Risk factors for overweight and overfatness in rural South African children and adolescents

BACKGROUND: To determine risk factors for overweight/overfatness in children and adolescents from rural KwaZulu-Natal, South Africa. METHODS: Anthropometric data were collected from a cross-sectional sample (n = 1519, ages 7, 11 and 15 years) and linked to demographic information (n = 1310 and n = 1317 in overweight and overfat analyses, respectively). Candidate risk factors for overweight/overfatness were identified and tested for associations with overweight (BMI-for-age >+1SD, WHO reference) and overfatness (>85th centile body fatness, McCarthy reference) as outcomes. Associations were examined using simple tests of proportions (χ(2)/Mann-Whitney U tests) and multivariable logistic regression. RESULTS: Sex was a consistent variable across both analyses; girls at significantly increased risk of overweight and overfatness (overweight: n = 180, 73.9 and 26.1% females and males, respectively (P < 0.0001); overfat: n = 187, 72.7 and 27.3% females and males, respectively (P < 0.0001)). In regression analyses, sex and age (defined by school grade) were consistent variables, with boys at lower risk of overweight (adjusted odds ratio (AOR) 0.40 (confidence interval (CI) -0.28-0.57)) and risk of overweight increasing with age (AOR 0.65 (CI- 0.44-0.96), 0.50 (CI-0.33-0.75) and 1.00 for school grades 1, 5 and 9, respectively). Results were similar for overfatness. CONCLUSIONS: This study suggests that pre-adolescent/adolescent females may be the most appropriate targets of future interventions aimed at preventing obesity in rural South Africa.