1. The Body Mass Index (BMI) is a widely used measure to assess a person's body fatness and overall health status.2. The formula for calculating BMI is weight in kilograms divided by the square of height in meters.3. A BMI of less than 18.5 indicates being underweight.4. A BMI range of 18.5 to 25 is considered normal weight.5. A BMI range of 25 to 30 is classified as overweight.6. A BMI range of 30 to 35 is categorized as class I obesity.7. A BMI range of 35 to 40 falls under class II obesity.8. A BMI of 40 or higher is classified as class III obesity.9. BMI is not applicable for children and adolescents because their bodies are developing and BMI fluctuates with growth.10. For teenagers aged 15 to 20, the definitions of overweight and underweight do not use fixed BMI values, as BMI changes with development.11. Different countries and regions establish their own criteria for overweight and underweight based on the local distribution of healthy BMIs among children.12. This is typically done using the average BMI and its standard deviation of healthy children to determine the boundaries for overweight and underweight.13. Children whose BMI falls within the 85th to 95th percentile of the normal distribution are at risk for overweight.14. Modern smart scales can quickly measure a variety of health indicators, making it convenient to check one's health status while shopping.