Child obesity due to poor nutrition and lack of exercise is a "ticking timebomb" for life expectancy levels, the UK's food watchdog has warned.
Advertising influences children's eating habits, the FSA has found
The Food Standards Agency (FSA) chairman, Sir John Krebs, said the trend meant young people today would live less long than their parents - the first reduction in more than a century.
Sir John, in an interview with the Observer newspaper, called for changes to food marketing and an end to celebrity endorsements of unhealthy meals and snacks.
"What we are faced with is a situation where, if nothing is done to stop the trend, for the first time in a 100 years life expectancy will actually go down," he told the newspaper.
"[That] is an extraordinary reversal of the general gains in health.
"We're all looking forward to a longer and healthier old age, and that trend could be reversed."
The FSA, whose own research shows advertising influences children's eating habits, wants some food packaging to carry health warnings.
It is concerned that popular entertainers and cartoon characters are promoting foods that contain dangerously high levels of fat or salt.
A discussion paper has been launched to look at possibilities for improving the promotion of foods that could improve children's diets and health.
The agency, the government food watchdog, will decide next year, following public debate, which policy options to recommend to the government.
The agency's concerns echo those of Labour MP Debra Shipley, who last week called for advertisements that promote food and drink high in fat, salt and sugar to be banned from children's television.
She said the images of burgers, biscuits, crisps and fizzy drinks can only contribute to the onset of obesity in later life.
Allowing the adverts to appear between programmes watched by the under-fives counters the government's efforts to encourage healthy eating, she says.
Ms Shipley's Children's Television (Advertising) Bill would outlaw advertising during pre-school children's TV programmes that feature food and drink high in fat, salt and sugar.
Ms Shipley, responsible for the Protection of Children Act 1999, is supported by more than 100 MPs and 90 national organisations, including the National Heart Forum, Women's Institute, Food Commission, National Union of Teachers and National Consumer Council.