You asked

How will the doctor determine whether my child is overweight?

Your child’s doctor will measure his height and weight and plot these numbers on a growth chart. Doctors today make use of a new series of growth charts which take into consideration of a child’s Body Mass Index (BMI), which indicates whether his height and weight are in proportion. The BMI is a better indicator of whether your child is carrying too much body fat than a weight measurement alone.
While the BMI of an adult is calculated with a straight formula, children’s BMIs are based on gender and age, to allow for the change in body composition that happens as a child gets older.
Like a standard growth chart, your child will be ranked in percentiles compared to his peers. If your child’s BMI is in the 85th percentile, which means that it’s higher than that of 85 percent of children his age and gender then he would be considered overweight. If he’s in the 95th percentile, he would be considered obese.
In addition to your child’s height and weight, his doctor will also factor in how much his parents weigh, how long he has been heavy and his overall health.

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