Body Mass Index was developed in the 1830s by a Belgian mathematician studying population weight patterns in Western Europeans. It was never designed as an individual health diagnostic tool, and the cutoffs — under 18.5 is underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight, 30 and above is obese — were calibrated on that same Western European population. For billions of people in South Asia, East Asia, and the Middle East, these cutoffs significantly underestimate cardiovascular and metabolic risk.
What the Research Shows
Multiple large-scale studies have found that South Asians — including people from Pakistan, India, Bangladesh, and Sri Lanka — develop type 2 diabetes, cardiovascular disease, and metabolic syndrome at lower BMI values than their Western counterparts. A Pakistani person with a BMI of 23 (classified as normal) may carry the same disease risk as a European person with a BMI of 27 or 28 (classified as overweight).
The World Health Organization convened an expert consultation in 2004 that reviewed evidence across Asian populations and concluded that the risk of comorbidities is significant at BMI values of 23 and above for Asian populations, compared to 25 for Western populations. Many Asian-Pacific health authorities now use action points of 23 (overweight) and 27.5 (obese) rather than the standard 25 and 30.
Why the Difference Exists
The primary reason is body composition. At the same BMI, South Asians tend to have higher body fat percentage and more visceral fat — the fat stored around internal organs in the abdominal cavity — compared to people of European descent. Visceral fat is metabolically active in harmful ways: it releases inflammatory cytokines, drives insulin resistance, and is directly associated with cardiovascular risk in ways that subcutaneous fat (stored under the skin) is not.
South Asians also have, on average, smaller bone frames and less muscle mass relative to European populations. Since BMI uses only weight and height with no adjustment for body composition or bone structure, these differences are invisible in the calculation.
What This Means in Practice
If you are South Asian and your BMI falls in the normal range (18.5-24.9), do not assume your cardiovascular and metabolic risk is the same as a European person with the same BMI. Consider getting a waist circumference measurement — the WHO recommends South Asian men aim for under 90 cm and women under 80 cm. Fasting glucose and HbA1c tests are particularly important since South Asians have significantly higher rates of type 2 diabetes at earlier ages and lower weights than Western populations.
Better Metrics to Use Alongside BMI
Waist circumference is arguably more useful than BMI for South Asians because it directly measures abdominal fat accumulation. Waist-to-height ratio — your waist circumference divided by your height, both in the same units — should ideally be below 0.5. Body fat percentage measured by DEXA scan, bioelectrical impedance, or the US Navy method gives a more complete picture than BMI alone.
The Practical Takeaway
BMI is not useless — it provides a quick population-level screen and is still a reasonable starting point. But South Asians should apply the adjusted thresholds (23 as overweight, 27.5 as obese) rather than the Western cutoffs, and should prioritize waist circumference measurement and metabolic blood tests alongside BMI. A BMI of 22 is not a clean bill of health for a Pakistani or Indian person — it warrants checking the other markers.
Conclusion
BMI was built on and for one population and then applied to the entire world. The evidence that South Asians face elevated metabolic risk at lower BMIs is strong and well-established in the scientific literature. Use BMI as a first screen, apply South Asian adjusted cutoffs, and always supplement it with waist circumference, blood glucose, and cholesterol measurements for a complete health picture.