NHS data shows almost one in 10 (9.2%) reception-aged children are now living with obesity, while one in five children have tooth decay by the age of five.
It is estimated obesity costs the NHS more than £11bn every year.
Evidence shows children’s exposure to ads for unhealthy food can influence what they eat from a young age, in turn putting them at greater risk of becoming overweight or obese.
The government estimates the ad ban will prevent around 20,000 cases of childhood obesity.
Katherine Brown, professor of behaviour change in health at the University of Hertfordshire, said the ban was “long overdue and a move in the right direction”.
She said: “Children are highly susceptible to aggressive marketing of unhealthy foods and exposure to them puts them at greater risk of developing obesity and associated chronic diseases.”
Ms Brown called for the government to make nutritious options “more affordable, accessible and appealing”.
The FDF said manufacturers are “committed to working in partnership with the government and others to help people make healthier choices”.
It added: “Investing in developing healthier products has been a key priority for food and drink manufacturers for many years and as a result, our members’ products now have a third of the salt and sugar and a quarter of the calories than they did ten years ago.”
