Influence of the family nucleus on obesity in children from northeastern Brazil: a cross-sectional study

BACKGROUND: Obesity is considered to be caused by a combination of heredity and environmental factors with typical onset during childhood. The aim of this study was to identify family risk factors for the development of obesity in children from Brazil. METHODS: Cross-sectional study with 699 children, randomly and proportionally selected, ranging from 5 to 9 years of age, from public and private schools in Feira de Santana-BA. Overweight and obesity were defined using IOTF standards. Analyses of the interviews with the children's guardians were used to determine the influence of the family nucleus on obesity. RESULTS: The children were classified into four groups based on weight percentiles (underweight, normal, overweight and obese). Significant differences between the groups in relation to ethnicity, social and economical status (ρ = 000.0 for all) were found. The following variables were associated with the development of childhood obesity: fathers' obesity (ρ = 0.001), mothers' (ρ = 0.021) and both parents' (ρ = 0.000). There was no significant statistical difference between fathers and mothers who did (ρ = 0.81) or did not work out (ρ = 0.15). Obesity (ρ = 0.07) tended to be less prevalent in the child whose parents were separated. Family history of obesity (OR = 3.3; IC = 2.0 – 5.5; ρ = 0.000) and high social class (OR = 3.0; IC = 1.1 – 7.7; ρ = 0.020) were predictive and independent associated factors. CONCLUSION: This study confirms the influence of genetic and/or behavioral factors on the origin of childhood obesity. Thus, effective intervention strategies must be focused not only on the children but on the entire family nucleus.