In the past, there has been some confusion about terms such as obesity, risk of obesity, overweight, morbid obesity, and others. This subject has become much clearer because of a major review of the subject of childhood obesity done by an expert committee under the auspices of the American Medical Association and two parts of the U.S.
Health and Human Services Department: the Health Resources Service Administration and the CDC. They reviewed the entire subject of childhood obesity and made recommendations in December 2007 in the journal Pediatrics, published by the American Academy of Pediatrics (see Resources). The first objective of the committee was to standardize the definitions used.
Being obese or overweight means having too much body fat compared with the normal or healthy weight. Because a healthy weight is also a function of height, the definitions used now are based on the BMI, which,as noted previously, is a number calculated from weight and height. Table 2 shows the healthy range of BMI to be in the percentile range of 5% to 85%, corresponding to BMIs between 18.5 and 24.9. Overweight, using this definition, is a BMI of 25 to 29.9. By using the calculator or tables, you can then take your child’s height to see where the cutoff weight is for the healthy category.
Healthy range of BMI.
Status BMI Percentile Range BMI numbers
Underweight < 5% < 18.5
Healthy 5% to 85% 18.5 to 24.9
Overweight 85% to 95% 25 to 29.9
Obese > 95% ≥ 30
Extreme obesity > 99% > 40
You or your child’s doctor can use the CDC tables to calculate your child’s status. For example, if your son is 8 years old, 49 inches (4 feet 1 inch) tall and weighs 100 pounds, his BMI is 29.3. He is over-weight. Now looking at the table for boys in Appendix B, you will see that the 25th percentile for his age and height is 50 lbs. That is, 1/4 of all boys weigh less than 50 lbs. and 3/4 weigh more. Continuing:
The 50th percentile is 55 lbs. The 75th percentile is 64 lbs. The 90th percentile is 72 lbs. The 95th percentile is 77 lbs.
So, at 100 lbs., he is heavier than 95% of all boys his age and height—this is too much. To get down to the area you want to realistically be at, between roughly 50% and 95%, he would need to drop his weight from 100 lbs. to below 77 lbs. and ideally to around 60 lbs. The available tables can be difficult to use and the ideal weight and BMI for your child may be complex to calculate, but using an online calculator (see the Resources for examples) can give you a quick and easy answer.