Changes in adiposity and body mass index from late childhood to adult life in the Trois-Rivières study.

This study explored tracking of the body mass index (BMI) in a representative subgroup of subjects (95 women and 96 men) who were involved in the Trois-Rivières Growth and Development Study by testing autocorrelations between data for 10, 11, and 12 years and corresponding values at 34 years of age. Tracking of skinfold measurements (subscapular, triceps, suprailiac, and abdominal, and their sum) over the same intervals (60 women and 52 men) was also evaluated. After the age of 12 years, subjects showed a similar development of absolute values, whether they were from the experimental or the control group. Gains of the BMI and skinfold thicknesses showed expected gender differences. In particular, men showed larger gains of the BMI and abdominal skinfolds, whereas women had larger gains in the triceps skinfold. Increases in the sum of four skinfolds did not differ significantly between men and women, suggesting that the larger BMI gains in men were caused by a larger relative increase of fat-free mass in the men. Tracking coefficients for the BMI were lower in men than in women between 10, 11, 12, and 34 years (r = 0.43-0.49 vs. r = 0.64-0.70, P < 0.001). The results indicate that the body composition of participants in the Trois-Rivières Growth and Development study developed in a similar fashion whether or not their primary school instruction included additional physical education instruction. The results also suggest that prediction of adult obesity based on childhood BMI measurements is more effective in girls than in boys.