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010-111 · Question #108

Which of the following is a limiting factor when using the body mass index (BMI) to determine obesity and disease risk?

The correct answer is C. Fat and lean tissue weights are not differentiated. BMI's core limitation is that it derives solely from height and total body weight, making it unable to distinguish between fat mass and lean mass, which undermines its accuracy as a measure of adiposity.

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Question

Which of the following is a limiting factor when using the body mass index (BMI) to determine obesity and disease risk?

Options

  • ABody density must be computed or estimated first.
  • BSkinfold thicknesses must be measured first.
  • CFat and lean tissue weights are not differentiated.
  • DUnderestimates individuals with above average muscle mass.

How the community answered

(45 responses)
  • A
    11% (5)
  • B
    7% (3)
  • C
    80% (36)
  • D
    2% (1)

Why each option

BMI's core limitation is that it derives solely from height and total body weight, making it unable to distinguish between fat mass and lean mass, which undermines its accuracy as a measure of adiposity.

ABody density must be computed or estimated first.

Body density estimation is required for hydrostatic weighing or air displacement plethysmography; BMI requires only a scale and stadiometer with no density calculation.

BSkinfold thicknesses must be measured first.

Skinfold thickness measurements are specific to skinfold-based body composition protocols and play no role in calculating or applying BMI.

CFat and lean tissue weights are not differentiated.Correct

Because BMI is calculated only from height and weight, it treats all body mass equally regardless of whether it comes from fat, muscle, bone, or water. Two individuals with identical BMI values can have vastly different body fat percentages and therefore very different actual disease risks. This inability to differentiate tissue types can lead to misclassification of body composition and inaccurate risk stratification.

DUnderestimates individuals with above average muscle mass.

For highly muscular individuals with low body fat, BMI overestimates obesity risk by classifying them as overweight or obese, not underestimates it, making the stated direction of error incorrect.

Concept tested: BMI limitations in body composition and obesity classification

Source: https://www.cdc.gov/bmi/about/index.html

Topics

#BMI limitations#body composition#lean vs fat mass#obesity assessment

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