Why Your BMI Calculator Might Be Lying to You
For decades, the Body Mass Index (BMI) has been the gold standard for a quick health check. You step on a scale, measure your height, and get a number. If it is over 25, you are “overweight.” If it is over 30, you are “obese.”
It seems scientific, but there is a major flaw: BMI was designed almost entirely using data from White European men.
When we apply that same mathematical formula to South Asian, Arab, or Black bodies, the results can be dangerously misleading. Here is why one size definitely does not fit all.
1. The “Hidden Risk” for South Asian and Arab People
For many people of South Asian and Middle Eastern descent, the standard BMI chart is too lenient. You could have a “healthy” BMI of 22 or 23, yet still suffer from the health issues usually associated with obesity, like Type 2 diabetes or heart disease.
The Reason: Visceral Fat European bodies often store fat subcutaneously—meaning right under the skin. You can pinch it. South Asian and Arab bodies, however, have a genetic tendency to store fat differently: visceral fat.
Visceral fat is stored deep inside the abdomen, wrapping around vital organs like the liver and pancreas. You cannot see or pinch this fat, which is why some doctors call this being “skinny fat” (or TOFI: Thin Outside, Fat Inside).
Because visceral fat is much more toxic and damaging to your metabolism than arm or leg fat, the health risks kick in much earlier.
The Adjustment: Health experts now recommend that for these populations, the danger zone shouldn’t start at a BMI of 25. It should start lower, often at 23.
2. The “Muscle Myth” for Black People
On the other side of the spectrum, the standard BMI calculation often punishes Black people unfairly.
The Reason: Bone Density and Muscle Mass BMI is a very simple calculation: it measures heaviness, not fatness. It cannot tell the difference between a pound of fat and a pound of muscle.
Studies have shown that Black people, on average, tend to have higher bone mineral density and higher muscle mass than White populations. Muscle and bone are denser and heavier than fat.
Because of this, a Black person might step on the scale and register a high BMI number (labeling them as “overweight”), even if they have very low body fat and are in excellent metabolic health.
The Consequence: This leads to “false alarms,” where healthy individuals are pressured to lose weight they don’t need to lose, while the actual markers of health (like blood pressure or cholesterol) are ignored.
What Should We Do Instead?
The takeaway isn’t that BMI is useless, but that it is a blunt instrument. It is a rough guess, not a medical diagnosis.
If you are South Asian, Arab, or Black, trusting the standard numbers blindly can lead to two opposite errors:
False Comfort: Thinking you are healthy because you are “thin,” while dangerous fat builds up around your organs.
False Panic: Thinking you are unhealthy because you are “heavy,” when you are actually just strong.
The Better Metric: The Tape Measure A much better way to gauge your risk is measuring your waist circumference. Regardless of your weight or ethnicity, a growing waistline is the strongest indicator of future health risks.