Abstract
BACKGROUND: Since 2013, front-of-pack traffic light labels have been implemented voluntarily on packaged food in the UK. The UK Government is now considering alternative labelling approaches which may be more effective, such as Chile's mandatory nutrient warning labels. The present study aimed to estimate the impact of mandatorily implementing (i) traffic light labels and (ii) nutrient warning labels on population-level obesity prevalence and mortality in England. METHODS: A microsimulation model was built to simulate the effects of implementing mandatory front-of-pack nutrition labels (nutrient warning and traffic light) on assumed changes in daily energy intake from packaged food (due to consumer behaviour change and reformulation), and subsequent population-level obesity prevalence and mortality due to changes in BMI. We modelled the population of England, aged 30-89 years, over 20 years (2024-2043) using a synthetic population stratified by age, sex and Index of Multiple Deprivation. The model simulates individuals' life courses and counterfactuals under different policy scenarios, allowing detailed assessment of policies on exposures, disease risk, and mortality. FINDINGS: Compared to the baseline scenario (current voluntary implementation of traffic light labelling), mandatory implementation of traffic light labelling was estimated to reduce obesity prevalence by 2.34 percentage points (95% UI 0.67-4.31) and prevent or postpone 57,000 (95% UI 13,000-160,000) obesity-related deaths. Mandatory implementation of nutrient warning labelling was estimated to have a larger impact; a 4.44 percentage point (95% UI 0.08-10.76) reduction in obesity prevalence and 110,000 (95% UI 2000-420,000) fewer obesity-related deaths. INTERPRETATION: This work offers the first modelled estimation of the impact of introducing mandatory front-of-pack nutrition labels on obesity prevalence in the adult population in England. Findings suggest that mandatory implementation of nutrient warning labels would reduce prevalence of obesity and related deaths, compared to current voluntary or mandatory implementation of traffic light labelling, and should therefore be considered by the UK Government. FUNDING: European Research Council.