Background: The relationship between socioeconomic position and
obesity has been established, however the extent to which specific behavioural
factors mediate this relationship is less clear. This study aimed to ascertain the
contribution of leisure-time physical activity (LTPA) and specific dietary
elements to social disparities in obesity within the baseline (1990-1994)
Melbourne Collaborative Cohort Study (MCCS).
Methods: 18, 489 women and 12, 141
men were included in this cross-sectional analysis. A series of linear
regression models were used in accordance with the products of coefficients
method to examine the mediating role of LTPA, alcohol, soft drink (regular and
diet), snacks (healthy and sweet), savoury items (healthy and unhealthy) and meeting
fruit and vegetable guidelines on the relationship between education and Body
Mass Index (BMI).
Results: Compared to those of lowest
educational attainment, those of the highest educational attainment had a 1kg/m2
lower BMI. Among men and women, 27% and 48% of this disparity was attributable
to LTPA and diet, respectively. Unhealthy savoury item consumption and LTPA contributed most to the
mediated effects in men and women, followed by alcohol and diet soft drink consumption
among women.
Conclusions: Diet and LTPA are
modifiable behavioural risk factors for the development of obesity which
contribute substantially to inequalities in BMI. Our findings add to the body
of knowledge around potential behavioural factors which, if effectively
targeted by public policy, could reduce social inequalities in obesity.