The use of planning policy to manage and create a healthy food environment has become a popular policy tool for local governments in England. To date there has been no evaluation of their short-term impact on the built environment. We assess if planning guidance restricting new fast food outlets within 400 m of a secondary school, influences the food environment in the local authority of Newcastle Upon Tyne, UK. We have administrative data on all food outlets in Newcastle 3 years pre-intervention 2012–2015, the intervention year 2016, and three years’ post-intervention 2016–2019. We employ a difference-in-difference approach comparing postcodes within the school fast food outlet exclusion zone to those outside the fast-food exclusion zones. In the short term (3 years), planning guidance to limit the number of new fast-food outlets in a school exclusion zone did not have a statistically significant impact on the food environment when compared with a control zone.