What is BMI?
Body Mass Index (BMI) is a numerical value calculated from your weight and height. It's one of the most widely used screening tools for weight-related health risks. The formula was developed by Adolphe Quetelet in the 19th century and is still used globally by healthcare professionals today.
The BMI Formula
BMI is calculated using the following formula:
BMI = weight (kg) / height² (m)
For example, if you weigh 70 kg and are 1.75 m tall: BMI = 70 / (1.75 × 1.75) = 22.9
BMI Categories
BMI RangeCategoryHealth Risk Below 16Severe UnderweightVery High 16 – 18.5UnderweightHigh 18.5 – 24.9Normal WeightLow 25 – 29.9OverweightModerate 30 – 34.9Obese (Class I)High 35+Obese (Class II+)Very HighLimitations of BMI
While BMI is a useful screening tool, it has significant limitations:
- Doesn't distinguish muscle from fat — Athletes may have a high BMI despite being very fit
- Doesn't account for fat distribution — Visceral fat (belly fat) is more dangerous than subcutaneous fat
- Not accurate for all ages and ethnicities — Different thresholds may apply for Asian populations
- Doesn't consider bone density — Elderly individuals may have low BMI but high fat percentage
Better Alternatives to BMI
Consider combining BMI with these additional measurements for a more complete picture:
- Waist circumference (risk increases at >40 inches for men, >35 inches for women)
- Body fat percentage (measured via DEXA scan or bioelectrical impedance)
- Waist-to-height ratio