Low
Carbohydrate Diets
Carbohydrates
include sugars, starches, and fiber.
Is it
smart
to significantly reduce carbohydrates?
Low carbohydrate diets fall in
and out of fashion, and have gained a lot of attention recently, with
the added twist of the glycemic index. Like many other popular dietary
approaches to solving the weight control problem, these diets take an
extreme approach by limiting one type of food and focusing on it as the
sole source of obesity and other chronic metabolic disorders. It would
be great to have a simple solution!
To understand what a low
carbohydrate diet is, one needs a very basic understanding of the
sources of calories in the diet. There are four nutrients that provide
calories: carbohydrates, fats, proteins, and alcohol. Carbohydrates are
essential in maintaining healthy activity of the sympathetic nervous
system and in preventing ketosis, a condition that occurs when the body
must breakdown ingested fat for fuel because of a lack of carbohydrate.
Ketosis is a potentially dangerous condition that produces the breakdown
of bone, among other things.
Carbohydrates are the body’s
primary source of energy, and are quickly and easily converted to blood
glucose, the body cells’ preferred source of fuel. In particular, the
brain must have glucose as a source of energy. The brain will not use
other sources of energy except in the extreme case of starvation, in
which ketone bodies (from the breakdown of body fat) are used by the
brain. The body cannot store a large amount of carbohydrate; there is
only a short supply available as glycogen in the liver and muscle.
Therefore, carbohydrates must be supplied on a regular basis.
So, we need a certain amount of
carbohydrate to prevent ketosis, but where does it come from?
Carbohydrates include sugars, starches, and fiber. Foods that contain
mostly carbohydrate are grains, cereals, beans, fruits, and vegetables.
Sugar and flour are forms of carbohydrate, so any food made with sugar
(like soda pop) or flour (breads, pasta, bakery goods, cookies,
crackers, etc.) are sources of carbohydrate as well.
If carbohydrate is so necessary,
why would anyone want to limit it to lose
weight?
Low Carbohydrate Diets
Those who advocate severe
carbohydrate restriction point to the relationship between ingesting
carbohydrate and the insulin response. Insulin is a vital hormone that
regulates the entry of glucose to the cells, helps the body store fat,
and at high levels, is associated with damage of the arterial walls.
Carbohydrate ingestion stimulates insulin production. The problem is
that the more insulin is produced, the more resistant the cells can
become to insulin, so the blood glucose can’t enter the cells as
easily, and blood glucose and circulating insulin levels remain high,
causing damage.
The problem is that insulin
resistance is not caused by simply ingesting carbohydrates, and is not
completely solved by eliminating them. Insulin resistance has a very
strong genetic component, and is heavily influenced by level of physical
fitness and the degree of body fatness. Generally, the more fit a person
is, the less resistant to insulin, and the more body fat a person has,
the more resistant they are to insulin. So the real answer to solving
insulin resistance (and many other health problems) may be to maintain a
healthy body at a healthy weight.
Another problem with severe
restriction of carbohydrates is that it
leaves fat, protein, and alcohol
left to supply calories. Diets high in fat damage arteries and promotes
heart disease, and diets high in protein, especially animal protein, are
very hard on kidneys, causing them to work
too hard to remove the waste
products of protein metabolism.
In addition, by severely
limiting carbohydrates, you are restricted from many plant foods which
contain protective factors against cancer, heart disease and other
chronic diseases.
Certainly, it is very easy to
eat too much carbohydrate: it is in so many foods, and so available! An
excess of calories from any source (fat, protein, carbohydrate, or
alcohol) will lead to weight gain if you do not increase your activity
to match the excess food intake. For most people, the recommended amount
of carbohydrate in the diet is that at least one-half of your total
calories should be in the form of carbohydrate. Certain people, such as
those with high triglyceride levels or diabetes have special concerns
with carbohydrates and fats and should follow a diet that addresses
those needs in particular upon the advice of their physician. Choosing
carbohydrates that also provide important vitamins, minerals and other
nutrients (such as vegetables, fruits, whole grains), and limiting the
“junk” carbohydrates to special occasions will help with keeping
carbohydrate intake in proper perspective. Choosing carbohydrates that
digest more slowly or eating quickly digesting carbohydrates with other
foods is another consideration and has to do with the glycemic index,
which will be addressed as a separate topic.
Shouldn't
you seek an expert's help with your diet?
See
our sample diets - then get a diet designed to your needs!
