The body mass index (BMI) is a rough guide to obesity that is simple to apply, but does not take account of body shape, muscle bulk and fitness. Most elite athletes, particularly those in strength sports such as wrestling and throwing, have a very high BMI. It is a poor indicator of fat in contrast to total body weight.
The BMI is calculated by the formula:-
Weight in kilograms/height in metres squared
Thus, a person weighing 70 Kg. and with a height of 1.7 metres would have a BMI of:- 70/1.72 = 24.3, which is satisfactory.
With a weight of 80 Kg., the same person has a much higher BMI thus:- 80/1.72 = 27.7, which may be overweight. BMI ranges and their standard interpretations are:-
- Under 20 – Underweight
- 20-25 – Healthy Weight
- 25-29 – Overweight
- 29-35 – Obese
- Over 35 – Severely Obese
These interpretations must be used with great caution, particularly in muscular people.