BMI, waist and hip
BMI is one number among several, and the least informative of them on its own. Waist tells you something BMI cannot, and it takes a tape measure and thirty seconds.
Measuring your waist properly — most people do it wrong
- Measure on bare skin, not over clothes.
- Find the top of the hip bone and the bottom of the ribs; the tape goes midway between them, not at the narrowest point and not at the navel.
- Stand upright, arms down, feet together.
- Breathe out normally and measure at the end of that breath — do not suck in.
- The tape should sit flat and snug without pressing into the skin.
- Measure the same way each time, or the series is worthless.
What BMI cannot tell you
It cannot tell muscle from fat, so a very muscular person and a sedentary one can share a figure. It says nothing about where weight sits, which is the part that matters most. The cut-offs were derived largely from European populations and are applied differently elsewhere. And in children it does not work this way at all — children are read against growth charts for their age and sex, never against adult figures.
What is worth watching instead
Your own series over months. One reading places you against a crowd; a line across a year places you against yourself, and that is the comparison a clinician can actually use. Record weight and waist together in the home health log and bring the chart, not one number.
Worth asking
- With my build and history, which of these numbers is the one to watch?
- Has anything changed since my last measurement, and does that change matter?
- Which single change would make the biggest difference in my case?
- Do any of my medicines affect weight?