Overweight prevalence among youth in the United States: why so many different numbers?

Several recent publications have presented different estimates for the prevalence of overweight among youth in the United States. Prevalence estimates range from 11-24%, despite describing the same results from the third National Health and Nutrition Examination Survey (NHANES III). This paper discusses the variety and evolution of different overweight prevalence estimates. Issues of definition, measurements, criteria selection and comparison groups are considered and implications for estimates of the prevalence of overweight among youth are explored. Reference percentiles for body mass index (BMI) from several publications are compared. The differences in published estimates from NHANES III are noted and explained.