Aim: To identify risk factors for overweight and obesity in Portuguese children.
Methods: A cross-sectional study of children 7 to 9.5 y old was performed between October 2002 and June 2003. A total of 2,274 girls and 2,237 boys were observed. Weight and height were measured, and parents filled out a questionnaire about family characteristics. Overweight and obesity, using age- and sex-specific body mass index (BMI) cut-off points as defined by the International Obesity Taskforce, were used.
Results: After adjustment for age and sex, the odds ratio for childhood obesity increased by television viewing (reference 0-2 h; 2-3 h: 1.51; 3-4 h: 1.72; 4 h: 1.63), paternal obesity (reference <18.5 kg/m(2); 25.0-29.9: 3.06; 30.0: 7.09), maternal obesity (reference <18.5 kg/m(2); 25.0-29.9: 9.06; 30.0: 18.13) and birthweight (reference <2,500 g; 2,500-3,000 g: 1.55; 3,000-3,500 g: 1.87; 3,500-4,000 g: 2.13; 4,000 g: 2.74), and decreased by sleeping duration (reference 8 h/d; 9-10 h/d: 0.44; 11 h/d: 0.39), paternal education (reference primary school; secondary: 0.91; university: 0.42), maternal education (reference primary school; secondary: 1.13; university: 0.56), being a single child (reference yes; no: 0.56) and family size (reference one child; two children: 0.59; three children: 0.44; more than four children: 0.37).
Conclusion: Our data support the perspective that education about energy intake and energy expenditure should be used much earlier in those families with high-risk children, namely those with high parental BMI or high birthweight. Protective factors were parental education and family size.