Dear All,
When you have been weighed in your doctor's surgery, it might be politic to
ask the doctor, or the nurse, would they mind calculating your Body Mass
Index (BMI) as you want to know if you are in the correct BMI range.
As you know, this is relatively easy to do in metric (see below) and quite
difficult using old measures.
At the very least, it might get the surgery staff thinking on another level.
Body Mass Index (BMI)
Your Body Mass Index (BMI) is a quick method to see how your height and mass
compare to the rest of the population. Body mass index (BMI) has become the
medical standard used to define normal body mass and obesity. Calculation of
your BMI can give you an estimate to determine if you may be at health risk
due to excessive weight.
Your BMI is defined as your mass (in kilograms) divided by your height (in
metres) squared.
The calculation is fairly easy � you divide your mass in kilograms by the
square of your height in metres. This is an example for a friend of mine.
I laid it out like this.
His mass is 94 kilograms.
His height is 1.8 metres
His height squared is 1.8 m X 1.8 m = 3.24 m2
The formula for Body Mass Index is:
BMI = (mass in kilograms) � (height in metres)2
For my friend this is:
BMI = 94 kg � 3.24 m2 = 29.01234
So his BMI is 29 (rounded)
So what does this BMI mean?
In 1997 the United Nations World Health Organization (WHO) discussed an
escalating epidemic of overweight and obesity affecting many countries in
the world. As part of their action they defined various levels of Body Mass
Index (BMI). WHO were concerned that people with a high BMI are more likely
to develop non-communicable diseases and other health disorders.
WHO has agreed on an international standard for measuring overweight and
obesity. For assessing obesity in adult populations, the BMI categories are:
BMI below 18.9 means underweight
BMI between 19 and 24.9 means normal.
BMI between 25.0 and 29.9 means overweight.
BMI of 30 or more means obese and there are various grades of obese.
Class I obese: BMI from 30 to 34.9
Class II obese: BMI from 35 to 39.9
Class III obese: BMI is above 40
These BMI figures are a useful guide to the relationship between your body
mass, your height and your health, but only you can know what they mean for
you.
Clearly my friend will have to consider ways he might reduce his BMI from 29
to somewhere below 25. These calculations work well for obese people, but
they are not so useful for evaluating fitness.
As usual, there is still debate about general conclusions that may be drawn
from BMI numbers. As an example of this debate, I quote from the letters
section of the Melbourne newspaper, 'The Age'.
**
'Obesity is defined as having a body mass index (BMI) of 30 or more, while
those in the range 25-30 are considered overweight. The BMI is calculated by
dividing a person's weight in kilograms, by the square of their height in
metres.
'The problem is that this does not take into account one's width, as
distinct from girth, or whether the weight is made up from fat or muscle.
Thus, by this criterion, about 30 per cent of all Australian Football league
players are overweight. For example Adelaide's Andrew McLeod has a BMI of
26.6 and Carlton's Anthony Koutoufides, 26.9. These would be considered to
be two of the fittest players going around'.
**
However, having said all of this, there is an easier way for you to decide
if you are overweight or not. Simply follow these steps:
1 Find your height in metres. For example say you are 1.72 metres tall.
2 Remove the 1 and the decimal marker, to leave the number 72.
3 Your ideal body mass is 72 kilograms.
4 If you are more than 20�% higher than this you are obese. In this
example you would have to have a body mass more than 86�kilograms to be
Class 1 obese. Class 11 obese would be 100 kilograms, and Class 111 obese
would be 114�kilograms.
Note for the historians
Body Mass Index is also known as the 'Quetelet Index' named for Jacques
Quetelet, an early 19th century statistician who applied statistical methods
to anthropometric data to establish his 'Quetelet Index'.
Cheers,
Pat Naughtin LCAMS*
Geelong, Australia
Pat Naughtin is the editor of the free online newsletter, 'Metrication
matters'. You can subscribe by sending an email containing the words
subscribe Metrication matters to [EMAIL PROTECTED] Pat is recognised
by the United States Metric Association as a Lifetime Advanced Certified
Metrication Specialist (LCAMS).
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