INFLUENCE OF DIET, PHYSICAL-ACTIVITY AND PARENTS OBESITY ON CHILDRENSADIPOSITY - A 4-YEAR LONGITUDINAL-STUDY

OBJECTIVE: To assess the relationships between diet, body composition, physical activity, parents' obesity and adiposity in children at the age of 8 y and four years later. STUDY DESIGN: Prospective observation al study of anthropometric measures initiated in 1992, follow-up exami nation in 1996. METHODS: 112 prepubertal (age: 8.6 +/- 1.0 y) children were studied. Energy and nutrient intakes were assessed by diet histo ry, body composition by anthropometry and physical activity, by a ques tionnaire. Obesity was defined as relative body mass index (BMI) (rel BMI) > 120%, where rel BMI = (BMI/BMI at 50th centile for age and gend er) x 100. RESULTS: Prevalence of obesity was not statistically differ ent at baseline (22.3%) than four years later (19.8%): rel BMI at the age of 8 y was positively self-related with rel BMI at the age of 12 y (r = 0.73, P < 0.001). After four years, eight (32%) obese children b ecame non obese and five (6%) non obese children became obese. Multipl e regression analysis (stepwise procedure) revealed that, in the final equation, the mother's BMI and TV viewing (independent variables) acc ounted for 17% of the children's rel BMI variance at the age of 8 y (R = 0.42, P < 0.001) while the parents' BMIs accounted for 13.5% of the children's rel BMI variance at the age of 12 y (R = 0.37, P < 0.001). Other variables such as total energy intake, nutrient intake percenta ge and amount of physical activity, were all rejected. An autoregressi ve unbalanced measures model regression analysis recognised the mother 's and father's BMIs as the only variables able to predict rel BMI in the children (mother's BMI coeff. 2.53 (s.e.m. 0.26), P < 0.0001; fath er's BMI coeff. 2.07 (s.e.m. 0.23), P < 0.0001). A multivariate logist ic regression analysis was also performed. The children who participat ed in the follow-up, were divided into two groups based on the positiv e or negative change in the rel BMI between final and baseline measure ments. Of all the variables considered, only rel BMI at baseline was s elected in the final equation. Other variables such as age, gender, en ergy and nutrient intake, TV viewing and amount of physical activity, as well as the parents' BMI, were all removed. CONCLUSIONS: The parent s' obesity was the main risk factor for obesity in this group of child ren. Sedentary behaviour (TV viewing) was independently associated wit h overweight at the age of 8 y. Physical activity and energy and nutri ent intakes did not significantly affect the change in rel BMI over th e four-year period when the parents' obesity was taken into account.