BMI

What it is

BMI (body mass index) is a number calculated from your height and weight, used as a quick, population-level screen for whether your weight might be worth discussing. It doesn't measure body fat directly and can't tell muscle from fat, so athletic or very muscular people may read “high” without excess fat, and it can under-flag others. It's most useful viewed alongside measures like waist size and metabolic markers rather than on its own.

Typical range

Reference ranges vary between laboratories, and what is normal for you depends on your own history. Your own lab’s range is the one printed on your report.

Worth asking your clinician

• Given my build and muscle mass, how meaningful is my BMI as a health signal for me?
• Would a waist measurement or body-composition test add useful context to my BMI?
• Is my BMI something we should track over time, or stable enough not to worry about?