Children need to be protected from pervasive junk food adverts in apps, social media and video blogs, the World Health Organization says.
Its report warns parents are often unaware of the sheer volume of such adverts as they are precisely targeting children.
The WHO also criticized governments for failing to keep up with a revolution in the way people consume media.
Children’s doctors said strict measures were needed to stop childhood obesity.
The report attacked the way some video bloggers vloggers get paid by junk food retailers to promote their food.
It quotes a US analysis that suggests vloggers are now more influential at promoting brands than film or TV because of perceived authenticity.
It also raised concern about the way fast food chains encourage kids through their doors by making restaurants important locations in augmented reality games like Pokemon Go.
And said data on children – their age, location, likes and preferences were being collected to target them with junk food adverts.
Dr Joao Breda, the WHO programme manager for nutrition, physical activity and obesity, told the BBC News website: “It is going digital very strongly and we know that existing models of regulation have holes and gaps that don’t cover the needs of our children.