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Weighing In: Defining the Problem / 17
Once you have your result, compare it to this chart to determine whether
your amount of body fat falls into a healthy range.
BMI
CLASSIFICATION
< 18.5
= Underweight
18.5–24.9
= Normal
25.0–29.9
= Overweight
30.0 and above
= Obese
(Source: U.S. Centers for Disease Control and Prevention [CDC])
Here is a sample formula for a person who is five feet, three inches tall (63
inches) and weighs 120 pounds (notice we are using the U.S. rather than the
metric formula):
[120 ÷ (63 x 63)] x 704.5 = BMI
[120 ÷ (3969)] x 704.5 = BMI
[.03] x 704.5 = 21.14
The person in our example has a BMI of 21 and thus falls within the normal
range.
Keep in mind that BMI ranges are simply practical
guides
for defining
overweight and obesity. They are not rigid cutoff points. In fact, overweight
and obesity classifications have proven difficult to pin down. The World
Health Organization (WHO) describes obesity as “abnormal or excessive fat
accumulation that may impair health,” but the exact point at which such
impairment occurs is not precise and differs from person to person. The
CDC states: “Simple, health-oriented definitions of overweight and obesity
should be based on the amount of excess body fat at which health risks to
individuals begin to increase. No such definitions currently exist.”
Because precise definitions for overweight and obesity are elusive and