Fast food outlets, physical activity facilities, and obesity among adults: a nationwide longitudinal study from Sweden

Background While neighborhood deprivation is a well-known predictor of obesity, the mechanisms behind this association are unclear and these are important to clarify before designing interventions focusing on modifiable neighborhood environmental factors in order to reduce obesity risk. Objectives This study examined the longitudinal association between availability of fast-food outlets and physical activity facilities and the risk of obesity among adults. Methods This study used multiple national register data from Sweden. During the 11-year follow-up period between 2005 and 2015, data from 1,167,449 men and 542,606 women, aged 20-55 years, were accessible for inclusion in this analysis. Incidence of obesity was identified based on a diagnosis of obesity during the follow-up period derived from clinical register data. Neighborhood availability of fast-food outlets and physical activity facilities were assessed in 2005 and Cox regression was used in the statistical analysis. Individual socio-demographic factors and neighborhood deprivation were used as covariates. Results There were no meaningful associations between neighborhood fast-food outlets or physical activity facilities and obesity in men or women. Neighborhood deprivation was, however, consistently and strongly associated with incidence of obesity in both men and women. Conclusions Availability of fast-food outlets and lack of physical activity facilities appear unlikely to cause obesity in Swedish adults. Other potentially modifiable environmental factors within specific social and cultural settings that may influence obesity risk should be examined in future studies.