Junk food adverts are set to be banned from the London Underground under new proposals unveiled on Friday by Sadiq Khan.
The plans include a ban on all adverts for food and drink high in fat, salt or sugar across the entire Transport for London network, including buses.
They have been introduced to tackle what the Mayor of London describes as a ticking timebomb of child obesity.
Shockingly, almost 40% of 10 and 11-year-olds living in the capital are either overweight or obese.
Mr Khan said: If we dont take bold steps against it we are not doing right by our young people as well as placing a huge strain on our already pressurised health service in years to come.
It cant be right that in a city as prosperous as London that where you live and the income you have can have a massive impact on whether you have access to healthy, nutritious food and your exposure to junk food advertising.
Im determined to do all I can to tackle this issue with the powers I have and help Londoners make healthy food choices for themselves and their families.
That is why Im proposing to ban adverts for harmful junk food from our entire Tube and bus network. I want to reduce the influence and pressure that can be put on children and families to make unhealthy choices.
There is a huge disparity in child obesity rates across the capital depending on where a child is growing up.
Young people from Barking and Dagenham in east London are almost twice as likely to be overweight as their counterparts from Richmond in west London.
The draft London Food Strategy also includes a proposal to ban new hot food takeaways from opening within 400 metres of schools.
Mr Khan also wants extra funding to develop plans by London boroughs to make better food more widely available.
Jamie Oliver has described the plans as a bold step forward for child health in London.
The chef and campaigner said: This is a game-changing moment, protecting kids from relentless junk food advertising on their daily journeys to school and around our amazing city.
Chief Medical Officer, Professor Dame Sally Davies, added: The evidence is clear that although it is not a silver bullet, restricting the amount of junk food adverts children are exposed to will help reduce obesity.
Children are inundated with adverts for unhealthy food so this is a really encouraging move and a bold step in the right direction.