Hundreds of thousands of children are watching junk food adverts every week while watching family TV shows, health experts have warned.
Adverts shown during prime time family television are promoting sweets, crisps and fast food, experts said.
The Obesity Health Alliance (OHA) has called for a 9pm watershed to protect children from junk food marketing.
It that current guidance is not fit for purpose and is helping to turn the nation's children into "telechubbies".
Experts from the University of Liverpool conducted analysis of adverts shown during intermissions around The Voice, The Simpsons, Hollyoaks, Coronation Street and Ninja Warrior - which are watched by hundreds of thousands of under 16s every week.
They found that more than half of food and drinks adverts shown during these programmes are for products high in fat, sugar and salt.
In one case, researchers observed nine junk food adverts in just 30 minutes.
The research, commissioned by the OHA - a coalition of health charities and medical organisations, used official guidelines to assess whether the adverts would have been allowed to be shown during children's programming.
They concluded that 59% of food and drink adverts would be banned from kids' TV.
Diabetes UK, which is part of the alliance, said that current junk food advertising rules are "failing children and their families".
During an episode of Hollyoaks on E4, watched by an average of 140,000 children during the study period, researchers observed nine junk food adverts in 30 minutes.
Meanwhile, during The Voice, watched by an average of 708,000 children every episode during the study period, 75% of all food and drink adverts shown would likely be banned from children's TV, researchers said.
Health bodies have previously criticised ministers for not introducing more stringent advertising rules during it's Childhood Obesity Plan, published last summer.
The OHA has called for a 9pm watershed and also recommended that brands associated with junk food products should be banned from sponsoring programmes popular with children.
Professor Mary Fewtrell, nutrition lead at the Royal College of Paediatrics and Child Health, said: "This report is another grim reminder why we're losing the fight against the scourge of childhood obesity.
"We know brand recognition influences children's behaviours from as young as 18 months - which is why Government saw it fit to ban junk food advertising during children's shows back in 2010.
"Children are very impressionable and need protection from the hundreds of millions of pounds spent each year on junk food advertising, much of which is within the family viewing hours of 6-9pm."
Caroline Cerny, Obesity Health Alliance lead, added: "The programmes most popular with children are dominated by junk food brands who seem intent on turning us all into telechubbies.
"The Government has laid a foundation with their Childhood Obesity Plan, but now it's time to go further with decisive action to stop children being bombarded with adverts for junk food with a 9pm watershed."
Nikki Joule, Diabetes UK's policy manager, added: "This report makes clear that the current junk food advertising rules are failing children and their families.
"To protect our children's health, and to prevent further costs to our already strained health service, we urgently need the Government to act now and close the loopholes that allow companies to market junk food to children during peak family TV viewing time."
A Government spokesman said: "Current advertising restrictions in the UK on junk food are among the toughest in the world, including a ban on advertising junk food in children's media.
"Alongside this we are delivering the most ambitious childhood obesity plan in the world - taxing sugary drinks, funding research on junk food advertising and cutting sugar and calories in food before it hits shelves and plates.
"But it's very early days tackling a problem decades in the making, and we have not ruled out further action if the right results are not seen."
An ITV spokesman said: "ITV takes its responsibilities in this area very seriously and we work actively to promote healthy lifestyles on screen."