Universal free school meals and children's bodyweight. Impacts by age and duration of exposure.

We study the impact on children's bodyweight of switching from means-tested to universal provision of nutritious free school meals in England. We exploit the roll-out of universal provision across Local Authorities to estimate effects at different ages and durations of exposure, based on nurse-collected, population-wide health data for state school children. Exposure to universal free lunches reduces obesity prevalence and BMI among children aged 4-5 and 10-11, but older children's bodyweights are less responsive than younger children's.