Junk food adverts will be banned on TV before the 9pm watershed with a total ban online, under the Government's new plans.
Boris Johnson has abandoned his opposition to outlawing ads for unhealthy foods, with a new ban included in the Queen's Speech.
Mr Johnson once railed against the 'nanny state' and 'sin taxes', and reportedly said he would "get rid of Jamie Oliver and tell people to eat what they like".
But the Prime Minister's nearly deadly brush with Covid-19 last year appears to have triggered an overhaul in his attitudes to the country's waistlines.
Mr Johnson admitted he had been "too fat" before he was hospitalised with coronavirus, and has since got on a fitness kick.
© Phil HarrisBoris Johnson out for a jog with his dog Dilyn
More than six out of 10 adults and one in three children leaving primary school are overweight or obese, according to official figures..
Obesity is considered a risk factor in people falling seriously ill with coronavirus, as well as other health issues such as type 2 diabetes, heart disease and a number of types of cancer.
The new Health and Care Bill will include a blanket ban on junk food ads online, as well as a curb on TV promotions for unhealthy snacks until after 9pm
'Buy one get one free' and other multi-buy deals on high fat foods and snacks full of sugar and salt will be restricted from next April.
New laws will also force big restaurants and takeaways (with more than 250 staff) to slap calorie labels on the food they sell.
The new bill aims to super-charge efforts to keep people healthy as the country slowly recovers from coronavirus, with a focus on issues like obesity, smoking, air quality and drug abuse.
However it includes little detail on long-promised plans for social care, which Mr Johnson insisted were ready when he became Prime Minister in 2019.
It comes as Mr Johnson unveiled his programme for Government, with 28 new bills to help Britain "build back better" from the Covid pandemic.
However none of the bills include detail on social care or a solid set of changes to fulfil his goal of "levelling up".
The Queen's Speech takes place every parliamentary session, where the monarch reads out the Government's agenda for the next year.