Health
BMI Calculator: What Your Number Really Means
Body Mass Index (BMI) is widely used but often misunderstood. This guide explains what it measures, where it falls short, and how to use health calculators effectively.
What Is BMI?
BMI is calculated from your height and weight. It was originally a population-level statistical tool.
The WHO categories are:
- Underweight: below 18.5
- Normal: 18.5 – 24.9
- Overweight: 25 – 29.9
- Obese: 30+
For Asian populations, thresholds are lower. Taiwan uses BMI 24 for overweight and 27 for obesity.
The Limitations of BMI
BMI is popular but has significant blind spots:
- Doesn't distinguish muscle from fat
- Ignores fat distribution
- Varies by ethnicity and age
Better Metrics Alongside BMI
For a more complete picture, track these too:
- Waist circumference
- Waist-to-hip ratio
- Body fat percentage
- TDEE
How to Use Health Calculators Effectively
- Use multiple calculators together
- Track trends, not single readings
- Consider your context
- Calculate your calorie needs
Conclusion
BMI is a useful starting point — not a final verdict. Use it as part of a bigger health picture.