What is BMI?
Body Mass Index (BMI) is a simple screening measure that estimates body fat based on height and weight. It is calculated by dividing your weight in kilograms by the square of your height in metres:
For example, a person weighing 70 kg and standing 1.70 m tall has a BMI of 70 ÷ (1.70 × 1.70) = 24.2.
Standard WHO BMI Categories
| BMI Range | Category (International) | Category (Asia-Pacific) |
|---|---|---|
| Below 18.5 | Underweight | Underweight |
| 18.5 – 22.9 | Normal | Normal |
| 23.0 – 24.9 | Normal | Overweight (At Risk) |
| 25.0 – 29.9 | Overweight | Obese Class I |
| 30.0+ | Obese | Obese Class II |
Why Indians Need Different Cut-Offs
The standard WHO BMI thresholds (overweight at 25, obese at 30) were developed using data from European populations. Multiple studies — including research published in The Lancet and by the Indian Council of Medical Research (ICMR) — have shown that South Asians develop metabolic complications like type 2 diabetes, cardiovascular disease, and hypertension at lower BMI values compared to Caucasians.
This is because Indian body types tend to carry more visceral (abdominal) fat relative to overall weight. A BMI of 23 in an Indian person may carry the same metabolic risk as a BMI of 25 in a European person. The WHO Asia-Pacific guidelines therefore lower the overweight threshold to 23 and the obese threshold to 25 for Asian populations.
Healthy Weight Range by Height (Asia-Pacific Cut-offs)
| Height | Healthy Weight Range (BMI 18.5–22.9) |
|---|---|
| 5'0" (152 cm) | 42.7 – 52.9 kg |
| 5'2" (157 cm) | 45.6 – 56.5 kg |
| 5'4" (163 cm) | 49.1 – 60.8 kg |
| 5'6" (168 cm) | 52.2 – 64.6 kg |
| 5'8" (173 cm) | 55.4 – 68.6 kg |
| 5'10" (178 cm) | 58.6 – 72.5 kg |
| 6'0" (183 cm) | 62.0 – 76.7 kg |
BMI Limitations — When It Does Not Tell the Full Story
- Muscular individuals: BMI cannot distinguish between muscle mass and fat. A gym-goer with significant muscle may have a "overweight" BMI despite low body fat. Use the Body Fat Calculator alongside BMI for a better picture.
- Elderly adults: BMI may underestimate fat in older adults who have lost muscle mass (sarcopenia). A "normal" BMI in a 70-year-old may still indicate excess fat.
- Children and teenagers: BMI-for-age percentiles (from CDC or WHO growth charts) should be used instead of adult thresholds.
- Pregnant women: BMI is not applicable during pregnancy. Pre-pregnancy BMI is used to guide recommended weight gain during pregnancy.
Waist Circumference — A Better Predictor for Indians
For Indian adults, waist circumference is often a better predictor of metabolic risk than BMI alone. The ICMR recommends these thresholds:
- Men: Waist circumference above 90 cm indicates increased risk
- Women: Waist circumference above 80 cm indicates increased risk
If your BMI is in the "normal" range but your waist circumference exceeds these limits, you may still be at elevated risk for metabolic diseases. This is sometimes called "normal weight obesity" or "thin fat" phenotype — and it is particularly common in the Indian population.
What To Do With Your BMI Result
BMI is a screening tool, not a diagnosis. Use it as a starting point:
- If your BMI is below 18.5, consult a doctor or dietitian to rule out nutritional deficiencies or underlying conditions
- If your BMI is 18.5–22.9, maintain your current weight with balanced nutrition and regular physical activity
- If your BMI is 23–24.9 (overweight by Asian standards), focus on portion control, reducing processed foods, and increasing daily movement
- If your BMI is 25+, consider consulting a healthcare provider for blood sugar, cholesterol, and blood pressure screening
Check your current BMI with the BMI Calculator. For a more detailed body composition estimate, also try the Body Fat Calculator.