Objectives: To investigate the prevalence of overweight among different ethnic and gender groups of children and adolescents in the San Antonio, Texas, area and to compare the prevalence with that of the US national figures.

Design: Cross-sectional study

Subjects: A total of 7208 schoolchildren in kindergarten through 12th grade. There were 4215 Mexican American (MA) (58.5%), 2040 non-Hispanic white (NHW) (28.3%) and 953 African American (AA) (13.2%) subjects.

Measurements: Weight, height and skinfold thicknesses.

Results: The body mass index (BMI, kg/m2) values of MA boys were almost consistently and significantly (P<0.05) larger than NHW boys and showed a tendency to be larger than AA boys, beginning as early as age 6 and continuing through age 17. Although rarely significant, a similar trend in ethnic difference was also noted for girls, with the smallest BMI seen in NHW girls. The subscapular skinfold thickness (SST) for MA boys and girls was significantly (P<0.05) larger than that for NHW counterparts and showed a tendency to be larger than AA counterparts. No significant ethnic differences were present in the triceps skinfold thickness (TST) for girls, but MA boys' TST were occasionally larger (P<0.05) than other ethnic-gender groups. Girls' TST were frequently larger (P<0.05) than boys for each ethnic groups. Using the population data from the National Health and Nutrition Examination Survey (NHANES) I as reference, the prevalence of overweight (BMI> or =95th percentile) was greater in MA (15-28%) and AA (11-29%) boys and girls than in NHW (7-17%) counterparts. The combined prevalence of overweight and 'at risk of overweight' (BMI>85th percentile) was much larger in MA boys (40-50%), MA girls (34-52%), and AA girls (33-51%) than other subgroups. The onset of overweight is quite early, starting at 5-6 y of age, especially in girls. Compared to the data from national surveys, the prevalence of overweight found in this study is higher than reported nationally. We found a marked increase in the skinfold thickness, especially SST for boys, but the increase is less for girls.

Conclusions: The prevalence of overweight is higher in MA boys and girls and AA girls than other ethnic-gender groups in the San Antonio, Texas, area. The prevalence of childhood overweight in the San Antonio area is higher than national figures. The findings of increasing prevalence and early onset of childhood overweight are concerning, because these are known risk factors for diabetes and diseases of many other organ systems. Measures to prevent, reduce or treat childhood obesity are urgently needed.