How to Measure Body Mass Index (BMI)

Posted by in Obesity, Researchs and Facts on February 10, 2011
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In order to decide whether someone is “thin” or “fat”, doctors usually use the Body Mass Index (BMI) as a standard. Body Mass Index is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as the weight in kilograms divided by the square of the height in metres (kg/m2).

Body Mass Index How to Measure Body Mass Index (BMI)

For example, an adult who weighs 80kg and whose height is 1.75m will have a BMI of: 80 / (1.752) = 26.12

To decide whether that number is include in underweight, normal, or overweight, let’s check this table below, which is an international classification for BMI from World Health Organization (WHO):

Classification BMI(kg/m2)
Principal cut-off points Additional cut-off points
Underweight less than 18.50 less than 18.50
Severe thinness less than 16.00 less than 16.00
Moderate thinness 16.00 – 16.99 16.00 – 16.99
Mild thinness 17.00 – 18.49 17.00 – 18.49
Normal range 18.50 – 24.99 18.50 – 22.99
23.00 – 24.99
Overweight 25.00 and above
25.00 and above
Pre-obese 25.00 – 29.99 25.00 – 27.49
27.50 – 29.99
Obese 30.00 and above 30.00 and above
Obese class I 30.00 – 34.99 30.00 – 32.49
32.50 – 34.99
Obese class II 35.00 – 39.99 35.00 – 37.49
37.50 – 39.99
Obese class III 40.00 and above 40.00 and above

BMI values are age-independent and the same for both sexes. However, the BMI table has a weakness of the inability to differentiate whether a person is overweight or just has an over-size muscle as a result of regular exercises. BMI, although not a perfect method for judging someone’s weight, is often a good way to check the obesity risk, which is quite accurate for most person.

So, how much is your BMI? Remember that being obese will put you at risk for coronary artery disease, and high blood pressure, among others. Start a diet program immediately if your BMI is near or over 30.

Diet and exercise are the safest and most natural ways to lose weight. However, there are a lot other methods that give more instant results, all with its own benefits and risks. Among those weight reduction methods are liposuction, diet pills, or lap band surgery (or gastric banding), which is one of the safest weight loss operations.

obesity fat person How to Measure Body Mass Index (BMI)