AN AGONISING REAPPRAISAL
Body mass
Your body mass (BM) is a very important measure of your physical condition. However, it is your body mass in relation to your height that is the critical determinant – it is known as the body mass index.
Your body mass is in kilograms; use your new scales to get your new benchmark value.
Compare the mass indicated by the new scales with your old one to give you a link with any previous measurements you might have noted.
Typical clothed body mass is also of interest: indoor, and outdoor winter. You must carry the lot up the stairs, steps or hill.
Conversion
You may feel bereft that you have no fast link to your old weight measures in pounds or stones and lbs.
Pounds to kilograms: Divide by two Better: Subtract 10%.
180 pounds: 90 kg 90 – 9 = 81 kg
Stones and lbs. to kilograms: Round up – st. Multiply by 6.
8 st 7 lbs 9 st 54 kg
(One kilogram weighs 2.2046 pounds on planet Earth.)
Height
Height barefoot, in metres, is your next measurement. Get a good fix on this.
In metric, the usual way to state your height is as in: My height is one metre seventy five.
An alternative is: My height is one seventy-five.
These statements read as a height of 1.75 m.
It is not convenient to reach for the calculator every time one wants to convert to metric. An estimate in your head is often good enough to get a feel for the magnitude and it has the further advantage: it is good for the brain cells.
One way is to visualise a ladder structure with major intervals of one foot (300 mm or 30 cm) and smaller intervals of 4 inches (100 mm or 10 cm) to yield a table:
Starting point: 6 ft. 3 ins. is one-ninety.
Height / feet & ins. | Height / m | Height / feet & ins. | Height / m |
|
|---|---|---|---|---|
| 6 ft 5 | 1.95 | |||
| 6 ft 3 | 1.90 | |||
| 6 ft 1 | 1.85 | |||
| 5 ft 11 | 1.80 | |||
| 5 ft 9 | 1.75 | |||
| 5 ft 7 | 1.70 | |||
| 5 ft 5 | 1.65 | |||
| 5 ft 3 | 1.60 |
As that math expert, Mr. Family Guy, might say:
Well, it’s obvious. It’s like this:
6 and 3 are 9: Therefore, 6 ft. 3 is one-ninety.
Drop 30, you get one-sixty – that’s 5 ft 3.
Then, 5 ft 7 is one-seventy,
and 5 ft 11 is one-eighty:
One-sixty, one-seventy, one-eighty, one-ninety. Get it?
Same for 6 ft 5.
Am I right or am I right? Mr. Pewter-Schmidt?
Height-squared
Height-squared is used to calculate the Body Mass Index. It is obviously a constant for each adult individual (but not indefinitely over the years).
Height (m) | 1.50 | 1.60 | 1.70 | 1.80 | 1.90 |
|---|---|---|---|---|---|
| Height-squared (m2) | 2.25 | 2.56 | 2.89 | 3.24 | 3.61 |
Body Mass Index
The Body Mass Index (BMI) is body mass divided by height-squared. It has the units kg per m2, infrequently stated.
BMI = BM / Height-squared
Body mass (kg) | Height (m) | Height-squared (m2) | BMI (kg/m2) |
|---|---|---|---|
| 100 | 2.0 | 4.0 | 100 / 4 = 25 |
The BMI has come into widespread use over the past ten years as an indicator for health – basically, risks to health increase as BMI reaches 25 and above.
20 – 22 is ideal 25+ is overweight 30+ is clinically obese
The BMI is a general proxy for body fat: outside a range from BMI 18.5 to BMI 25, health hazards develop; that range might be described as lean-normal to fat-normal, .
The basic message is: For both women and men, fat is good; it is an essential mechanism of energy storage.
Too little is bad - you do not have enough stored energy (low fat threshold, BMI 18.5); too much is bad – you have excess stored energy (high fat threshold, BMI 25).
See the:
U.S. National Heart, Lung and Blood Institute website:
http://www.nhlbi.nih.gov/health/health-topics/topics/obe/
WHO Fact sheet on “Obesity and Overweight”:
http://www.who.int/mediacentre/factsheets/fs311/en/
For more on:
-
Body Mass Index
-
Body Fat
-
Body profile: Waist-hip ratio
-
A quick guide to the good zone
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