Neighbourhood convenience stores and childhood weight outcomes: an instrumental variable approach

The association between the commercial food environment and childhood obesity is increasingly assessed in the literature, but little is known about the role of convenience stores, an important food retail format worldwide. This study helps bridge the gap using individual-level data containing measured body mass index (BMI) for public schoolchildren and geo-coded residence and store locations in Arkansas, United States. The distance from residence to the nearest highway is employed to instrument neighbourhood convenience store exposure, while controlling for possible confounding effects of other food stores. We find that exposure to at least one convenience store exposure is associated with a BMI z-score increase of 0.162 SD, and exposure to each additional convenience store is associated with a BMI increase of 0.071 SD. There is no evidence for a larger association among children from low-income families or those with limited access to healthy foods.