Plans to ban junk food ads and to stop children buying high-caffeine energy drinks are among radical public health measures being drawn up by ministers to prevent illness and so ease pressure on the NHS.

The government made clear it would face down “predictable cries of ‘nanny state’” because Keir Starmer was convinced this was the way to fix the service.

Junk food advertisements will be banned from television before the 9pm watershed, the government has announced. Online ads for products that are high in fat, salt and sugar will be banned altogether. Both measures, which are intended to help tackle childhood obesity, will come into force in a year’s time.

Plans to ban children from buying high-caffeine energy drinks, which form part of the same public health drive and appeared in Labour’s election manifesto, are expected to be announced next month.

In the coming months, the government plans to introduce a strengthened tobacco and vapes bill, which is likely to extend the indoor ­smoking ban to pub beer gardens.

Ministers are also looking at expanding water fluoridation to improve dental health, and giving councils enhanced powers to block the development of fast food outlets near schools to tackle obesity. Further measures are being looked at, with government officials canvassing the public health sector for policy ideas.

A government source told the Guardian: “We’re looking seriously at where we can go further on prevention. As Ara Darzi set out in his report, rising sickness in our society is putting huge pressures on the NHS. Keir’s not afraid to do controversial things if they’re the right things to do. He’s willing to take on the predictable cries of ‘nanny state’ in order to cut waiting lists, keep people healthy and in work, and secure the long-term future of the NHS.”

Starmer delivered a speech at the King’s Fund after a report by Lord Darzi, a former health minister, concluded that the health service was “in critical condition” after years of neglect by successive governments.

The prime minister said he was prepared to take “much bolder” action on preventing illness. “There’s diet, there’s healthy lifestyle, we are going to have to get into that space. I know some prevention measures will be controversial but I’m prepared to be bold, even in the face of loud opposition,” he said. “Some of our changes won’t be universally popular, we know that, but I will do the right thing for our NHS, our economy and our children.”

Starmer and Wes Streeting, the health secretary, want the NHS to take a more proactive role on prevention, including through the health check programme in workplaces. The programme provides people with checkups at work with a view to preventing heart disease, kidney disease and diabetes.

A public health official said the Darzi report “did not pull any punches” on the wider public health causes behind the NHS’s woes, and that this was reflective of a wider shift in approach from that of the last government.

They said officials had been consulting the sector for policy ideas, including on how to combat obesity. As well as anti-smoking measures and a likely push on water fluoridation, the official said they believed ministers were examining ways to limit the health toll from alcohol. “I don’t know if it will happen, but along with smoking, alcohol is the obvious thing to look at,” they said.

Starmer came under fresh pressure on Friday to be bold on public health from the chef and food campaigner Jamie Oliver, Henry Dimbleby, the architect of Boris Johnson’s food plan, and Anne Longfield, a former children’s commissioner for England.

Oliver urged the prime minister to learn lessons from the success of some of the tough anti-obesity measures that have been implemented internationally, referring to Amsterdam’s education of primary schoolchildren about healthy eating, restrictions on junk food packaging introduced by Mexico and Chile, and Colombia’s sugar and salt taxes.

“Across the world we’re seeing leaders take action, stopping the overwhelming bombardment of junk food advertising and making the healthy choice the easy one. And they’re reaping the rewards. Surely it’s time our government stepped up and followed suit,” Oliver said.

Dimbleby, a co-founder of the Leon restaurant chain who drew up a food strategy for Johnson’s government, advised Starmer to regulate the food industry to force it to make its products healthier.

He said: “If we are to move from treating sickness to preventing it, it is essential that we change the way we eat. Now is the opportunity for the government to introduce policies to ensure that everyone can access the foods needed to keep them healthy, and that the food industry is regulated to stem the relentless flow of junk food that has become a lethal cultural norm.”

Johnson and Rishi Sunak had both promised to ban junk food adverts on TV before 9pm but repeatedly delayed the measure. Dimbleby urged ministers to go further by banning junk food ads in video games, taxing products that contain too much salt or sugar, and forcing manufacturers to disclose each year how much of their sales comes from products that under government guidelines are classified as junk food.

Research by the Food Foundation suggests that bad diet is causing a record amount of disability among people across the UK who are overweight or obese.

The cumulative number of years that people spend contending with a disability linked to them being dangerously overweight rose from 573,266 in 2011 to 755,212 in 2021, the charity found. It estimates that 6,000 lives a year could be saved and 10% of disability avoided if everyone ate 30% more fruit and vegetables, 50% more fibre, 25% fewer fatty, salty and sugary foods and 30% less meat.

Longfield, the former children’s commissioner for England, proposed extending the sugar tax to sugar-sweetened drinks such as milkshakes to help tackle the “staggering” number of children who are getting rotten teeth from eating too many treat foods.

It is one of a series of measures set out in a report by Child of the North, Longfield’s thinktank Centre for Young Lives, and dental experts. They also urged ministers to increase the fluoridation of water, given its proven benefits for dental health.

Also on Thursday, Michael Barber, who was head of the delivery unit in Tony Blair’s government between 2001 and 2005, was appointed Keir Starmer’s adviser on effective delivery.