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Body Mass Index

Why might the body mass index be misleading in some circumstances? The Body Mass Index (BMI) is a ratio of height to body mass. The BMI is generally informative about the amount of fat a person has in their body. The typical mass of a body component such as the skeleton or all skeletal muscle increases proportionately to height. Taller people have heavier skeletons. The rate of mass increase is predictable as height increases. Individuals whose BMI exceeds the expected for their height usually have stored fat that makes up the extra mass. They are considered to be overweight or obese. However, not all humans are proportionately identical. Some people may have a more robust skeleton that has a higher mass than expected for their height. Or they may have exceptionally high muscle mass because of exercise. People who fall outside the norm in this way may be in excellent physical condition even though they are overweight based on their BMI.

View the animation below, then complete the quiz to test your knowledge of the concept.






1Body Mass Index is a method of comparing
A)age and weight.
B)age and height.
C)muscle mass and weight.
D)height and weight.



2A person with a BMI of 20 would be considered
A)underweight.
B)normal range weight.
C)overweight.
D)obese.



3In August 2001, when Mark McGwire broke the home run record in baseball, his BMI classification was
A)underweight.
B)normal range weight.
C)overweight.
D)obese.



4BMI is often used as a screening test because it is
A)very accurate in determining obesity.
B)inexpensive and quick.
C)the best way to tell if you are morbidly obese.
D)the best way to determine muscle growth.



5A person with a BMI of 12 would be considered
A)underweight.
B)normal range weight.
C)overweight.
D)obese.







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