1. What is BMI?

Body Mass Index (BMI) is a person's weight in kilograms divided by the square of height in meters. It is a simple screening method for weight categories that may lead to health problems according to NHLBI (National Heart, Lung, and Blood Institute) guidelines.

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. It's a quick screening tool to identify potential weight problems in adults.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What are the BMI categories according to NHLBI?
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 those with muscular builds, and underestimate it in older persons who have lost muscle mass.

Q3: Should children use this calculator?
A: No, children and teens need age- and sex-specific percentiles rather than the adult categories.

Q4: What are the health risks of high BMI?
A: Higher BMI is associated with increased risk of heart disease, high blood pressure, type 2 diabetes, gallstones, and certain cancers.

Q5: What's a healthy BMI for older adults?
A: Some research suggests BMI range of 25-27 may be optimal for older adults rather than the standard 18.5-24.9.