Do childhood social circumstances affect overweight and obesity in early adulthood?

Aims: The aim of the study was to examine the association of childhood circumstances with overweight and obesity in early adulthood, to analyse whether the respondent's education and current circumstances mediate these associations, and to explore whether the respondent's health behaviour affects these associations. Design: This was a cross-sectional study with retrospective inquiries. Methods: The study was based on a representative two-stage cluster sample (N = 1894, participation rate 79%) of young adults aged 18-29 years in Finland in 2000. The outcome measure was three-class body mass index (BMI) (normal weight, overweight, and obesity). Multinomial logistic regression was used as the main statistical tool. Results: In women, childhood circumstances (low parental education (relative risk ratio (RRR) = 2.43), parental unemployment (RRR = 2.09) and single-parent family (RRR = 1.99)) increased the risk of overweight (25 <= BMI < 30), but the effects were largely attenuated by other childhood factors and early adult circumstances. In men, no significant childhood predictors of overweight were found. Single-parent family (RRR = 2.32), parental alcohol problem (RRR = 2.71), parental mental health problems (RRR = 2.28) and being bullied at school (RRR = 3.13) predicted obesity (BMI >= 30) in women in the age-adjusted models, and being bullied at school remained a significant predictor after adjusting for all childhood and current determinants. In both genders, the strong association between parental education and obesity remained significant after adjusting for all other determinants (for the lowest educational category, RRR = 3.56 in women, and RRR = 6.55 in men). Conclusions: Childhood factors predict overweight and obesity in early adulthood. This effect is stronger on obesity than on overweight and in women than in men, and it seems to be partly mediated by adult circumstances. The results emphasize the lasting effect of childhood socioeconomic position on adult obesity. When preventive policies are being planned, social circumstances in childhood should be addressed.