Body Mass Index
Body Mass Index is a method made to measure the ratio of body fat by using person’s height and weight statistically. Its not the accurate measure of body fat just an estimated one.
History: Invented by Belgian Polymath Adolphe Quetelet between 1830 and 1850. Body Mass Index is obtained by dividing a person’s weight to the square of its height in metric scale this formulae us height in metric scale. This formulae is used universally and it’s answer comes in unit measure of kg/m2.
In SJ Units – BMI = Mass (Kg) / Height2 (m2)
In Imperial Units – BMI = mass (lb) x 703 / height2 (in2)
Categories of BMI: According to universally developed BMI charts, the values of different body fats are as follow.
<18.5 is considered underweight
18.5 – 24.9 is considered Normal Weight
25 – 29.9 is considered Over Weight
30 or more is Obesity for sure.
Over 40 is Morbidly Obese.
Ideal BMI for Women
Regardless of the fashion trends and how you appear physically, what’s important physiologically in the BMI. If you are having values between 20-22, it’s good enough. Don’t follow any strict diet charts. Be happy as you are having acceptable appearance and best BMI value.
Ideal BMI for Men
BMI of 23 and 25 is considered ideal for men.
You can also calculate your Body Mass Index by using BMI chart where a horizontal axis displays weight and vertical axis displays height using Contour lines for BMI values or BMI categories are differentiated by using colours.
Popularity of BMI
In 1972 Ancel Key’s paper proved that BMI is the best method used to measure the body fat by using height and weight. He used it for population studies and individual analysis widely. It is simply a method to calculate any person’s fatness or thinness.
Therefore, physicians used this method worldwide dealing with Over and Underweight patients. Although its actual purpose was to simply classify the lethargic or sedentary people with normal body mass proportions.
BMI is directly proportional to weight for a given height, but inversely proportional to a given weight to the square of the height.
BMI system is further modified to BMI Prime. It is the ratio of your actual BMI to the upper limit BMI which is 25 for Western countries. BMI Prime is a number without dimensions and International units.
According to BMI Prime
<0.74 are underweight
0.74 and 0.99 are Normal
1.00 and above are Overweight
For Asian countries the upper limit of BMI is 23 rather than 25.
Advantages of BMI System
It’s a very easy way to calculate how much a person is over or underweight by comparing his values with others of the same height. But the important thing to remember is that the body built is also responsible for the value. A person might be muscular rather than fatty so before losing weight must consult your physician first. BMI categories are not a tool to predict health status; there validity is limited to statistics only for adults.