What BMI Can and Cannot Tell You
BMI is a population screen, not a diagnosis. Where it is useful, where it misleads, and what to measure alongside it.
2026-09-02 · Health
What it measures
Weight divided by height squared. It was designed to describe populations, and it has no idea whether the weight is muscle, fat or fluid.
Where it misleads
Athletes read as overweight. Older adults with low muscle read as normal. South Asian populations show metabolic risk at lower BMIs, which is why some guidance uses 23 rather than 25 as the upper bound.
What to measure instead
Waist circumference, waist-to-height ratio, and a trend over months. A single BMI reading says little; a direction over a year says a lot.
How to use the number
As a first flag that prompts a better measurement — not as a verdict.
Is BMI useful at all?
Yes, as a cheap screen across large groups and as a rough trend for one person.
What is a healthy BMI?
18.5–24.9 on the WHO scale.
Keep reading
FinanceWhy Your First EMI Is Mostly InterestA reducing-balance loan front-loads interest. Here is the arithmetic behind the first year, and why prepaying early saves more than prepaying late.
HomeHow Much Paint Does a Room Actually Need?Coverage per litre, coats, primer and the 10% you will wish you had bought — the arithmetic of a paint order.
PropertyMarla, Kanal and Square Feet: The 47 sq ft TrapA 10 marla plot is 2,722 sqft in Islamabad and 2,250 sqft in parts of Lahore. Here is why the same words describe different land.