What Is BMI and How Is It Calculated?
Body Mass Index is calculated by dividing your weight in kilograms by the square of your height in meters (BMI = kg/m²). Developed by Adolphe Quetelet in the 1830s, it remains one of the most widely used population-level health screening metrics. A BMI of 22 means your weight is 22 times the square of your height in meters, placing you squarely in the normal range.
BMI Categories and What They Mean
The World Health Organization defines four main BMI categories: Underweight (below 18.5) may indicate nutritional deficiency or underlying illness. Normal weight (18.5–24.9) is associated with the lowest health risks. Overweight (25–29.9) signals increased risk for cardiovascular disease. Obese (30+) carries significantly elevated risk for diabetes, heart disease, and joint problems.
Limitations of BMI
While BMI is a convenient screening tool, it has notable limitations. It does not distinguish between muscle and fat mass, so muscular athletes may be classified as overweight despite low body fat. It also does not account for age, sex, ethnicity, or fat distribution — factors that significantly affect health risk. Use BMI alongside waist circumference and other metrics.
When to Consult a Doctor
If your BMI falls outside the normal range, consult a healthcare provider for a comprehensive assessment. They can evaluate body composition, blood pressure, cholesterol, blood sugar, and other factors that BMI alone cannot capture. A BMI in the overweight or obese range warrants a conversation about lifestyle changes, dietary adjustments, and possible medical interventions.
