1. What is BMI?

BMI (Body Mass Index) is a simple index of weight-for-height that is commonly used to classify underweight, normal weight, overweight and obesity in adults according to MOH NZ guidelines.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

Explanation: BMI 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 is an important screening tool to identify potential weight problems in adults. According to MOH NZ guidelines:

• Underweight: BMI < 18.5
• Normal weight: BMI 18.5-24.9
• Overweight: BMI 25-29.9
• Obese: BMI ≥ 30

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: Is BMI accurate for everyone?
A: BMI may not be accurate for athletes (who may have high muscle mass), pregnant women, the elderly, or children.

Q2: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat mass, and doesn't account for fat distribution.

Q3: How often should I check my BMI?
A: For most adults, checking BMI annually is sufficient unless you're making significant lifestyle changes.

Q4: Does BMI differ by ethnicity?
A: Some ethnic groups may have different health risks at the same BMI levels, but MOH NZ uses standard categories.

Q5: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentile charts.