Body mass index (BMI) is a measure of weight adjusted for height, calculated as weight in kilograms divided by the square of height in meters (kg/m2). Although BMI is often considered an indicator of body fatness, it is a surrogate measure of body fat because it measures excess weight rather than excess fat.
When using BMI, it’s important to consider its clinical limitations as it measures excess weight rather than excess body fat, and factors like age, sex, ethnicity, and muscle mass can affect its accuracy in assessing body composition and fat distribution.
The standard weight status categories associated with BMI ranges for adults are:
- Below 18.5: Underweight
- 18.5 – 24.9: Normal
- 25.0 – 29.9: Overweight
- 30.0 and above: Obese
Alternative body fat measurement methods may be more accurate than BMI (like waist circumference), but they may be invasive, not widely available, or challenging to standardize, making BMI the recommended choice for routine clinical practice.
Studies have shown that BMI levels correlate with body fat and with future health risks, but it doesn’t consider all factors, including genetics and fitness level.
This text was summarized from the CDC.