Trends in body mass in Swedish adolescents between 2001 and 2007

(1) Compare BMI standard deviation scores (BMIsds) in 16-year olds in 2001 and 2007 to assess trends. (2) Describe tracking of BMIsds between ages 10 and 16 years, in a longitudinal 6-year follow-up. (3) Identify possible predictors in 2001 for high BMIsds in 2007 and increase in BMIsds between 2001 and 2007.

A six-year follow-up study on 296 subjects, aged 10 years at baseline and a panel study among 16-year olds. BMIsds was used as the main outcome. RESULTS. No difference in BMIsds in 16-year-old adolescents was found between 2001 and 2007. Strong tracking (r = 0.80, 95% CI: 0.75-0.84) was found for BMIsds between ages 10 and 16 years. Low aerobic capacity and high BMIsds at age 10 years predicted overweight at age 16 years. High BMIsds in 2001 predicted a decline in BMIsds (OR: 0.58, 95% CI: 0.43-0.76) and high level of self-reported moderate-to-vigorous physical activity predicted an increased BMIsds (OR: 1.38, 95% CI: 1.13-1.67).

There was no difference in prevalence of overweight plus obesity between the 2001 and 2007 samples. Normal weight and good aerobic fitness in 10-year-old children seems to decrease the risk of elevated relative BMI in 16-year olds.