What is BMI?
BMI (Body Mass Index) = Weight (kg) ÷ Height² (m²). It is a simple screening tool to assess if a person is underweight, normal, overweight or obese. It does NOT measure body fat directly.
BMI = Weight (kg) ÷ Height² (meters)
Example: 70kg, 5'7" (1.70m) → BMI = 70 ÷ (1.70×1.70) = 24.2
Example: 70kg, 5'7" (1.70m) → BMI = 70 ÷ (1.70×1.70) = 24.2
BMI Categories for Indians
WHO recommends lower BMI cutoffs for South Asians because Indians tend to have more visceral fat (dangerous belly fat) at lower BMIs compared to Caucasians:
| BMI | WHO Category | Indian Guideline |
|---|---|---|
| Below 18.5 | Underweight | Underweight |
| 18.5–22.9 | Normal | Normal |
| 23–24.9 | Normal (WHO) | Overweight risk |
| 25–29.9 | Overweight | Obese I |
| 30+ | Obese | Obese II |
Limitations of BMI
- Does not distinguish between muscle and fat (athletes can have high BMI)
- Does not account for fat distribution (belly fat is more dangerous)
- Same BMI threshold for men and women (women naturally have more fat)
- Age not considered — BMI of 27 means different things at 25 vs 65
Better Together: BMI + Waist Circumference
Use BMI alongside waist circumference for better health assessment. Indian guidelines: Men waist > 90cm, Women > 80cm = high metabolic risk regardless of BMI.
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