Which of the following statements is NOT true about body mass index (BMI)?
Obesity-related health risks increase when BMI is 30 ?or more.
It is a ratio of body weight in kilograms to squared height in meters (??????2).
BMI categories can be applied to any population except for children.
A healthy weight for height is generally defined by a BMI between 18.5-24.9.
BMI is a crude measure and does not consider body composition.
The correct answer and explanation is :
The correct answer is:
“BMI categories can be applied to any population except for children.”
Explanation:
Body Mass Index (BMI) is a widely used tool to assess whether an individual has a healthy weight relative to their height. It is calculated using the formula:
[
BMI = \frac{\text{weight (kg)}}{\text{height (m)}^2}
]
While BMI is useful for identifying potential weight-related health risks, it has limitations. One major limitation is its applicability across different populations, including children.
Why is this statement incorrect?
BMI categories can be applied to children, but they are assessed differently than adults. For children and adolescents (ages 2-19), BMI is interpreted using percentile charts rather than fixed categories. These percentiles consider age and sex since body fat distribution changes with growth and development. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) provide age- and sex-specific growth charts to classify children’s BMI as:
- Underweight: Below the 5th percentile
- Healthy weight: 5th to 85th percentile
- Overweight: 85th to 95th percentile
- Obese: Above the 95th percentile
Why are the other statements true?
- Obesity-related health risks increase when BMI is 30 or more – This is true because high BMI is linked to diabetes, heart disease, and other conditions.
- BMI is a ratio of weight to height squared – This correctly defines BMI.
- A healthy BMI range is 18.5-24.9 – This is the standard classification for normal weight in adults.
- BMI does not consider body composition – This is true, as BMI does not distinguish between fat, muscle, or bone mass.
Thus, the incorrect statement is about BMI categories not applying to children, as BMI percentiles are used instead.