Learn about Body Mass Index (BMI) medical tests, including what the tests are used for, why a doctor may order a test, how a test will feel, and what the results may mean.
Body mass index (BMI) is an estimate of body fat based on height and weight. It doesn’t measure body fat directly, but instead uses an equation to make an approximation. BMI can help determine whether a person is at an unhealthy or healthy weight.
A high BMI can be a sign of too much fat on the body, while a low BMI can be a sign of too little fat on the body. The higher a person’s BMI, the greater their chances of developing certain serious conditions, such as heart disease, high blood pressure, and diabetes. A very low BMI can also cause health problems, including bone loss, decreased immune function, and anaemia.
Doctors can easily calculate BMI from the heights and weights they gather at each check-up.
For adults 20 years old and older, BMI is interpreted using standard weight status categories. These categories are the same for men and women of all body types and ages. The standard weight status categories associated with BMI ranges for adults are shown in the following table.
BMI | Weight Status |
---|---|
Below 18.5 | Underweight |
18.5 – 24.9 | Normal or Healthy Weight |
25.0 – 29.9 | Overweight |
30.0 and Above | Obese |