Body mass index
| Body mass index (BMI) | |
|---|---|
Body mass index across heights and weights: Underweight Normal weight Overweight Moderately obese Severely obese Very severely obese | |
| Synonyms | Quetelet index |
| MeSH | D015992 |
| MedlinePlus | 007196 |
| LOINC | 39156-5 |
| Part of a series on |
| Human body weight |
|---|
Body mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m2, resulting from mass in kilograms (kg) and height in metres (m).
The BMI is a convenient rule of thumb used to broadly categorize a person as based on tissue mass (muscle, fat, and bone) and height. Major adult BMI classifications are underweight (under 18.5 kg/m2), normal weight (18.5 to 24.9), overweight (25 to 29.9), and obese (30 or more). When used to predict an individual's health, rather than as a statistical measurement for groups, the BMI has limitations that can make it less useful than some of the alternatives, especially when applied to individuals with abdominal obesity, short stature, or high muscle mass.
BMIs under 20 and over 25 have been associated with higher all-cause mortality, with the risk increasing with distance from the 20–25 range.