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tissue, BMI often overestimates body fat in muscle builders and other ath-
letes. This is what has happened to Andrew in our example. In fact, accord-
ing to BMI alone, Arnold Schwarzenegger, Sylvester Stallone, and Jean-
Claude Van Damme are all “obese.” On the other hand, the index can
underestimate body fat in the elderly and others who have lost muscle mass.
Lastly, BMI offers no means of measuring heart-healthiness such as blood
pressure or cholesterol levels. BMI is merely one tool most effectively applied
in conjunction with other diagnostic measurements.
Despite its limitations, BMI is the most commonly used method for
determining if someone is overweight or obese. It is the measurement of
choice for many health professionals. The NIH, the CDC, the National Heart,
Lung and Blood Institute (NHLBI), the NIDDK, and the World Health
Organization all concur that a BMI of 25 to 29.9 defines overweight, and a
BMI over 30 indicates obesity. Although not a direct measure of percentage
of body fat, BMI is a more accurate indicator of the
character of body mass than weight alone.
What’s the
Problem?
So why should we care if American adults and teens
are getting fatter? Why should we concern ourselves
with things like overweight or obesity? The answer is
simple: The health risks of overweight and obesity are too serious to ignore.
Excess fat impairs the function of many body systems and organs, leading to
multiple health issues and even death. Two-thirds of us will face those issues
down the road, and if we don’t, we definitely know someone who will. But
how can we know how much risk we face?
Doctors can predict likely health problems based on the degree of being
overweight and the location of fatty deposits in a person’s body. For exam-
ple, a person whose fat is located primarily in the abdominal region is at
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