The Body Mass Index (BMI) is a metric used to estimate body fat based on a person's height and weight. It is calculated using the following formula:

BMI = weight (kg) / height (m)

BMI Categories (WHO Standards)

• Underweight: BMI < 18.5
• Normal weight: 18.5 – 24.9
• Overweight: 25 – 29.9
• Obese (Class 1): 30 – 34.9
• Obese (Class 2): 35 – 39.9
• Obese (Class 3 - Severe Obesity): BMI ≥ 40

BMI is a general indicator of body fat but doesn't consider muscle mass, bone density, or fat distribution.