The test
Waist-to-height ratio
Your waist divided by your height. It tells you where you carry weight, which matters more than what you weigh, and it is the only measurement here that needs nothing but a tape.
What you need. A tape measure.
How to do it
Doing it properly
- Measure your waist at the midpoint between the bottom of your ribs and the top of your hip bones, at the end of a normal breath out.
- Measure your height.
- Both in the same units.
What counts
Your waist divided by your height. Below 0.5 is the threshold NICE uses as an early health indicator.
What most people get wrong
- Measuring at the trouser line rather than the natural waist.
- Holding the breath in.
- Pulling the tape tight.
The evidence
What it actually shows
Waist divided by height. Below 0.5 is the threshold NICE uses as an early indicator, and the arithmetic is simple enough that you can check it yourself: keep your waist under half your height.
It is reported because where weight sits is more informative than how much of it there is. Two people at the same weight and height can sit either side of this line.
It is reported as a flag, not scored into your Index. A single ratio is not a capacity measurement, and the Index measures capacity.
A threshold is not a percentile. Being under 0.5 is not a score and does not place you anywhere; it means you are on the better side of one line.
The measurement is easy to take badly. Taken over clothing, after a meal, or with the tape in a different place than last time, the number moves more than you do.
Threshold: NICE guidance on waist-to-height ratio as an early indicator.
The next step
One test is one test.
This measures one thing. The Evolution Index measures nine, across the three domains that decide how long you stay useful, and reports your weakest rather than your average — a strong heart does not buy you out of a floor you cannot get up from.
Every score is published with the error around it, because a change smaller than the measurement error is not a change.