What should be the normal Body Mass Index (BMI) of an adult man?

Appeared in: Raj. CHO -2020

Explanation

The World Health Organization (WHO) defines a normal BMI range for adults as 18.5 to 24.9 kg/m².
The option 20-25 falls entirely within this established normal range.
This range is associated with the lowest risk of comorbidities related to weight.
BMI values are generally age-independent and the same for both sexes in adults.

Option A: A BMI range of 15-19 is classified as underweight (a BMI below 18.5). This is not a normal or healthy weight range and is associated with its own set of health risks.
Option C: A BMI range of 26-30 falls into the overweight (25.0-29.9) and obese class I (starting at 30.0) categories. This range is associated with an increased risk of comorbidities.
Option D: A BMI range of 31-35 is classified as Obesity Class I (30.0-34.9). This is associated with a moderate risk of developing health problems like diabetes and cardiovascular disease.

Visual 1: Chart - A colorful chart illustrating the different BMI categories (Underweight, Normal, Overweight, Obesity) with their corresponding numerical ranges. This provides a quick visual reference for the classifications.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Body Mass Index (BMI) Categories as background academic context rather than a clinical decision trigger.
Nurses use BMI as a quick, non-invasive screening tool to identify patients who may be at risk for health problems due to their weight. It's a starting point for conversations about nutrition and physical activity.
A high BMI alerts the nurse to screen for related conditions such as hypertension, dyslipidemia, and type 2 diabetes.
What if? If a patient is a bodybuilder with a BMI of 28, the nurse should not automatically classify them as overweight without further assessment. The nurse should consider waist circumference, body composition, and overall physical health, as the high BMI is likely due to increased muscle mass, not excess fat.

How to Approach the Question

First, recall the standard medical definition of Body Mass Index (BMI) and its categories as defined by health organizations like WHO.
Remember the key numerical cut-offs: <18.5 (Underweight), 18.5-24.9 (Normal), 25.0-29.9 (Overweight), and ≥30.0 (Obese).
Evaluate each of the given options against these standard ranges.
Option '15-19' is mostly Underweight.
Option '20-25' fits perfectly within the Normal range.
Options '26-30' and '31-35' fall into the Overweight and Obese categories.

Concept Tested & Keywords

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E6 textbook of Applied Biochemistry and Nutrition & Dietetics 2nd Edition Harbans Lal (pp 26-464 of 479) p. 26-464

Practise the full Raj. CHO -2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.