Objective: To explore if the secular trend in height is contributing to delay overweight rise among Brazilian adolescents.
Design: Changes in BMI mean over time were fitted using linear regression including as independent variables survey year, height, survey-specific income quintiles, age and an interaction term of height × survey year. Overweight was defined as BMI≥25·0 kg/m2. Changes in overweight prevalence over time were fitted using Poisson regression.
Setting: Four national household surveys: 1974/5, 1989, 2002/3 and 2008/9.
Subjects: Brazilian adolescents.
Results: Mean values of height and BMI increased over the period, for both sexes and in all age ranges, except for girls aged 14-19 years from 1989 to 2002/3. The highest average increment and mean rate of height were between 1989 and 2002/3 and in 10-15-year-olds. The annual increment of height decreased from 2002/3 to 2008/9 in parallel with the increment in BMI rate. After fitting the regression model, the height × survey year interaction and per capita income were strong vectors to increase BMI mean. Changes in increment rate of height played a protective role against overweight in the last two periods for both sexes, mainly for girls. The period from 1989 to 2002/3 was the strongest vector associated with overweight in boys and the association decreased to the next period, from 2002/3 to 2008/9.
Conclusions: BMI and height of adolescents have increased in a wavering and alternate way throughout four decades in Brazil. The rate of height increment has played a protective role against overweight in adolescents.
Keywords: Adolescents; Growth; Overweight; Secular trend.