1. What is BMI?

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, normal weight, overweight and obesity in adults. It is calculated by dividing a person's weight in kilograms by the square of their height in meters.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

• \( weight \) — Body weight in kilograms
• \( height \) — Height in meters

Explanation: The formula provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems objectively with their patients.

3. Importance of BMI Calculation

Details: BMI provides the most useful population-level measure of overweight and obesity as it is the same for both sexes and for all ages of adults. However, it should be considered a rough guide because it may not correspond to the same degree of fatness in different individuals.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For New Zealand adults, the healthy weight range is a BMI between 18.5 and 24.9.

5. Frequently Asked Questions (FAQ)

Q1: What are the BMI categories for adults?
A: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obese (≥30).

Q2: Is BMI different for children?
A: Yes, BMI for children and teens is age and sex-specific and is often referred to as BMI-for-age.

Q3: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat mass, so athletes may have high BMI without excess fat. It also doesn't account for fat distribution.

Q4: What is a healthy BMI range for New Zealanders?
A: The healthy range is the same internationally: 18.5 to 24.9. However, some ethnic groups may have different health risks at the same BMI.

Q5: Should BMI be the only measure of healthy weight?
A: No, waist circumference and other factors should also be considered for a complete assessment of weight-related health risks.