The question behind the number
People often ask why their BMI says “overweight” when they train regularly, or why two people with the same BMI can look and feel very different. The answer is built into the formula: BMI compares weight with height. It does not separate fat, muscle, bone or fluid, and it does not show where body fat is carried.
What BMI can do well
BMI is quick, inexpensive and useful for broad adult screening. It can help start a conversation about health risk, especially when it is considered with waist measurements, blood pressure, laboratory results, medical history and daily habits.
Where interpretation changes
- Muscular athletes may have a high BMI without high body fat.
- Children and teenagers need age- and sex-specific growth references.
- Pregnancy, oedema and major changes in muscle mass require different interpretation.
Use the result as a signal to ask better questions, not as a diagnosis or a label about your body.