What is Body Mass Index?
Body Mass Index (BMI) is a simple measure calculated from height and weight, used worldwide as a quick initial tool to estimate whether a person's weight is appropriate for their height. The formula: weight in kilograms divided by height in meters squared.
BMI Categories According to the World Health Organization
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25 – 29.9 | Overweight |
| 30 and above | Obese |
Limitations of BMI
BMI is a screening tool, not a precise diagnosis, because it doesn't distinguish between muscle weight and fat weight. For example, an athlete with high muscle mass might show a BMI in the "overweight" range even though their actual body fat percentage is low. BMI also doesn't account for fat distribution in the body, age, or individual differences.
Frequently Asked Questions
Is BMI accurate for everyone?
No, it's a general indicator suitable for most adults, but it's less accurate for athletes with high muscle mass, pregnant women, older adults, and children (who have different scales). In these cases, it's best to consult a specialist for a more accurate assessment.
Does the formula differ by sex?
The calculation formula itself doesn't differ between men and women, but interpreting the result and body fat distribution can differ, which is why BMI remains a general guidance tool rather than a substitute for a comprehensive medical evaluation.