highest
in the world. The twins research

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and particularly the Chinese study, reinforce
the opinion that life in the fat lane

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can be dangerous. It is not how much
you eat and it is not why you eat,

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it produces obesity, it is what you eat?
When we eat a high fat,

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high refined carbohydrate
diet, a lot of fat,

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sugar foods and people know what they
are ice cream, cheese cake, candy bar,

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when you\'re eating food like that, you\'re going
to become obese particularly if you are inactive

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if you have any genetic predisposition
towards obesity at all.

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What is it about eating fat
that fills us with fat?

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Well, first, it\'s loaded with calories,
a tablespoon of vegetable oil,

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a fat contains 135 calories,
a tablespoon of sugar,

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a carbohydrate contains only 48.

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But there\'s an extra twist even if you balance for
calories the fat in your food is more easily converted

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into fat on your body
endocrinologist, Frank Greenway.

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It\'s much easier for the body to take fat

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and just sort of slip it in to the fat cells,
it doesn\'t have to change it very much

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it only loses a very small percentage
of the energy but with carbohydrates,

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starches and sugars, it has to break them
all the way down to… to two carbon units,

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and then build it up in the fat
and it loses 25% of that energy

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in doing so and so it\'s a
less efficient process.

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If it seems unfair that you\'re one of those people
who seems to gain weight just looking at fatty foods

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while you\'re thin friends can eat
anything and not gain weight.

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Think about it this way,
in evolutionary terms,

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you who wants the success story,
you store fat efficiently.

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Your friends actually burn up nine times as
much energy making muscle instead of fat.

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If there\'s a famine, there history.

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Trouble is times have changed
after we invented agriculture,

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domesticated animals and finally learned
how to refine and mass produce foods,

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we began to labor under the
weight of our genetic past.

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So now there\'s a new skinny on fat.

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To understand it, let\'s take a
closer look at metabolic rate,

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which plays a major role in
determining who\'s fit and who\'s fat.

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It\'s the speed at which calories
are burned to provide energy.

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Metabolic efficiency is influenced by
a number of factors including age,

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activity, diet and body composition.

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Metabolism operates a bit like an
internal engine, converting fuel

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into energy as its services
the needs of ourselves.

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For some people, it functions
at a rapid, inefficient pace,

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spending calories instead of saving them.
Since muscle

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burns more calories than fat. People
with a high proportion of muscle mass

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tend to have a quick metabolic rate.

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For others with a slower and more efficient
metabolism like the Pima Indians

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fewer calories are burned, what\'s
left over is broken down into fat

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and stored in the body.
Differences in metabolic rate

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may explain why some people
gain and others maintain,

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even when eating hundreds
of extra calories.

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So weight control is not so much about
the number of calories you consume,

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but how many you eat in relation to
your metabolism. There are some people

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who are obese who don\'t appear to eat a lot but in point
of fact, relative to their inherited body metabolism

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is too much and those
people have to come down

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because whether their genes
say, be fat or be thin,

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their body responds to the fatness by all
of the characteristic diseases of obesity.

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This may not look

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much like a human body, but it\'ll give us some
clues about how the body regulates weight.

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Imagine this is your daily
diet and this is you.

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Some researchers have suggested that we
have evolved the kind of internal mechanism

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that tends to keep our weight fairly constant. Although it\'s
still controversial the idea of returning to a target weight

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that they call a set point
might work like this.

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This is energy in the calories
you eat, and this is energy out

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when they balance your weight stays level.
If you increase the amount of calories

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more than the body can use
your metabolic rate increases

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to burn off the excess and return to the
set point level. If you go on a diet

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and cut back on calories, the opposite happens
your body survival mechanisms kick in

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and try to conserve that precious fat.

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Experiments with laboratory animals
appear to support the set point theory.

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Genetically identical rats for example,

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offered an unlimited amount of Chow tend to
reach a certain body weight and stay there,

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their metabolism keeps pace with calorie
consumption and they don\'t become obese.

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When food is reduced, their
metabolism apparently slows

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in an effort to conserve calories. The
same may be true for dieting humans.

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The overweight individual who\'s on
the diet doesn\'t want to starve

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and so the body makes all
of the compensations it can

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further reduce energy and protein
intake, it lowers metabolism,

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it stops the loss of making an extra skin so the
older skin sloughs often people get colder,

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they tend to drop their temperature
a little and feel colder,

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all of these are ways in which the body
says, I don\'t want to lose the energy

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that I have stored. The set point
theory may also like explain

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why nine out of ten people who tried to
lose weight by diet alone eventually end up

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back where they started. Many people
who lose weight will regain most

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or all of it and it\'s of
concern to many of us

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that losing weight and regaining
it may be hazardous. And there are

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clear evidence from studies showing
that people who lose weight

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and then regain it will have more
difficulty with him that of metabolism

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may have an increase in blood pressure.
So it\'s clearly not desirable

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to lose weight and regain. But
does the notion of a set point

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mean the fight against fat is a losing battle.
I don\'t think it can be just something

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that you say, I was dealt
this hand of genes,

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I was given this set point and therefore there\'s nothing I can do
about it. In point of fact, you can do things about yourself point,

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you can increase your exercise. First and foremost
is the active exercise itself burns calories.

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Secondly, it changes the basal
metabolic rate after exercise,

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your metabolic rate is higher so you
continue even when you\'re not exercising

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to burn fuel at a faster, less efficient
way and throw heat. Third thing it does

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exercise suppresses
appetite, that\'s good news.

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Although the biological mechanisms
that regulate set pointer unclear.

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Los Angeles endocrinologist,
Philip Kern has been examining

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a possible gene for fatness that may
explain why losing weight is so difficult.

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It involves a common body enzyme
called Lipo Protein Lipase or LPL,

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that transports fat from the
bloodstream to fat cells for storage.

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Kern found that LPL
appeared in elevated levels

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among all of his obese patients.

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But what really caught his attention was
that those who recently lost weight had even

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high levels of the enzyme.

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Now this is important because it suggests that after the
patient has lost a lot of weight, this enzyme goes up

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as if it\'s resisting the weight loss by trying harder to stuff
the fat cells so that might be another metabolic factor

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that comes into play that makes it
difficult for someone who maintain

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their weight loss after they\'ve lost it.

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LPL maybe a kind of evolutionary survival
kit that signals the body to seek and store

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fat rich foods, but there is no
reliable mechanism that protects us

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during times of feast and keeps us from
becoming obese when we flood our body with fat.

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Let\'s go back to the laboratory rats

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who maintained a constant weight when offered
unlimited rat Chow. If you change the menu

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and let them die in on what\'s called a
cafeteria diet high in fat, the same as ours,

00:19:55.000 --> 00:19:59.999
they\'re set points apparently rise
and suddenly you\'ve got a fat red.

00:20:00.000 --> 00:20:04.999
Now what is happening here is a situation
in which the food tastes good,

00:20:05.000 --> 00:20:09.999
the animal likes the food and the
animal eats to gratify pleasure.

00:20:10.000 --> 00:20:14.999
So the issue of a set
point then is if you will

00:20:15.000 --> 00:20:19.999
over ruled by the gastronomically
case, by the century, by the orgy,

00:20:20.000 --> 00:20:24.999
by the gluttony of the animal
which is not unfamiliar to us

00:20:25.000 --> 00:20:29.999
as human beings who have experienced the
same things ourselves as we are confronted

00:20:30.000 --> 00:20:34.999
with the hog and dos ice cream. Let\'s think back
to the environment that our ancestors evolved in.

00:20:35.000 --> 00:20:39.999
Remember our taste of
fats and sweets and salt

00:20:40.000 --> 00:20:44.999
is part of our heritage, we are in a sense
program to seek out those kinds of food

00:20:45.000 --> 00:20:49.999
but for most of our evolutionary
history, they were in short supply.

00:20:50.000 --> 00:20:54.999
So we evolved mechanisms that said, in
effect, when you see that food is available,

00:20:55.000 --> 00:20:59.999
grab as much as you can, the biochemical
headquarters literally for those mechanisms

00:21:00.000 --> 00:21:04.999
is the brain.

00:21:05.000 --> 00:21:09.999
Because the brain is the central
coordinator and integrator

00:21:10.000 --> 00:21:14.999
of all of our behavior. It has to know what
you\'ve eaten, and then it has to tell the body

00:21:15.000 --> 00:21:19.999
either continue eating or to stop eating.
And the basis for that decision process

00:21:20.000 --> 00:21:24.999
we think lies in the kinds of chemicals

00:21:25.000 --> 00:21:29.999
that the brain makes in
response to the food of we eat.

00:21:30.000 --> 00:21:34.999
These chemicals are the components of
the brains message transmission system.

00:21:35.000 --> 00:21:39.999
USC, nutritional biologist, Janis Fisler,

00:21:40.000 --> 00:21:44.999
believes that a biochemical malfunction
in the system maybe an underlying

00:21:45.000 --> 00:21:49.999
cause of obesity.

00:21:50.000 --> 00:21:54.999
What we\'re finding in laboratory animals is
that the brains may not be adequately sensing

00:21:55.000 --> 00:21:59.999
the nutrients that the animals are
ingesting, and therefore are not signaling

00:22:00.000 --> 00:22:04.999
and the body to expand the
energy or to wasted as heat.

00:22:05.000 --> 00:22:09.999
Likewise, the brain is not telling
the food seeking behaviors

00:22:10.000 --> 00:22:14.999
that they need to stop eating
or eat more depending on…

00:22:15.000 --> 00:22:19.999
on the status of the body.

00:22:20.000 --> 00:22:24.999
Fisler believes that some people with
these biochemical abnormalities,

00:22:25.000 --> 00:22:29.999
gain weight eating just a few
extra calories. For example,

00:22:30.000 --> 00:22:34.999
if somebody is over eats as
much as an oreo cookie a day

00:22:35.000 --> 00:22:39.999
they can gain five pounds in a
year, and yet a normal individual

00:22:40.000 --> 00:22:44.999
does not have that problem if they eat
an oreo cookie every day, their body

00:22:45.000 --> 00:22:49.999
naturally compensates for
it, or they naturally

00:22:50.000 --> 00:22:54.999
reduce the amount of food that they\'re eating
otherwise. To treat these abnormal cases,

00:22:55.000 --> 00:22:59.999
research is tinkering with the brains
chemistry said, trying to rewind

00:23:00.000 --> 00:23:04.999
what appears to be a short circuit involving
appetite control, and metabolic rate.

00:23:05.000 --> 00:23:09.999
Within the next decade, a new
generation of diet medications

00:23:10.000 --> 00:23:14.999
may finally be available to treat the causes not
just the symptoms of excessive weight gain.

00:23:15.000 --> 00:23:19.999
Already in development of thermogenic drugs

00:23:20.000 --> 00:23:24.999
designed to crank up the metabolic
fire, so more calories are burned

00:23:25.000 --> 00:23:29.999
even during periods of inactivity. Also showing
promise of powerful appetite suppressants

00:23:30.000 --> 00:23:34.999
that activate the brain chemical
serotonin to reduce food cravings.

00:23:35.000 --> 00:23:39.999
And another medication would block
fat absorption in the intestines

00:23:40.000 --> 00:23:44.999
and keep it from being stored in the body.

00:23:45.000 --> 00:23:49.999
But for the great majority of,
as according to Paul Salt man,

00:23:50.000 --> 00:23:54.999
the best way to change our biochemistry
is to change our behavior.

00:23:55.000 --> 00:23:59.999
My advice to anyone who wants to lose weight
is don\'t go for the magic, go for the real.

00:24:00.000 --> 00:24:04.999
And by that I mean understand
what causes weight gain,

00:24:05.000 --> 00:24:09.999
what causes weight loss, it\'s so
simple that it hurts the simplicity is

00:24:10.000 --> 00:24:14.999
reduced calories, increase
exercise, modify your behavior,

00:24:15.000 --> 00:24:19.999
there is no other simple way.

00:24:20.000 --> 00:24:24.999
If you\'re sitting on your
personal slice of fat city

00:24:25.000 --> 00:24:29.999
and thinking well, that\'s easy for him to
say, take heart from the story of the Pima

00:24:30.000 --> 00:24:34.999
Indians, despite having genetic and
environmental chips stacked against them

00:24:35.000 --> 00:24:39.999
they have begun to battle the
bulge by changing their behavior

00:24:40.000 --> 00:24:44.999
and borrowing from their past.

00:24:45.000 --> 00:24:49.999
For some of the solutions that Pimas
haven\'t had to look any further

00:24:50.000 --> 00:24:54.999
than their own backyard. The old ways

00:24:55.000 --> 00:24:59.999
that enabled the tribe to flourish on this
arid land may give them a new lease on life.

00:25:00.000 --> 00:25:04.999
Gradually, the Pimas are
beginning to rediscover

00:25:05.000 --> 00:25:09.999
the nutritious desert cuisine, finding
it better suited to their thrifty genes.

00:25:10.000 --> 00:25:14.999
Experts say that returning
to their traditional foods,

00:25:15.000 --> 00:25:19.999
instead of relying solely on a high fat
Western diet is not just nostalgic,

00:25:20.000 --> 00:25:24.999
but imperative to the
Pimas long term survival.

00:25:25.000 --> 00:25:29.999
There\'s a kind of irony and all of this.

00:25:30.000 --> 00:25:34.999
During the past few decades, we\'ve
finally began to understand

00:25:35.000 --> 00:25:39.999
some of these diseases of Western
civilization. And it\'s pretty clear that diet

00:25:40.000 --> 00:25:44.999
can be a major component. Foods that
in excess can be bad for our health

00:25:45.000 --> 00:25:49.999
are essentially the same food we evolved
to seek out perhaps that knowledge

00:25:50.000 --> 00:25:54.999
coupled with nutritional lessons
from our past will help us survive

00:25:55.000 --> 00:25:59.999
our future in fat city.

00:26:00.000 --> 00:26:05.000
[music]