BMI is a number calculated by dividing a person’s weight in kilograms by his or her height in meters squared. BMI is used in determining obesity.
Obesity is most commonly calculated using BMI. An adult with a BMI of 30 or greater is clinically obese.
BMI is not used to determine a person’s actual percentage of body fat, but it is a good indicator to categorize weight in terms of what is healthy and unhealthy.
MEASURING OBESITY IN CHILDREN
Weight-to-age percentiles are used to measure obesity in children. However, it should be kept in mind that this method, among other methods, should only be used as a tool. Only a physician can best determine and diagnose weight status in your child.
Plotting Your Child's Weight-to-Age Percentile
To plot your child's weight-to-age percentile, find the age of your child on the bottom of the chart and look to the left to locate their body weight. Once you locate their weight and age, locate the corresponding shaded color on the bottom of the chart to determine your child's percentile.
A child is defined as "overweight" if their weight-to-age percentile is greater than 95 percent. A child is defined as "at risk for overweight" if their weight-to-age percentile is greater than 85 percent and less than 95 percent.