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BMI (Body mass index) is used to measure our body fat.


Body mass index is also called Quetlet Index. It is a measurement technique by which we can measure our body fat based on our height and weight. It is world widely.

How to determine our BMI

We can estimate BMI by following way.

BMI= weight (kg)/height (m2).


Let my height is 5 ft 4’’, and my weight is 57 kg. Now I am going to calculate my BMI.

[1ft= 12 inch, so 5ft 4inch ={(12*5) +4} = 64 inch. 1 inch = 2.5 cm so, 64 inch =(64*2.5) =2.56]

So, my BMI is =weight (kg)/height (m2) =57/1.60*1.60= 22.2


WHO referred that if one’s BMI is 18.5 then he or she will suffer from  underweight, malnutrition, and whose BMI is greater than 25 he or she will suffer from overweight and when BMI comes above 30 then he or she will suffer from obesity.

Categories BMI range kg/m2 BMI prime
Very severely underweight Less than 15 Less that 0.60
Severely underweight from 15 to 16 from 0.60 to 0.65
 Underweight  from 16 to 18.5 From 0.65 to 0.75
Normal (healthy) from 18.5 to 25 From 0.75 to 1
Overweight from  25 to 30 From 1.0 to 2
Obese class 1(moderate obese) from 30 to 25 From 1.2 to 1.4
Obese class 2 (severe obese) from  35 to 40 From 1.4 to 1.5

BMI for age

To assess body fat of any children, BMI is used.  It is calculated same way as for adults. When people whose age 20years or under having BMI is less than 6th percentile then he or she considered as underweight and above 94th percentile will suffer from obesity. When BMI is 86th to 96th for the age group of under 20 will suffer from overweight.

Things that you should know about BMI


  • It is a simple method
  • Time consuming method
  • Easy to understand
  • Apart from shoe no need to remove cloths.

Short comings

  • It is not distinguish between overweight and obesity.
  • It is not differentiate between muscle mass, fat, internal organ. Skeletal weight.


BMI provides us a quick result about people’s body fat. It has some limitations. To get an accurate result we should use BMI with other anthropometric test.

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