Understanding BMI: Useful Tool Or Outdated Metric?

What BMI actually measures

Body Mass Index is just weight divided by height squared — a simple ratio, originally designed for population-level statistics, not individual diagnosis.

Where it falls short

BMI can't distinguish between muscle and fat. A muscular athlete can register as 'overweight' on the scale despite having low body fat, while someone with normal BMI can carry an unhealthy amount of visceral fat with little visible muscle.

Why it's still used

It's cheap, fast, and correlates reasonably well with health risk at a population level — useful for large-scale screening, even if it's a blunt instrument for any one individual.

Alternative individual measurements worth knowing

Waist circumference alone — generally considered a health concern above roughly 90cm for men and 80cm for women, though guidelines vary — is a simpler, more individually meaningful measurement than BMI for assessing health risk related to body fat distribution.

How to use BMI appropriately, if at all

As a rough starting point for a broader conversation with a healthcare provider, rather than a definitive individual verdict, BMI still has some practical use — the mistake is treating it as a precise, standalone measure of an individual's health.

It's also worth adding that BMI categories were developed using data that didn't always represent the full diversity of body types and ethnicities, which is part of why some health organizations now recommend supplementing it with additional individual measurements for a more complete picture.

Better individual markers

Waist circumference (a rough proxy for visceral fat), waist-to-hip ratio, and simply how your body composition looks and functions tell a more complete story than BMI alone for any single person.