Body mass index (BMI) is a measure of body fat based on height and weight that applies to both adult (16 year and older) men and women.
The Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to both adult men and women. Though it does not actually measure the percentage of body fat, it is a useful tool to estimate a healthy body weight based on how tall a person is. Due to its ease of measurement and calculation, it is the most widely used diagnostic tool to identify obesity problems within a population.
- less than 18.5 = Underweight
- 18.5 - 24.9 = Normal weight
- 25 - 29.9 = Overweight
- Above 30 = Obesity
- Above 35 = Severely obese
- Above 40 = Morbidly obese
- Above 50 = Superobese
When BMI can be Misleading
- In Athletes: The BMI can be misleading in athletes (such a body builders) who have a low body fat percentage, but deliver an excessive BMI as they have a significant increase in muscle mass. As the index is a calculation of weight and height alone, it assumes that the increase is due entirely to body fat.
- In Children: The BMI can be misleading in children, as body fatness changes over the years as they grow, and girls and boys also differ in their body fatness as they mature. In children it is better to express weight as a percentile value, in which it is compared to others at the same age and sex.
- In Ethnic Groups: For some ethnic groups the BMI values need to be modified. For Chinese, Indian and Malaysian people, a BMI greater than 23 is regarded as overweight and a BMI greater than 27.5 is regarded as obese.