The Body Mass Index
```
(BMI)
```

is the ratio of the body mass the square of the height in meters.

\begin{equation} bmi = \frac{m}{h^2} \end{equation}

where $m$ is the body mass en $h$ the height of a person.
The BMI is an indication of a person's total body fat and does not measure the body fat directly. It is a moderate correlation with direct measures of body fat. The index can be used as a screening tool for determining whether a person is underweight, has a normal weight, has overweight or is obese.
The BMI classification uses the following guidelines: underweight
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(≤18.5)
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, healthy weight
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(18.5–24.9)
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, overweight
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(25.0–29.9)
```

, and obese
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(≥30.0)
```

.