Frequent consumption of fast food has been associated with increased body mass index (BMI) (1). In the USA, the diets of children and adults increasingly includes fast food (2). Eating fast food has been associated with higher intakes of energy, fat, sodium, added sugars and sugar-sweetened beverages, and lower intakes of fruits, vegetables, fibre and milk in children (3), adolescents (4) and adults (5). Fast food also tends to have higher energy densities and poorer nutritional quality than foods prepared at home and in comparison with dietary recommendations (2). A recent review on US neighbourhood environments reported fast food restaurants are more prevalent in low-income and ethnic minority areas, possibly contributing to economic and ethnic obesity disparities (6). The authors of this review proposed requiring fast food restaurants locate a minimum distance from schools and limiting the total number of per capita fast food restaurants in a community. Policy makers have been making decisions related to fast food availability; for example, Los Angeles enacted a fast food ban (7).
Evidence-based environmental and policy approaches to obesity are important, because interventions primarily targeting individual-level behaviours, such as eating more fruits and vegetables, have had generally modest, mixed or null effects on sustaining weight loss (8,9). Recognizing these shortcomings and the complexity of eating and activity behaviours, obesity research and interventions are increasingly using ecological approaches that link multi-level factors (e.g. individual food choices with environmental and policy influences) (10). To effectively investigate the food environment and shape-effective strategies to improve access to healthy foods, valid and reliable measures are needed (11).
In light of these limitations and given the interest in using ecological approaches, this systematic review aims to examine the methodology and current evidence on fast food access and its associations with outcomes. The end goal of the review is to identify gaps with data collection and measurement, understand the limitations of previous research and designs and focus future research on areas in most need of attention.