I agree that BMI should not be a good method, especially for children. This is my grandson at age 7 or so when the pediatrician told my DiL that his BMI put him well into the overweight catetgory:


We all say he must have inherited his dad's heavy bones, as here is a photo of his dad (my son) on his wedding day, when his BMI put him at borderline obese despite having a 32-inch waist and wearing a men's medium in T-shirts.