Calculate the BMI category of a person with a height of 1.4 m and a weight of 80 kg.

Appeared in: DSSSB October 2024

Explanation

The Body Mass Index (BMI) is calculated using the formula: Weight (kg) / [Height (m)]².
Using the given values: BMI = 80 kg / (1.4 m × 1.4 m) = 80 / 1.96 = 40.8 kg/m².
According to the World Health Organization (WHO) classification, a BMI of 40.0 or greater is categorized as Obesity Class 3 (morbid obesity).
The calculated BMI of 40.8 clearly falls into this category.

Option A: The 'Overweight' category corresponds to a BMI range of 25.0 to 29.9. The calculated BMI of 40.8 is significantly higher than this range.
Option B: The 'Normal' weight category corresponds to a BMI range of 18.5 to 24.9. The calculated BMI of 40.8 is far above this healthy range.
Option D: The 'Obesity Class 1' category corresponds to a BMI range of 30.0 to 34.9. The calculated BMI of 40.8 exceeds this range.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain BMI Calculation and Classification as background academic context rather than a clinical decision trigger.
Nurses use BMI as a quick and essential screening tool to identify patients at risk for weight-related health problems, including cardiovascular disease, type 2 diabetes, hypertension, and certain cancers.
A patient with Class 3 Obesity (morbid obesity) requires special nursing considerations, such as using bariatric equipment (beds, lifts) for safety, meticulous skin assessment to prevent pressure ulcers, and monitoring for respiratory complications.
What if? If the person's height were 1.8 m instead of 1.4 m, their BMI would be 80 / (1.8 × 1.8) = 24.7 kg/m², placing them in the 'Normal' weight category. This demonstrates the critical impact of height on the BMI calculation.

How to Approach the Question

First, identify the given values from the question: weight = 80 kg and height = 1.4 m.
Recall the standard formula for Body Mass Index (BMI): BMI = weight in kilograms / (height in meters)².
Calculate the square of the height: 1.4 m × 1.4 m = 1.96 m².
Perform the division: 80 kg / 1.96 m² = 40.816 kg/m².
Compare the calculated BMI (approximately 40.8) to the standard WHO BMI classification categories.
A BMI of 40.8 falls into the 'Obesity Class 3' range, which is defined as a BMI of 40.0 and above.

Concept Tested & Keywords

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart C (pp 404-604 of 604) p. 69-71

E6 Medicine Davidson Principles Practice 24e p. 720-722

Practise the full DSSSB October 2024

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