Adolescent obesity in a low-income Mexican American district in South Texas

Background: The Third National Health and Nutrition Examination Survey, 198 8-1994 (NHANES III) revealed that 11.5% of adolescents were obese. The NHAN ES III sample size for Mexican Americans was small. Objective: To determine the prevalence of adolescent obesity in a South Tex as population that is preponderantly low-income Mexican Americans. Design: Cross-sectional prevalence study. Setting: All secondary school campuses of one rural independent school dist rict with a low-income Mexican American population. Subjects: Four thousand three hundred seventy-five students, aged between 1 2 and 17 years, enrolled in 4 secondary school campuses of 1 Rio Grande Val ley, South Texas, independent school district for academic year 1998-1999. Main Outcome Measures: Body mass index (BMI) was calculated for all 4375 st udents using weights and heights measured by school nurses on enrollment. E ach student's BMI was then plotted on a sex-specific chart and the percenti le range for age was determined. Those within the 85th to the 95th percenti le were classified as at risk for obesity and those above the 95th percenti le were classified as obese. Results: Of 2149 adolescent girls and 2226 adolescent boys, 18% were at ris k for obesity and 22.1% were obese. A to tal of 40.1% had a BMI at the 85 t h percentile or higher for age and sex. The prevalence of obesity also cont inues to rise even after puberty more markedly in adolescent girls than ado lescent boys. Furthermore, the mean BMI progressively increases with age an d is generally at the 85th percentile or higher. Conclusions: Our data revealed a much higher prevalence rate of obesity in this adolescent Mexican American population than the rate obtained in NHANE S III. It is even higher than the rate specific for Mexican American adoles cents in NHANES III. The NHANES III significantly underestimates the preval ence of adolescent obesity in preponderantly impoverished Mexican American adolescents. This consequently leads to underestimation of the public healt h risks as well as the present and future cost of health care associated wi th obesity in this population.