A variety of different terms, metrics, and cut-off values have been used to describe and assess overweight and obesity in children. Body mass index (BMI) calculated as weight in kilograms divided by height in meters squared can be used to express weight adjusted for height. In order to account for variability by sex and age, BMI in children is compared to sex- and age-specific reference values. In the United States, the Centers for Disease Control and Prevention (CDC) 2000 growth charts serve as reference values. The terminology used for high BMI-for-age in children in the United States to date has been based on the recommendation of an expert committee convened by federal agencies. This committee recommended the use of BMI and defined overweight as a BMI-forage at or above the 95th percentile of a specified reference population and the designation of "at risk for overweight" for BMI values between the 85th and the 95th percentiles of BMI for age. More recently, although the cut-off values and the interpretation have not changed, changes in terminology were proposed. An American Medical Association expert committee report retained the two cut-off values of the 85th and 95th percentiles of BMI-for-age but used different terminology, referring to BMI-for-age from the 85th up to the 95th percentile as "overweight" and to BMI-for-age at or above the 95th percentile as "obesity." The National Center for Health Statistics (NCHS) and other CDC publications will continue to include prevalence estimates at the 85th and 95th percentiles as before but will change the terminology to use the term "overweight" for a BMI-for-age between the 85th and 95th percentile (formerly called "at risk for overweight") and the term "obesity" for a BMI-for-age at or above the 95th percentile (formerly called "overweight").