Yogesh, a 17-year-old male, has a height of 170 cm and weighs 68 kg. What is Yogesh's BMI?

Maharashtra CHO - 2020

Applied Nutrition & Dietetics

Hard

Appeared in: Maharashtra CHO - 2020

Explanation

The Body Mass Index (BMI) is calculated using the formula: Weight (in kg) divided by the square of the height (in meters).
First, the height must be converted from centimeters to meters: 170 cm is equal to 1.7 m.
Next, the height in meters is squared: 1.7 m × 1.7 m = 2.89 m².
Finally, the weight is divided by the squared height: 68 kg / 2.89 m² = 23.529...
The calculated BMI is approximately 23.52 kg/m², which falls within the normal weight range of 18.5 to 24.9 kg/m².

Option A: This option has incorrect units (kg/cm²) and an incorrect value. The BMI formula requires height in meters squared (m²), not centimeters squared (cm²). Using cm² would lead to a drastically different and incorrect result.
Option C: A BMI of 40 kg/m² is incorrect for the given weight and height. This value corresponds to Class III Obesity, indicating a weight of approximately 115.6 kg for a height of 170 cm.
Option D: This option uses inverted and incorrect units (cm/kg). BMI is a measure of mass per unit area (kg/m²), not length per unit mass. This makes the option dimensionally incorrect.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of Body Mass Index (BMI) as background academic context rather than a clinical decision trigger.
Nurses frequently calculate and monitor BMI as a quick, non-invasive screening tool to assess a patient's nutritional status and risk for chronic diseases like diabetes and cardiovascular conditions.
A sudden or significant change in BMI can be an early indicator of an underlying health issue, prompting the nurse to perform a more detailed nutritional assessment or refer the patient for further evaluation.
What if? If the 17-year-old was an elite athlete with high muscle mass, his BMI might classify him as 'overweight' even with low body fat. In such cases, BMI is less accurate, and a nurse should consider other measurements like waist circumference or skinfold thickness for a better assessment of health risk.

How to Approach the Question

Identify the question type: This is a calculation-based question requiring knowledge of a specific formula.
Recall the formula for Body Mass Index (BMI): BMI = Weight (in kilograms) / (Height in meters)².
Check the units of the given values. The weight is in kg (correct), but the height is in cm. Convert height to meters: 170 cm / 100 = 1.7 m.
Substitute the values into the formula: BMI = 68 / (1.7)².
Perform the calculation: 68 / 2.89 = 23.529...
Compare the calculated result with the given options to find the closest match, paying attention to the units (kg/m²).

Concept Tested & Keywords

Concept Tested: Calculation of Body Mass Index (BMI)
Stem keywords: BMI, height, weight, 170 cm, 68 kg
Lead-in keywords: What is
Clinical cues: Age: 17-year-old male - While specific percentile charts exist for adolescents, the standard adult BMI formula is applied here for calculation.
Clinical cues: Height: 170 cm

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