|
In
sports medicine we are often concerned about the optimum body
composition for different people.
Gymnasts should have drastically different proportions of
muscle, fat and bone than football linebackers.
Furthermore, we are interested in what is healthy for
fitness enthusiasts, weekend warriors and non-athletes as well.
Many
people determine their body composition status by body weight
alone. While this
is indeed an important parameter, it is by no means a complete
way to determine whether or not you have the correct body
composition. Consider
the examples of a 300 pound football linebacker with 15% body
fat and the 5’2’’ small framed woman who has 35% body fat.
Over
the years, several methods of determining body fat percentages
have evolved. These
range from the very simple to the extremely exotic.
For the most part, there are three practical and accepted
methods of determining body fat.
The
first is probably the least used and most complicated.
Its called hydrostatic weighing.
This method is based on the principle that fat is less
dense than water and will tend to float.
Bone and muscle are both more dense than water and will
sink. In order to
determine the percentage of body fat, an examiner must know the
patient’s weight in air and their weight in water. Then, using a simple mathematic formula, it is possible to
determine the percentage of body weight that is fat.
A
second method that is becoming both more practical and more
popular recently is bioimpedance.
This technique makes use of the observation that body
tissue that does not contain fat conducts electricity much
faster than fatty tissue. Early
bioimpedance techniques involved inserting needles into the
muscle tissue. Needless
to say, this wasn’t particularly popular.
However, today’s methods use skin electrodes and is
completely painless.
Companies
from Sharper Image to Walmart are now offering fairly low cost
devices that will measure bioimpedance.
Although this quick and repeatable method of measuring
body fat is very attractive, there is evidence to suggest that
it may be one of the least accurate and precise methods of
measurement. The
data may be affected by several factors including hydration
status and young lean males may have their body fat percentage over predicted.
The
most tried and true method of measuring body fat is called
anthropometry or skin fold measurement.
This uses the measurement of folds of skin to estimate
total body fat composition.
It requires a trained examiner to take one or more skin
fold measurements (depending on the method) and the use of a
table to estimate body fat.
This method is both accurate and repeatable when
performed by a skilled examiner.
Many
organizations have published recommendations regarding the
optimum percentages of body fat for different people.
For example, the American College of Sports Medicine has
said that 16%-18% is acceptable for men of all ages and 22%-26%
for women.
Various
studies have looked at ideal composition for specific sports or
specific positions. However,
like the measurements for lay people, there is not general
agreement in this area.
Aside
from being aware of their body composition, people often would
like to change it. It
is rare to find someone who is satisfied with their body and
wouldn’t like to change their percentage of muscle or fat or
at least redistribute their proportions.
One could argue whether this national obsession is
healthy or not but it is well established that the trend exists.
For
athletes trying to gain weight it is important (for the most
part) that they try to gain muscle rather than fat.
This is done with a combination of increasing their
caloric intake and using strength training exercises to increase
their lean mass.
Weight
loss (a more common goal) should be viewed in the context of
body composition as well. It
is unhealthy to lose lean mass in order to drop total body
weight. As with
weight gain, exercise is an important factor as well. Exercise for weight loss should emphasize not only lean mass
expansion but fat loss too.
With
either weight loss or weight gain, a healthy diet is key.
It
should be mentioned that in today’s aesthetics driven society,
eating disorders are becoming ever more common.
People with eating disorders have complex problems that
go beyond the scope of this article.
However, it should be said that if you believe that you
or someone you know has an eating disorder, it is vitally
important that professional help is sought. These problems are extremely unhealthy and may require
aggressive treatment.
|
