Explain BMI as an important indicator of physical growth with an example
Answers
Answer:
What Is BMI?
BMI (body mass index) is a calculated number representing a person's level of fat or obesity level. According to the Centers for Disease Control and Prevention (CDC), a BMI of 30 or above indicates obesity. BMI levels are broken down by weight range and are as follows:
BMI < 18.5 is underweight
BMI 18.5-24.9 is normal weight
BMI 25-29.9 is overweight
BMI 30-39.9 indicates obesity
BMI > 40 indicates morbid obesity
In children, age and gender are considered in tables that are produced for growth charts by the CDC. However, BMI is calculated with the same formula for both children and adults. In general, children are assessed as being underweight if they fall below the 5th percentile and overweight/obese if they fall above the 95th percentile.
Calculating BMI: The Formula
The formula to calculate BMI requires information about a person's height in meters and weight in kilograms. For weight in pounds and height in inches, there is a different formula, but due to rounding, it may not produce the exact same results. The BMI formulas are:
BMI = weight (in kilograms) / height (in meters) ^2
or
BMI = weight (in pounds) / height (in inches) ^2 * 703
Calculating BMI: Special Considerations
There are some concerns related to BMI that mostly have to do with the fact that fat and lean muscle tissue are not considered in the formula. For example, a man who is an athlete may have a higher BMI calculation than a man who never leaves his desk at the office and is overweight. Of course, you would not say that the athlete is overweight - but he is muscle bound, and muscle weighs more than fat.
Another situation that may cause a misleading BMI is the calculation for a tall and lean person. The extra height of the individual comes with extra weight. This might skew the BMI and make it appear high even if the person is relatively lean. Also, as a person ages they may lose height, so the BMI may be increased without any significant change in the person's weight.
Example BMI Calculations
If you have your weight in pounds, as most of us in the U.S. do, you'll need to convert the weight to kilograms first. The formula to convert pounds to kilograms is dividing the weight in pounds by 2.2. To convert inches to meters, you take the height in inches and multiply it by 0.0254.
Let's do a calculation. A man weighs 220 pounds and is 70 inches tall. We will perform the BMI calculation using both ways to show how to use the formulas.
English Units
BMI = weight (in pounds) / height (in inches) ^2 * 703
(220 / 70^2) * 703
(220 / 4900) * 703
0.045 * 703
BMI = 31.63
Metric Units
BMI = weight (in kilograms) / height (in meters) ^2
220 lbs / 2.2 = 100 kg
70 in * 0.0254 = 1.78 m
100 / 1.78^2
100 / 3.17
BMI = 31.55