1. What is BMI?

Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in meters squared. A BMI under 18.5 is considered underweight.

2. How Does the Calculator Work?

The calculator uses the BMI equation:

Where:

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

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

3. Importance of BMI Calculation

Details: BMI is used to screen for weight categories that may lead to health problems but it is not diagnostic of body fatness or health of an individual. Underweight (BMI < 18.5) may indicate malnutrition, eating disorders, or other health problems.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For pounds and inches, convert first (1 kg = 2.2 lbs, 1 m = 39.37 inches). All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

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

Q2: Is BMI accurate for everyone?
A: BMI may overestimate body fat in athletes and underestimate it in older people who have lost muscle mass.

Q3: What are risks of being underweight?
A: May include osteoporosis, decreased immune function, fertility issues, and developmental delays in children.

Q4: Should children use this calculator?
A: Children's BMI is interpreted differently using age and sex-specific percentile charts.

Q5: What's a healthy way to gain weight?
A: Focus on nutrient-dense foods, eat more frequent meals, include healthy fats, and combine with strength training.