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

Background: The Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III) revealed that 11.5% of adolescents were obese. The NHANES III sample size for Mexican Americans was small. Objective: To determine the prevalence of adolescent obesity in a South Texas population that is preponderantly low-income Mexican Americans. Design: Cross-sectional prevalence study. Setting: All secondary school campuses of one rural independent school district with a low-income Mexican American population. Subjects: Four thousand three hundred seventy-five students, aged between 12 and 17 years, enrolled in 4 secondary school campuses of 1 Rio Grande Valley, South Texas, independent school district for academic year 1998-1999. Main Outcome Measures: Body mass index (BMI) was calculated for all 4375 students using weights and heights measured by school nurses on enrollment. Each student's BMI was then plotted on a sex-specific chart and the percentile range for age was determined. Those within the 85th to the 95th percentile were classified as at risk for obesity and those above the 95th percentile were classified as obese. Results: Of 2149 adolescent girls and 2226 adolescent boys, 18% were at risk for obesity and 22.1% were obese. A to tal of 40.1% had a BMI at the 85 th percentile or higher for age and sex. The prevalence of obesity also continues to rise even after puberty more markedly in adolescent girls than adolescent boys. Furthermore, the mean BMI progressively increases with age and 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 NHANES III. It is even higher than the rate specific for Mexican American adolescents in NHANES III. The NHANES III significantly underestimates the prevalence of adolescent obesity in preponderantly impoverished Mexican American adolescents. This consequently leads to underestimation of the public health risks as well as the present and future cost of health care associated with obesity in this population.