Trends in body mass index and overweight prevalence among children and adolescents in the region of Aragon (Spain) from 1985 to 1995

OBJECTIVE: To analyse trends in body mass index (BMI) and overweight prevalence for children and adolescents in the region of Aragon (Spain), from 1985 to 1995. DESIGN: Nine cross-sectional examinations of schoolchildren conducted yearly from 1985 to 1995. SUBJECTS: A total of 90,997 children (45,970 males and 45,027 females) in the first school year (6 - 7 y of age); 106,284 scholars (52,772 males and 53,512 females) in the last school year (13-14 y of age). MEASUREMENTS: Heights and weights were measured and BMI (kg/m(2)) was calculated. RESULTS: We observed a trend to higher BMI values across the surveys, by sex and age. The secular trends in BMI showed the largest increases at the upper ends of the distribution, especially in males. In children in the first school year, prevalences of overweight were higher in females than in males (P < 0.001); however, in adolescents in the last school year, prevalences were higher in males than in females (P < 0.001). We observed a significant trend in overweight prevalence from 1985 to 1995 in children from the first school year (P=0.0183, in males and P=0.0168, in females). In children in the last school year there was only a significant trend in males (P<0.0001). CONCLUSION: Significant changes in BMI occurred in the population studied during the period 1985 - 1995, but these changes differ by age and sex. The increasing skewness of BMI in the upper percentiles of the population, especially in boys, suggests that, not only is the pediatric population getting fatter, but the fatter members are becoming more obese. Our results also show a striking increase in the prevalence of overweight children in the region of Aragon (Spain) during the 1985-1995 decade.