The government is to delay a ban on multi-buy deals for junk food and pre-watershed TV advertising.
The Department of Health said the plans would be deferred for a year while officials assessed the impact on household finances as families struggle with the increasing cost of living.
It said curbs on junk food placement in stores would still go ahead in October.
But health campaigners have accused the PM of "playing politics" with children's health.
The Department of Health and Social Care (DHSC) said the planned ban on "buy one get one free" (Bogof) deals for food and drinks high in fat, salt or sugar (HFSS) as well as free refills for soft drinks, would be put on hold for 12 months, until October 2023.
Plans to restrict TV advertising of junk foods before the 21:00 GMT watershed and paid-for online adverts are also being paused for a year and will not come into force until January 2024, the department added.
Laws requiring large restaurants, cafes and takeaways to list calories on their menus came into force last month.
Public health minister Maggie Throup insisted the government remained committed to tackling the issue of childhood obesity.
"Pausing restrictions on deals like 'buy one get one free' will allow us to understand its impact on consumers in light of an unprecedented global economic situation," she added.
However, health campaigners have criticised delays to the plans, and accused Boris Johnson's government of failing to tackle childhood obesity.
Prof Graham MacGregor, a cardiologist at Queen Mary University of London and chairman of Action on Sugar, said the delays contradicted the government's "levelling up" agenda.
"Boris Johnson could have left a legacy of being the first prime minister to address obesity in a meaningful way, particularly in restricting advertising and promotion of unhealthy food which were his flagship policies," he said.
"Instead, he has given in to his own MPs, and an aggressive food industry, who, ironically, were starting to comply with these new policies."
Meanwhile, Barbara Crowther, of the Children's Food Campaign, said ministers should be urgently curbing multi-buy offers instead of "delaying and dithering".
"Obesity is spiking and millions of families can't afford to put proper food on the table. Multi-buy offers make people spend more on junk, and less on healthy food," she said.
"This delay threatens the UK target to halve childhood obesity by 2030. Boris is playing politics with our children's health."
Labour's shadow health minister Andrew Gwynne said: "Instead of cutting childhood obesity, preventing ill-health and easing pressure on the NHS, this chaotic government is performing another U-turn."
The delay was also criticised as "unconservative" by former health minister Lord Bethall, who said it would be "extremely difficult" for the government to come back to the plans before the next election.
Lord Bethell, who previously served in Boris Johnson's government, told BBC Radio 4's Today programme that while he was "pro-choice", illnesses caused by excessive junk food consumption were placing a burden on the NHS and the taxpayer.
But industry body the Food and Drink Federation (FDF) argues that it "makes sense" to delay restrictions on multi-buy deals as families and manufacturers struggle with "high inflation".
Kate Halliwell, the FDF's chief scientific officer, also welcomed the delay to the advertising ban, saying it would give the industry time to prepare for a change in the law.
When the government unveiled the planned curbs, some of the UK's biggest food companies, including Britvic, Kellogg's and Mars, criticised them as "disproportionate" and lacking evidence.
Last month, Kellogg's said it would take the government to court over the curbs preventing some cereals from being placed in key locations in stores due to their high sugar content.
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