1. What is BMI?

Definition: Body Mass Index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height.

Purpose: BMI is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults.

2. How Does the BMI Calculator Work?

The calculator uses the formula:

Where:

• \( BMI \) — Body Mass Index (kg/m²)
• \( W \) — Weight (kilograms)
• \( H \) — Height (meters)

Explanation: The weight in kilograms is divided by the square of height in meters to calculate BMI.

3. BMI Categories

Standard Categories:

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

4. Limitations of BMI

Details: BMI does not directly measure body fat and may not accurately reflect health for certain groups:

• Muscular individuals may have high BMI without excess fat
• Elderly may have normal BMI but reduced muscle mass
• Does not account for fat distribution
• May not be accurate for certain ethnic groups

5. Frequently Asked Questions (FAQ)

Q1: Why use BMI if it has limitations?
A: BMI remains widely used because it's simple, inexpensive, and correlates reasonably well with body fat for most people.

Q2: How accurate is BMI for athletes?
A: BMI may overestimate body fat in athletes with high muscle mass. Additional measurements are recommended.

Q3: Can BMI be used for children?
A: BMI for children is interpreted differently using age- and sex-specific percentiles rather than fixed categories.

Q4: What are alternatives to BMI?
A: Waist circumference, skinfold thickness measurements, DEXA scans, and other methods may provide more accurate assessments.

Q5: Should I rely solely on BMI for health assessment?
A: No, BMI should be considered alongside other measurements and health indicators for a complete assessment.