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The Numbers Tool

Body Mass Index

BMI is a useful signal — not a diagnosis, not a verdict. Use the sliders, get your number, then read what it means and where it falls short.

Underweight < 18.5
Healthy 18.5 – 24.9
Overweight 25 – 29.9
Obese ≥ 30
170cm
70kg

Ideal Weight for Your Height

53 kg72 kg

✓ You are within the healthy weight range

You're in the range — but a number doesn't tell the whole story. Someone can sit here with excellent blood work and terrible energy, or vice versa. Keep doing what works. Pay attention to how you sleep, how you recover, and how you feel — not just where the scale lands.

BMI only knows two things: your height and your weight. It can't see muscle mass, bone density, or where fat is stored. Treat it as a starting signal — not a conclusion.

18.5253024.2YOUR BMIHEALTHY
Underweight1018.5
Healthy18.525
Overweight2530
Obese3040+

Context

What your number won't tell you

01

Your muscle can fool it

A rugby player and someone who's genuinely overfat can share the exact same BMI. The formula doesn't care whether your extra weight is muscle, fat, or water. If you train regularly, this number is even less reliable for you — and will almost always read higher than your actual health suggests.

02

Where fat lives matters more

Two people with identical BMIs can have very different health risks depending on where their body stores fat. Visceral fat — packed around organs in the abdomen — behaves differently to fat stored under the skin. Waist circumference is a blunter tool, but it tells you more about metabolic risk than BMI alone.

03

It was never built for this

BMI was invented by Adolphe Quetelet, a Belgian mathematician, in the 1830s — as a statistical tool to describe the average European man at a population level. It was never designed to assess individual health, and was never tested across different ethnicities, ages, or body compositions. That context matters.