Body composition
BMI
LOINC 39156-5 · kg/m2
Ranges
Reference range: 18.5–24.9 kg/m2
What it is
Body Mass Index (BMI) is your weight relative to your height. It is a quick screen for whether your weight is in a healthy range.
Why it matters
It is a simple, population-level guide to weight-related health risk, though it does not measure body fat directly.
What high values can mean
A higher value can indicate overweight or obesity, linked to higher risk of several conditions — but muscular people can read high too.
What low values can mean
A lower value can indicate being underweight, which carries its own health considerations.
How to improve it
Gradual changes through balanced eating and regular activity move BMI toward a healthy range; consider waist size too.
Food & lifestyle
A balanced, mostly whole-food diet and regular activity support a healthy weight; crash diets rarely last.
Preparing for the test
Calculated from your height and weight; measure weight at a consistent time, ideally in the morning.
When to talk to a doctor
Discuss your weight with a doctor in the context of waist size, body composition and overall health.
Related markers
Sources
- CDC
- MedlinePlus (NIH)
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
See your own values in context
Bllod turns your lab report PDFs into clear, tracked results — every marker organized, explained, and charted over time.