The interpretation of BMI can vary depending on age groups. For adults aged 18 and older, a BMI between 18.5 and 24.9 is generally considered healthy. However, for children and adolescents, BMI is assessed differently. It is compared to age and sex-specific growth charts, providing percentiles that indicate how a child's BMI compares to others of the same age and sex. The interpretation of BMI percentiles varies for different age groups and is best evaluated by healthcare professionals who have access to age-specific growth charts.