Socioeconomic patterns of overweight and obesity in Scania, Sweden

Abstract: Overweight and obesity are major social and public health concerns globally. The obesity epidemic is caused by a widespread chronic energy imbalance between high-energy intake and low-energy expenditure, but this mechanism appears to be modified by a number of other biological, behavioral, and social factors that interact in a complicated manner. It has become a great challenge to understand the etiology of the global epidemic of obesity and overweight in order to design and implement policies that may counter the rapid growth of this worldwide threat to population health. Socioeconomic inequality and lifestyle factors, together with changes in the global food system and the environment, have been identified as playing a major role. The prevalence of obesity in high-income countries is greater in lower socioeconomic groups, particularly among women, but the mechanisms behind this phenomenon remain unclear, resulting in major negative implications for health equity. The overall objective of this thesis was to assess the association between socioeconomic and lifestyle factors vis-à-vis weight change, overweight, and obesity among Swedish adults in Scania, Sweden. The study population is based on the data from two waves (1999/2000 and 2005) of the Scania Public Health Cohort. It was generated from a large (n = 25,000) random selection of the adult population in the region of Scania, southern Sweden. Participants completed a self-administered postal questionnaire (baseline response rate = 59%). BMI was calculated from self-reported body height and weight. Socioeconomic status was determined by means of job title and description, or by years of education. Mediating mechanisms as well as confounding control was assessed in logistic regression models with special attention to effect-modifying interactions. Study I found that adult and childhood socioeconomic position influence weight gain, but differently by gender and age group. Two waves of socioeconomically determined weight gain patterns appeared in the population studied: one across generations and another contemporary one. Study II concluded that cohort effects play a role in BMI change. However, it was difficult to distinguish between age-period and cohort-period effects because of the linear relationship between age, period, and cohort, and due to the short follow-up. Study III showed a two-fold correlation between social capital and obesity: as a determinant in its own right, and as a modifier of the effect of socioeconomic status on obesity. Study IV demonstrated that women around retirement age with low and mid-level educations were at higher risk of weight gain over a five-year follow-up period, although this association could not be explained by changes in their leisure time physical activity or their social participation. The thesis confirmed a relationship between socioeconomic status and overweight/obesity in the population studied. However, it concluded that these relations are highly complex and dependent on a number of individual and contextual factors that vary over time, between different age groups and birth cohorts, and by gender. The concept of social capital emerged as promising in the developing of general and specific interventions for addressing obesity and overweight on the community level. Such interventions must be created for different age groups. In this regard, the period near retirement appears to play a significant role in weight gain.