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Nutrition
Nutrition is the most important need of the body. As such, it makes
sense that eating is important because that's how we get the nutrition we
need. Of all the nutritional needs, energy is the most important. Without
energy you can't move, can't think, and can’t stay alive. Because of this, the
body has elaborate ways to convert energy from foods to usable energy and
to stored energy (just in case there's no food at some point in the future),
and in particular, to body fat. This ability to store energy and conserve
energy is so vital, and our predecessors passed it on, and did it so well that
today, we have a population of very efficient energy storers and conservers;
Now doesn’t that sound better than fat people. Millenniums ago this trait
was a lifesaver, however, today this trait causes disease and even death,
certainly it causes us to become overweight and obese.
Energy Producing Nutrients
There are three energy-producing nutrients: carbohydrates, proteins,
and fats and one source of energy that is not a nutrient: alcohol. They each
provide energy in a different way and in different amounts. For example,
carbohydrates provide 4 calories per gram and fat provides 9 calories per
gram. Taking this a step further, this means a pound of dietary fat (butter)
has 4000 calories, but a pound of pure carbohydrate (sugar) only has 1800.
Fats are 2¼ times more concentrated so that even before there is any
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explanation on how the energy nutrients are used it becomes obvious that
FATS are the most Fattening of the energy nutrients!
And though total calories may be your first concern, they shouldn't be
your only concern.
How your body uses the various energy producing
nutrients is equally, if not more, important.
Carbohydrates provide your
body with an immediate source of energy called blood sugar (glucose).
Your
brain cannot function without blood sugar. If totally deprived, you would
feel dizzy, faint, go into a coma and eventually die. When your body realizes
you haven't eaten, and it's getting dangerously low on blood sugar (and your
small reserve called liver glycogen), it uses the stress hormones to help make
more. This causes you to be irritable, shaky, and nervous.... Not a pleasant
condition.
The brain is not the only part of your body that needs blood sugar to
survive. Blood sugar is the preferred fuel used by every cell in the body for
a your metabolism. Think of your metabolism as the energy you need each
day "just to stay alive". You need energy to keep cells alive, repair tissue,
produce heat to maintain your body temperature, balance electrolytes on
different sides of a cell, make digestive enzymes, create hormones, etc. This
"staying alive" business uses about two-thirds of the total amount of energy
you need each day.... and this is without moving a muscle.
So, if your
metabolism is running slower, you are less likely to burn as many of the
calories you eat and much more likely to store them (as fat).
Another way your body can use blood sugar is in your muscles. When
you do quick, short-duration movements i.e., getting up from your chair,
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scratching your nose, getting something out of the cabinet, walking to your
car, or even more intense things like doing a few pushups, or lifting some
thing extremely heavy like your briefcase/purse, your muscles prefer to use
sugar because it's readily available. Even during activity of longer duration,
i.e., walking or biking, when your body is able to use fat, you still need sugar
to start and then maintain that exercise.
If carbohydrates provide you with all this needed energy for brain
function, metabolism, and muscles, why have they received such bad press?
Well, here's the bad new and the worse news.
If you eat more
carbohydrates than your body can use at the time, it simply stores them
as (here's the bad news) body fat. And once stored as body fat (here's
the worse news) it can never be turned into sugar again. This explains why
if you overeat one day that you'll still get hungry the next.
Foods laden
with simple sugar (candy, cakes, pies, etc) are the real culprits. These foods
with a lot of calories are absorbed quickly and there's little time for your
body to use them. Complex carbohydrates; fruits, vegetables, beans, rice,
grains, etc. may have fewer calories, which are absorbed more slowly and
therefore available longer. Unless eaten in huge quantities, these foods are
much less likely to be stored as body fat.
Your body has a limited store of carbohydrates called glycogen. A
normal size male may have around 1400 calories worth and a female about
1200 calories. The problem is that 80% of this reserve is in muscles and
only 20% in the liver. The muscle reserve is only used for muscles when they
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are physically active. This is important during exercise and helps explain
why exercise helps keep a person from getting fat. If this carbohydrate
reserve is depleted, then when carbohydrates are eaten they have a place to
go without the necessity of turning them to body fat. The liver reserve is
what becomes available to regulate blood sugar when a person hasn’t eaten a
dietary carbohydrate for a while and needs this fuel for energy. Because so
little carbohydrate is stored in the liver it is possible to depleted this in
just a few hours.
Since blood sugar is so important, what happens when you haven't
eaten and there aren't any carbohydrates from the diet or in the liver to
produce blood sugar?
This is one-way protein fits into the picture. First, protein is essential
because it is the only dietary nutrient that makes body protein i.e., muscle,
skin, enzymes, red blood cells, hair, hormones, etc all the things that keep
you alive. Since protein is so critical to life, your body does everything it can
to protect and conserve it.
Because your body is so good at conserving
protein, (by reusing the building blocks of proteins called amino acids), it
needs only a small amount each day from the diet. A maximum of 60 grams
for a female and 80 grams for a male is the recommended amount of protein
per day. This equates to no more than 6-8 ounces of animal protein per day.
Since complex carbohydrates also provide protein, you can eat even less
animal protein and still get all you need. If you eat more protein than you
need, the excess will be stored as fat and once again is never again
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available for use as body protein. In a nutshell, you can't turn fat into
muscle.
Protein, however, is your salvation when you haven't eaten.
Rather
than die, your body can turn protein into blood sugar, if none is otherwise
available (i.e. when you skipped breakfast). During this scenario, the only
protein available is your own body protein, so you actually burn part of your
own tissue to fuel your brain and your metabolism when you don't eat. It
seems obvious that you couldn't do this for long periods of time without
wasting away.
To prevent this from happening, your body slows your
metabolism and learns to live on less fuel. This is called metabolic
hibernation. The more you deprive your body of energy, the slower your
metabolism gets. With a slower metabolism, foods that you do eat are less
likely to be used and more likely to be stored as fat. This is why when you
go on a "diet" to lose weight, you may lose a substantial amount of the
weight as muscle, but when the diet is stopped you gain it back as fat.
The last energy-producing nutrient is dietary fat. The purpose of fat
is to provide a lot of concentrated energy for storage. When we lived in a
society that demanded a great deal of physical activity each day, fat
provided those calories. Fortunately or unfortunately, in the last century
the amount of fuel needed for physical work has drastically decreased. In
addition, because a large variety of foods are always available in the United
States, extra body fat is no longer necessary for survival.
A sensible way to reduce fat storage is to eat less dietary fat. Nearly
all (97%) of dietary fat must be stored as body fat before you can use it.
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So when you eat that pat of butter, it will end up on your hips, thighs, or
abdomen before you can use it. And here’s the real kicker, once you have
deposited fat on your body, the only part of your body that can use it is your
muscle. If you’re not physically active each day, there’s no way your muscles
can use the amount of fat you’ve stored.....so you get fatter and fatter. If
you’re saying, “But, I’m physically active each day, chasing after kids, or
running an office,” your idea of being physically active doesn’t come close to
the degree of movement necessary to burn substantial amounts of fat and
change your body to use more fat in the future. Therefore, you probably
need to add some “formal” exercise to your weekly routine.
Since your muscles are the only part of your body that can use fat as a
fuel and they will only use fat as a fuel in the presence of oxygen; “aerobic”
or “cardiovascular” exercise will use body fat most effectively. The term
aerobic simply means with oxygen and includes all continuous, long duration
types of exercise including activities like walking, biking, swimming, aerobic
dance, etc. (See exercise section for more information).
Note that once any of the energy containing dietary nutrients;
carbohydrate, protein or fat, becomes body fat that the only place it can go
is to muscle and the only time the body will use a lot of fat is therefore
when we use our muscles, i.e. we exercise.
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FOOD/ ENERGY DYNAMICS
DIETARY
BODY FUEL
carbohydrat e
prot ein
body
prot eins
fat
all
USED FOR
blood sugar
brain
met abolism
body
fat
Long Term
muscle
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Non-Energy Producing Nutrients
Three nutrient categories are essential for a healthy body but do not
provide energy. They are vitamins, minerals and water.
Vitamins and minerals are the most misunderstood of all the nutrients.
Their job is to release energy from food, assist in nerve and muscle
reactions, help heal wounds, maintain healthy bones, teeth, hair and skin, and
are a part of all cell membranes, hormones, etc. Obviously, certain amounts
of each vitamin and mineral are essential for good health and well-being.
We know that if you don’t get enough of each of the vitamins/minerals
you can develop symptoms of malnutrition. These symptoms disappear when
the missing nutrient is supplied.
Often it is assumed that if a little vitamin
supplementation is good, a lot is even better. Not only is there no sound
scientific proof this is true; some vitamins and minerals may be harmful in
large quantities. Because of this misconception and the widespread practice
of taking vitamins and minerals in pill form, the American Dietetic
Association, American Society of Clinical Nutrition, American Institute of
Nutrition, and the National Council Against Health Fraud have issued a joint
statement warning Americans about unnecessary and sometimes unsafe use.
Think about it this way, a 1000 mg supplement of Vitamin C each day is the
equivalent of eating 20 oranges. Do you really think that you need to eat 20
oranges each day just to stay healthy?
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The best way to make sure you’re getting enough vitamins and
minerals is to eat a variety of foods each day, focusing on the
carbohydrates; fruits, grains, and vegetables. If you’re still concerned,
a low dose multivitamin/mineral supplement may be taken.
Water, the most abundant substance in your body, accounts for
50-60% of your weight. Water is essential for proper functioning of
all body cells, for transportation of nutrients throughout the body, the
excretion of waste products, regulation of body temperature, and
lubrication of the joints. As a matter of fact, scientists estimate that
you could lose all stored glycogen (carbohydrate), most reserve fat,
and almost half your muscle and still survive. However, water loss of
just 10% is serious and loss of 20-22% can be fatal.
The daily intake of fluid should be six to eight glasses. All fluids
count toward this requirement.
Some foods, especially fruits and
vegetables also supply water. Because water has weight, you will lose
weight if you lose water, but losing water weight does not affect on
how fat you are.