Unhealthy foods are becoming a silent epidemic, with one in seven adults and one in eight children globally now effectively addicted to ultra-processed foods. It's time to address this issue at its source: advertising. Consumption of junk food begins not with what goes in our mouths but with the messaging into our brains via advertising. UK junk food advertising is an industry worth tens of millions of pounds working to glamorise unhealthy diets. My own work looks at outdoor advertising, such as on billboards and bus stops. In 2022, among the biggest spenders on outdoor advertising were the likes of Coca-Cola, McDonald's, KFC, Subway and Müller. They spent £195m filling public spaces with monuments to fat, salt and sugar. Advertisers will say this is simply a question of choice, and that junk food ads respond to consumer demand. But do any of us feel deprived of choice by the absence of ads touting the supposed health benefits of smoking? Of course not. Society would be better off without ads for junk food on street corners. The good news? We can take action. Local authorities can introduce ethical ad policies that ban junk food ads on council-owned sites. Somerset council recently took this step, following in the footsteps of Bristol and Transport for London, whose junk food ad ban was predicted to save the NHS more than £200m. Outdoor advertising offers a poorly regulated platform for big corporations to push unhealthy diets on an unassuming public.