Fast food should be banned from buses and trains, as part of efforts to “nudge” the public out of round-the-clock snacking, obesity experts say.

The call for radical restrictions, in an attempt to reset social norms, came amid warnings that “guzzling on the go” is fuelling Britain’s weight problem.

Experts at the world’s largest obesity conference urged politicians to make sweeping changes to limit the availability of junk food on public transport.

They said buses, trains and trams should take action, in the same way that other health threats, like smoking, and alcohol, have been banned.