Proximity to Fast-Food Outlets and Adolescent BMI: Accounting for Persistent Health Dynamics

791/2026 Yu Aoki-Beattie, Wiji Arulampalam, Neil Lloyd, Sushil Mathew

We examine the causal effect of exposure to fast-food outlets on adolescent z-BMI using data from the UK Millennium Cohort Study. We develop a novel approach to modelling persistence in adolescent BMI by clustering early childhood BMI trajectories, capturing biologically and behaviourally persistent obesity risk profiles. Including these profiles in the model allows us to separate baseline susceptibility from contemporaneous environmental effects. For identification, we exploit the near-universal transition from primary to secondary school in Great Britain, which creates plausibly exogenous variation in exposure to fast-food outlets around schools. Using this variation, we find that adolescents with at least one major-brand outlet within 400 metres of their school have, on average, a 0.158 standard-deviation higher z-BMI. Effects decline at larger distances, are limited around the home, and do not extend to other food outlets.

Gender, Health and Wellbeing