Restricting ads that promote unhealthy eating will reduce consumption

In order to find out if this policy could contribute to improvements in diet, the research team used household food and drink purchase data collected by Kantar, a commercial consumer data company, to evaluate the impact of the intervention.

Study examined purchases in nearly 1 000 households

The study ran from June 2018 to December 2019 and compared average weekly purchases of HFSS products in 977 London households, to an estimate of what would have happened without the policy. This estimate was based on the trend in purchasing in London before the policy and changes seen in households in a control area after the policy was implemented.

Assuming an average household size of 2.6 people in the sample, and an even energy distribution, the team estimated that the intervention reduced energy purchases by 385 calories per person per week – equivalent to every Londoner in the study purchasing about 1.5 fewer standard-size bars of milk chocolate per week.

“Many governments and local authorities are considering advertising restrictions to reduce consumption of high fat, salt and sugar (HFSS) products as part of obesity prevention strategies. However, evidence of the effectiveness of such policies, especially away from broadcast media, is scarce,” explained Dr Amy Yau, the study’s first author.

“Our study helps to plug that knowledge gap, showing Transport for London’s policy is a potential destination for decision-makers aiming to reduce diet-related disease more widely.”

Professor Steven Cummins, Chief Investigator of the study, noted: “The findings are particularly significant in light of the Health Bill currently going through Parliament, as they provide further evidence for the effectiveness of advertising restrictions and help support the case for the Government’s proposed ban on the online advertising of high fat, salt and sugar foods and drinks.”