The Evil of Carbohydrates?

(May be reprinted freely if linked to
www.ExerciseCertification.com)

In recent years, carbohydrates have been labeled as the
nutrition ‘bad guy’ because of the increases in insulin that
occurs during metabolic processes. The secretion of insulin is
dependent primarily upon the concentration of blood glucose – an
increase of blood sugar brings about an increase in the
secretion of insulin. Therefore, one function of insulin is to
lower glucose.

Conversely, the body increases blood glucose levels by secreting
another hormone called glucagon. If blood glucose levels remain
high, and that energy source is not burned shortly after it is
consumed, the excess glucose is shuttled off to the muscles for
storage. If the muscles have reached their limit in storage
capacity, and the body does not require extra glucose to sustain
body activities, the excess converts to fat.

Also, as insulin efficiently clears the blood of excess sugar,
blood sugar levels oftentimes dip below normal and will produce
the infamous ‘sugar blues’ or a ‘downer’, followed by a possible
craving for more sugar consumption. Lastly, while insulin levels
are high or active, the body will not burn fat as energy since
the body is attempting to utilize as much blood sugar as
possible. (Note that fat is not used as a primary energy source
while eating an energy-sufficient, healthy diet and fat is used
more heavily only during periods of fasting and extensive
aerobic-type exercise.) Hence, ‘high-fat-low-carb’ advocates
claim that we should not want:

1) Excess carbs to turn into fat (what do they think happens to
excess fat and protein kcal?);

2) To feel groggy with low energy from the insulin ups and downs
associated with high carbohydrate (sugar) consumption; and

3) High carbs in the diet since they prevent us from burning
body fat. Although these factors are true, the extent or
magnitude of their validity varies in accordance to a number of
conditions, such as:

i) How active is the individual?

ii) How many kcal is the individual ingesting (including carbs)
per meal?

iii) What comprises an individual’s food and carbohydrate intake?

HOW ACTIVE ARE YOU?

The more active a person, the more carbohydrate he or she should
consume. Also, the greater the physical activity, the less
insulin the body produces since muscles become insulin sensitive
after exercise and glucose tolerance improves as a result. The
Food Guide/Pyramid recommends about 50% of kcal in the average
individual’s diet to be in the form of carbohydrate. Therefore,
if a person is very active, the amount should be increased to
about 60% since nearly every activity uses a great deal of blood
glucose and muscle glycogen for energy, but only a smaller
percentage of fat. In fact, athletes who consume a high-carb
diet (60%) can maintain higher-intensity exercise longer than
those following a low-carb diet (<40%). If a person is
relatively sedentary, then much less energy is required, and
30-40% will suffice.

The bloodstream holds about only a one-hour supply of glucose
and muscles store about only a half-day’s energy needs. The
‘sugar’ requirements of the nervous system (including the brain,
an organ that survives on nothing but sugar) for the average
adult is approximately 100-150 g per day (and 100 g minimum to
prevent ketosis, or 600 kcal). If a 90 kg/200 pound, moderately
active man consumes 3,500 kcalories per day, this is equal to
17% of his total caloric intake… just for his nervous system.
This does not take into account the remainder of his
requirements, the energy required for metabolism of food, or his
general activity levels such as work, sports, weight training,
reading, housework, walking, etc.

Since this man is moderately active, about 55% of his kcal
should be in the form of carbohydrate, or 1,925 kcal, or 481
grams. If he were very active, the percent should probably be
closer to 60%. That leaves 20% for fat intake, and 25% for
protein intake.

HOW MANY KCAL ARE YOU CONSUMING?

Although national surveys indicate that we are eating less fat
now than 20 years ago, we are also eating more kcal.
Consequently, a reduction in fat and an increase in
carbohydrates are hardly the problem. Rather, it is the total
number of kcal consumed that is of vital importance in fat gain.
If total caloric intake is below maintenance levels, a person
will reduce fat, even if 80% are in the form of carbohydrates.
(In fact, Southeast Asian diets are 80-90% carbohydrate, yet
these individuals, on average, are not considered overweight but
underweight. Conversely, an Inuit [Eskimo] diet is only about
15% carbohydrate intake and most are overweight because of the
high fat/calorie intake.)

In regard to energy levels, one ‘pro-fat advocate’ recollected
the days when he trained for 2+ hours per day, while he consumed
about 6000 kcal per day, and yet felt tired all the time. At
under 200 lbs bodyweight, this person never considered in
general how such a large quantity of food caused his insulin
levels to go awry. He further attributed his depression and
chronic fatigue to his state of hypoglycemia, but the American
Diabetic Association has repeatedly stated that there is no
evidence in connection to these symptoms, including nervous
breakdowns, juvenile delinquency, and childhood behavior
problems. Moreover, what most people experience after a meal is
a change in blood plasma glucose concentrations and not actual
hypoglycemia, which is a serious medical condition that requires
medical treatment.

WHAT TYPES OF CARBS DO YOU CONSUME? The next factor to consider
is the composition of meals and dietary carbohydrate
consumption. Obviously simple sugars/empty kcal that consist of
concentrated sweets and that come from low nutrient (junk) foods
should be limited or eaten infrequently. By reducing the
concentrated and simple sugars in the diet, this change could
contribute to a reduction in the risk of obesity, Type II
diabetes, cancer, cardiovascular disease, and tooth decay. But
it is not so simple as to suggest that simple sugars create the
greatest insulin spike since the effect of food on blood glucose
depends on several factors that constitute a meal’s total
glycemic index.

First, the ratio and types of foods must be considered. Fat
helps to slow digestion and absorption processes, thereby
resulting in a lower and a less steep insulin spike. Hence, a
food with a high glycemic index (e.g., potato) can have little
effect on rising blood sugar levels if it is eaten with a high
fat food (e.g., steak). Fiber tends to have an effect in keeping
blood glucose levels down, and eating sucrose with whole wheat
bread will not cause problems even for a diabetic. In fact,
diabetics can consume up to 50% carb intake, so long as most are
low on the glycemic index to keep blood glucose response to a
minimum.

Refined starches (white flour and rice, cornstarch, pasta,
enriched breads, and breakfast cereals) digest and absorb a
little slower than simple sugars, but these foods still should
be limited within the diet. Complex starchy carbohydrates, such
as sweet potatoes, winter squash, yams, unrefined grains and
grain products (e.g., barley, brown rice, buckwheat, oatmeal,
and whole wheat products) are the preferred source of energy
since they are high in fiber and digest the slowest. Slow
digestion means slow glucose conversion, energy which
burns/oxidizes during body functions at about the same rate at
which it is produced.

Further, the process of digesting carbohydrates as a whole burns
more kcal than the digestion of an equivalent amount of fat.
However, even refined and whole grain starches break down to
produce glucose, with the excess storing as fat tissue.
Nonetheless, it is over-consumption of whole grains that results
in added fat, a situation which is no different than
over-consumption of healthy essential fatty acids or proteins.
Hence, it is not carbohydrates that cause problems of excess fat
gain, but the choice and amount of carbohydrate.

The form of the food also alters the glycemic response because
of the time it takes for the food to be digested and absorbed:

Liquid – quickly digested and absorbed.

Dry – opposite to the liquid state, resulting in a slower rate
of digestion and absorption.

Finely Ground – digests and absorbs better than dry because of a
larger surface area, and this causes food to break down better
and faster.

Raw – more difficult to digest than cooked foods; usually harder
and tougher and requires more time to be broken down, digested,
and absorbed.

Cooked – breaks down, digests, and absorbs faster than its raw
counterpart.

OTHER REASONS FOR HIGH (SUFFICIENT) CARB INTAKE

A most important complimentary aspect of carbohydrate is its
protein-sparing effect. When the body is low in energy or when
it is deprived of sufficient kcal, it will use its glucose
stores. Once depleted, the body uses protein to manufacture
glucose. Consuming sufficient carbohydrates guarantees that
minimal protein in the muscles will be catabolized for energy
requirements. Conversely, low carb diets accelerate protein
catabolism to produce energy by more than 100% than with a
moderate to high carbohydrate diet (50-60%).

High-fat advocates further suggest that if carbohydrates in the
diet are limited, the body will use fat for energy. Although fat
can supply most of the body’s tissues with energy, if need be,
it cannot supply energy for the brain, which requires glucose.
Even during fasting, fat is used last as an energy source.
Neither can fat optimally supply the body with energy required
for intense weight training, the main fuel source required from
carbohydrates. Even with aerobic exercise, muscles cannot
function effectively on fat alone, but will utilize glucose
simultaneously. Moreover, as the body hurriedly breaks down fat
for energy on a low carb diet, the process is often incomplete
and produces by-products that the body must eliminate.

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