What Is Body Mass Index (BMI)?

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Body mass index is a ratio of weight to height squared.

The index correlates reasonably well with body fatness and health risks. It can, therefore, be useful when assessing nutritional status, underweight, overweight and obesity.

What Is Body Mass Index (BMI)?


Body Mass Index

Calculation of BMI:

BMI = Weight (kg) / Height (m)2

BMI = Weight (lb) /Height (in)2   x    704.5

Thomas is 90 kg and 1,84 m           BMI = 90/(1,.84 x 1.84) = 26.6 kg/m2
Helen is 180 lb and 65 in                 BMI = 180/(65 x 65)  x 704.5 = 30.0 kg/m2

Here you can easily calculate your body mass index if you know your height and weight.

  • Underweight: BMI < 18.5 kg/m2
  • Normal weight: BMI 18.5 – 25 kg/m2
  • Overweight: BMI 25 – 30 kg/m2
  • Obese: BMI > 30 kg/m2

Research indicates that body mass index lower than 18.5 kg/m2 or higher than 30 kg/m2 is associated with increased mortality, after correlating for other risk factors like age, gender, and smoking. Epidemiological studies (Icelandic Heart Association) indicate that body mass index 31 – 32 kg/m2 is associated with a 40% higher mortality than BMI 23 – 24 kg/m2 .

  • Although your BMI can give you a general idea of your overall health risks, it still doesn’t tell you whether you are carrying muscle weight or excess fat.
  • BMI measurements should be interpreted cautiously when used for people who are petite, who have large body frames or who are highly muscular.