Trends in BMI among Belgian children, adolescents and adults from 1969 to 1996

OBJECTIVE: To document secular data on changes in the distribution of body mass index (BMI), to determine the probability of overweight at 40 y of age in Belgian males in relation to the presence or absence of overweight at d ifferent ages in adolescence, and to estimate tracking of BMI in Belgian ma les in Belgium aged 12-40 y. DESIGN: Cross-sectional and mixed longitudinal surveys in nationally repres entative samples of Belgian males and females. SUBJECTS: Cross-sectional - more than 21 000 boys and 9698 girls; to examin e secular trends - 3164 boys and 5140 girls; to examine tracking - 161 male s. MEASURES: Body mass and height to determine BMI. RESULTS: In Belgian children the degree of overweight has increased between 1969 and 1993. Tracking of BMI is high in adolescence (r = 0.77) and adult hood (r = 0.69-0.91) and moderate from adolescence to adulthood (r = 0.49). In Belgian males, the probability of overweight at 40 y of age in the pres ence of overweight at different ages in adolescence is important (odds rati os 5.0-6.9). CONCLUSIONS: Cross-sectional and longitudinal data, trends and tracking of BMI from 1969 until 1996 in Belgium indicate an increase in the degree of c hildhood overweight and obesity. Moreover, the risk of an overweight male a dolescent becoming an overweight adult is substantial. Measures to restrict the Belgian overweight and obesity epidemic should be taken.