What is overweight according to BMI?

Appeared in: P.CHO-2019

Explanation

Body Mass Index (BMI) is a measure used to assess weight status, calculated as weight in kilograms divided by the square of height in meters (kg/m²).
According to the World Health Organization (WHO), the 'overweight' category for adults begins at a BMI of 25.0 kg/m².
The full range for overweight is 25.0 to 29.9 kg/m². A BMI of 30.0 kg/m² or higher is classified as obesity.
Therefore, a BMI greater than 25.0 kg/m² correctly identifies the starting point for being classified as overweight.

Option A: A BMI greater than 18.5 kg/m² includes the normal weight range (18.5-24.9 kg/m²) and is therefore not specific to the definition of overweight.
Option C: A BMI less than 25.0 kg/m² defines the categories of normal weight and underweight, not overweight.
Option D: A BMI less than 18.5 kg/m² is the specific definition for the 'underweight' category.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Body Mass Index (BMI) classification for overweight as background academic context rather than a clinical decision trigger.
Nurses frequently use BMI as a quick screening tool to identify patients at risk for weight-related health problems, such as type 2 diabetes, hypertension, cardiovascular disease, and certain cancers.
A high BMI is a critical data point that prompts further assessment, patient education on diet and exercise, and potential referral to a dietitian or specialist.
What if? If a patient from an Asian population has a BMI of 24 kg/m², they might still be considered at increased risk. Some guidelines recommend lower BMI cut-offs for Asian populations (e.g., overweight at >23.0 kg/m²), as they can have a higher percentage of body fat at a lower BMI, increasing their risk for metabolic diseases.

How to Approach the Question

First, understand the question is asking for the specific definition of 'overweight' using the Body Mass Index (BMI) scale.
Recall the standard BMI formula: weight (kg) / [height (m)]².
Mentally review or recall the key cut-off points for the BMI categories: Underweight (<18.5), Normal (18.5-24.9), Overweight (25.0-29.9), and Obese (≥30.0).
Evaluate each option against these standard classifications.
Option B (>25.0 kg/m²) correctly identifies the lower threshold for the overweight category. While the overweight range has an upper limit, this option is the best descriptor among the choices provided.

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

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