Family and lifestyle factors mediate the relationship between socio-economic status and fat mass in children and adolescents

Aim Socio-economic status (SES) is a major determinant of childhood overweight. However, the etiology of this association and the role of family and lifestyle factors as potential mediators of this relationship remain unclear.

Methods Cross-sectional data of 4,772 girls and boys aged 5-16 years of the Kiel Obesity Prevention Study were considered in mediation analyses. Fat mass (FM) was assessed by bioelectrical impedance analyses and converted into percent fat mass standard deviation score (FM%-SDS). SES was defined by parental educational level, classified into low, middle and high. Family and lifestyle factors were obtained by validated questionnaires and considered as mediators. In three different age groups, the product-of-coefficients method was conducted to examine age-specific mediator effects on the relationship between SES and FM%-SDS (c=total effects) and their ratio to total effects, adjusted for age, sex, puberty and nationality.

Results Prevalence of overweight was 6.9 %. In all age groups, SES was inversely associated with FM%-SDS (5-7y: c₁=-0.090, p < 0.01; 9-11y: c₂=-0.167, p < 0.001; 13-16y: c₃=-0.171, p < 0.001). The relationship between SES and FM%-SDS was fully mediated by similar and age-specific mediators, concerning parental BMI, parental smoking habits, media consumption, physical activity, dwelling size and shared meals. Overall, these variables resulted in a total mediating effect of 82.2 % (5-7y), 89.9 % (9-11y) and 76.0 % (13-16y).

Conclusion Consistent for all age groups and both sexes, the relationship between SES and FM%-SDS was fully mediated by parental risk, health-related behavior and lifestyle factors. Strategies for obesity prevention should therefore address family and lifestyle factors.

Publication History

Article published online:
16 June 2020