Child growth → BMI-for-age

Adult BMI categories use the same cutoffs for everyone because adult body composition is relatively stable. Children's body fat percentage changes predictably with age, so a BMI of 18 might be appropriate for one age and concerning for another. Percentiles compare each child to others at exactly the same age and sex.

Children typically reach their lowest BMI around ages 5-6, then BMI gradually increases through adolescence. This is called "adiposity rebound." An earlier-than-expected rebound (before age 5) may be associated with higher weight later in life.

Children of parents with higher BMIs tend to have higher BMIs themselves, partly from genetics and partly from shared environment. A child's BMI should be interpreted in the context of their family.

Generally, 5th to 85th percentile is considered healthy weight. Below 5th suggests underweight; 85th to 95th is overweight; above 95th is obese. But these are screening categories. A child slightly above 85th who is active and eats well may be perfectly healthy.

Talk to your pediatrician, who will look at growth trends, family history, and activity level. They may suggest small lifestyle adjustments or simply continued monitoring. Avoid putting children on restrictive diets without medical guidance.

Yes. BMI can't distinguish muscle from fat. An active, athletic child may have a BMI in the "overweight" range while having healthy body composition. Mention activity level to your pediatrician.

Depends on age and maturity. For young children, percentiles aren't meaningful to share. For older children and teens, some awareness may be appropriate, framed carefully. Focus on healthy habits, not numbers.