Independent and combined associations between fast-food outlet exposure and genetic risk for obesity: a population-based, cross-sectional study in the UK

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Monsivais, P 
Sharp, SJ 
Forouhi, NG 
Wareham, NJ 

Background Characteristics of the built environment such as neighbourhood fast-food outlet exposure, are increasingly recognised as risk factors for unhealthy diet and obesity. Obesity also has a genetic component, with common genetic variants explaining a substantial proportion of population-level obesity susceptibility. However, it is not known whether and to what extent associations between fast-food outlet exposure and body weight are modified by genetic predisposition to obesity.

Methods We used data from the Fenland study, a population-based sample of 12,435 UK adults (mean age 48.6 years). We derived a genetic risk score associated with BMI (BMI-GRS) from 96 BMI-associated single nucleotide polymorphisms. Neighbourhood fast-food exposure was defined as quartiles of counts of outlets around the home address. We used multivariable regression models to estimate the associations of each exposure, independently and in combination, with measured BMI, overweight and obesity, and investigated interactions.

Results We found independent associations between BMI-GRS and risk of overweight (RR=1.34, 95% CI 1.23-1.47) and obesity (RR=1.73, 95% CI 1.55-1.93), and between fast-food outlet exposure and risk of obesity (highest vs lowest quartile RR=1.58, 95% CI 1.21-2.05). There was no evidence of an interaction of fast-food outlet exposure and genetic risk on BMI (P=0.09), risk of overweight (P=0.51), or risk of obesity (P=0.27). The combination of higher BMI-GRS and highest fast-food outlet exposure was associated with 2.70 (95% CI 1.99-3.66) times greater risk of obesity.

Conclusions Our study demonstrated independent associations of both genetic obesity risk and neighbourhood fast-food outlet exposure with adiposity. These important drivers of the obesity epidemic have to date been studied in isolation. Neighbourhood fast-food outlet exposure remains a potential target of policy intervention to prevent obesity and promote the public’s health.

Body weight, Fast-food outlet exposure, Genetic predisposition, Interaction, Obesity, Adult, Body Mass Index, Cross-Sectional Studies, Fast Foods, Female, Humans, Male, Middle Aged, Obesity, Residence Characteristics, Risk Factors, United Kingdom
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BMC Medicine
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BioMed Central
Medical Research Council (MR/K023187/1)
Medical Research Council (MC_UU_12015/1)
MRC (MC_UU_00006/1)
Medical Research Council (MC_UU_12015/5)
MRC (MC_UU_00006/3)
Cambridge University Hospitals NHS Foundation Trust (CUH) (146281)
MRC (MC_UU_00006/7)
Wellcome Trust (087636/Z/08/Z)
Economic and Social Research Council (ES/G007462/1)
Department of Health (via National Institute for Health Research (NIHR)) (NF-SI-0617-10149)
MRC (MC_UU_00006/6)
National Institute for Health and Care Research (IS-BRC-1215-20014)
This work was undertaken by the Centre for Diet and Activity Research (CEDAR), a UK Clinical Research Collaboration (UKCRC) Public Health Research Centre of Excellence. Funding from the British Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, the National Institute for Health Research, and the Wellcome Trust, under the auspices of the UK Clinical Research Collaboration, is gratefully acknowledged (grant number MR/K023187/1). TB received support from the MRC (grant number MC_UU_00006/7). The Fenland Study is funded by the MRC and the study PIs (NJW and NGF) acknowledge this support (grant numbers MC_UU_00006/1, MC_UU_00006/3, MC_UU_00006/6). NJW and NGF also acknowledge support from NIHR Biomedical Research Centre Cambridge: Nutrition, Diet, and Lifestyle Research Theme (grant number IS-BRC-1215-20014). PM received support from the Health Equity Research Center at Washington State University.