Andrew Selous is MP for South West Bedfordshire and Chair of the All-Party Parliamentary Group on Obesity.

This summer will mark two years since the Government’s Childhood Obesity: A Plan for Action was published. Since then, some vital progress has been made.

Notably, the Soft Drinks Industry Levy has been announced and, ahead of its implementation in April, has already led to the significant reduction of sugar in many drinks. Just last week Public Health England announced its plans for industry reformulation measures to help cut calorie consumption.

Yet with over 1 in 3 children found to obese or overweight in the latest National Child Measurement Programme, it is clear more work is needed.

In adulthood, excess weight increases the risk of thirteen types of cancers, as well as type 2 diabetes and heart disease. The NHS is spending at least £5.1 billion a year on overweight and obesity-related ill-health in England.

An obese child is around five times more likely to be an obese adult, so tacking obesity early must be a priority. And it is increasingly apparent that policy change which addresses obesity will benefit more than just the health of young people.

The environment we live in can take the power and choice of diet away from young people and parents, so it is vital to identify where change can be made. There is no one simple solution to tacking children’s obesity, and grassroots, community actions like ‘The Daily Mile’ remain important initiatives.

But the prevalence of junk food advertising and the increasing popularity of on-demand and social media marketing threatens these successful initiatives. Tackling the obesity crisis requires a cultural change, and that’s why, as part of the next phase of the Childhood Obesity Plan, the Government must prioritise reducing the tsunami of adverts for junk foods reaching our children.

Introducing a 9pm watershed on adverts for food and drinks high in fat, salt and sugar (HFSS), alongside reducing exposure to marketing methods like celebrity endorsements and toy giveaways, will help to reduce our obesogenic environment.

Research into the role advertising plays in diet and weight has continually demonstrated how influential junk food marketing can be on young people, particularly those from more deprived backgrounds. A series of reports from Cancer Research UK has identified that young people are more likely to eat hundreds more items of junk food, like crisps and biscuits, every year if they watch a lot of commercial TV, indicating that TV adverts are a clear risk factor for weight gain in children.

Indeed, findings from the Obesity Health Alliance  show that the highest spending crisp, confectionary and sugary drinks brands put over £143 million a year into advertising – dwarfing the amount spent on public health messaging. The industry clearly knows the impact their adverts can have on consumption.

Cancer Research UK also found that young people who remembered having seen a junk food advert every day, either on TV, social media or in the street, were more than twice as likely to be obese than those who couldn’t remember seeing any in the last month. Evidently, HFSS influences both the diet and weight of young people, and the environment we have allowed to flourish drives these behaviours.

The findings were especially striking for young people from deprived backgrounds. It is well known that obesity is strongly linked to socioeconomic deprivation, and junk food marketing exacerbates this. The reportA Prime Time for Action, published yesterday, found young people in the poorest UK households recalled seeing substantially more junk food adverts on TV compared to the most affluent households. It is the poorest children in society, therefore, who have the most to gain from tighter restrictions.

Acting to reduce exposure to junk food adverts is a key step towards improving health outcomes for young people. This is not about restricting what we can or cannot feed our children, but a 9pm watershed can reduce harmful subconscious or impulse buys and empower children and parents to control their consumption habits, rather than be driven by ‘pester-power’.

Ofcom data suggests that the popularity of evening and family shows has significantly increased among young people, however these programmes are not covered by existing advertising regulations, which were introduced in 2008. In the past 10 years viewing habits have radically changed, and it is time for our response to junk food advertising to catch up.

Updating decade old regulation to include a 9pm watershed, and recognising and appropriately regulating the rapid increase in on-demand viewing, is an important step to match the changing influences of junk food marketing on young people. It won’t solve the obesity crisis on its own, but it will be the sort of cultural change we need to start turning the tide.