Mayor of London Sadiq Khan has confirmed he is pressing ahead with a ban on junk food advertising across the capital's transport network in an effort to contain a spiralling obesity epidemic – despite claims by the Advertising Association that there is fat chance that the ban will achieve the desired effect.

The outright ban on all high calorie, salt and sugar food and drink promotions will take place from 25 February, signalling the death knell for posters advertising the pleasures of burgers, chocolate bars and fizzy juice.

Restaurant and snack brands will instead be invited to promote healthier alternatives such as unsalted nuts, raisins and sugar-free drinks in an effort to bring bulging waistlines under control.

Commenting on the measure Khan said: “It’s clear that advertising plays a huge part in the choices we make, whether we realise it or not, and Londoners have shown overwhelming support for a ban on adverts for junk food and drink on our transport network.”

It has been estimated that a junk food advertising ban could cost TfL up to £13.3m per year in lost revenue as advertisers flee, undermining efforts to reduce a yawning operating deficit.

Sadiq Khan has previously banned ‘body shaming’ ads on the tube and bus network while TfL has derailed a ‘provocative’ French campaign to lure British businesses to France following Brexit and helped preserve Gary Lineker's dignity by banning a nude crisp campaign starring the broadcaster.

The Advertising Association's chief executive Stephen Woodford argued there was "no clear evidence" that the ban would solve the problem.

He said: "We all want to see rates of childhood obesity dropping but believe there are far better ways to achieve this goal.

Meanwhile, James Barge, director of public policy ISBA suggested that while the mayor "is right to have a focus on tackling the issue of child obesity" it was "disappointed" that the announcement "appears to create a disincentive to companies reformulating their products, creates contractual uncertainty for advertising taken out beyond February and creates regulatory confusion when it comes to brand and creative content."

"We welcome the ability to discuss these proposals further in December and would urge the mayor to convene a working group to ensure that this announcement delivers on the promise of tackling childhood obesity. We stand ready to play our part," he said.