TV and online junk food advertisements could be banned before 9:00 pm as part of the government's plans to combat the "epidemic" of childhood obesity.
Plans for the new watershed have been published for public consultation in an effort to combat the growing crisis, the Department of Health and Social Care (DHSC) said.
One child in three leaves primary school overweight or obese and the number of children classified as severely obese is at a record level, he added.
On Sunday, Labor deputy leader Tom Watson attacked the promotion of the fast food chain's "Monopoly" as a "grotesque marketing maneuver" which, according to him, encourages overeating, labeling it as a "danger to the public health "on Twitter.
Mr. Watson wrote to McDonald's UK asking for the contest to be canceled, which should begin on Wednesday.
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The letter states: "It is unacceptable that this campaign is intended to manipulate families in ordering junk food more frequently and in larger portions, in the weak hope of winning a vacation, a car or a prize in money that they would otherwise have difficulty allowing ", the Observer reported.
Activists, doctors and politicians welcomed the announcement on the proposed ban on advertising.
Television chef Jamie Oliver said: "If we do not find effective ways to improve the health of our children, children in the UK will live a shorter life than their parents.
"It is a fact that children are hugely influenced by junk food ads – so the media and the food industry have a real opportunity here to do something about it."
The ads for foods high in fat, sugar and salt will be consulted on, with the pre-9pm ban being proposed covering TV shows, online streaming sites and social media companies, DHSC said.
Junk food commercials for children's television programs have been banned since 2007, but the broadcast research firm Ofcom said that young people spend 64% of TV viewing time watching programs not specifically targeted at them .
Public Health Minister Steve Brine said: "The NHS is already preparing to treat more and more children due to the severe effects of extreme obesity in the future, so we have a duty to address the underlying causes because we passionately believe in our NHS ".
Up to 1,000 other children are expected to treat severe obesity-related problems such as diabetes and asthma by 2022-23, according to DHSC.
In the past he defined the current situation as a "growing epidemic in childhood obesity".
Professor Russell Viner, president of the Royal College of Pediatrics and Child Health, said he wanted the watershed to be "implemented as soon as possible".
The leader of the joint green party, Caroline Lucas, said: "This is the first generation of children who will live a shorter life than their parents."
The best companies for crunchy, sweet and sugary drinks spend 143 million pounds a year in the UK for advertising compared to just 5 million pounds spent annually by the government for its healthy food campaigns, according to Obesity Health Alliance.
Caroline Cerny, of the organization, said: "The evidence is clear: junk food advertisements have an impact on children's health and current regulations are obsolete and full of loopholes".
The proposed ban will not affect ads for staple foods such as butter, olive oil or meat.
Cancer Research UK is among the bodies calling for the new watershed.
Watching an extra junk food ad per week, beyond the average of six, leads children to consume 18,000 more calories a year, declared the organization last year.
The study estimated that the additional calories are the equivalent of around 70 Mars bars or 60 cheeseburgers – and could amount to a weight gain of 5 pounds (2.3 kg) per year.
A spokesperson for McDonald's UK said: "This year's Monopoly campaign sees customers receiving award labels on carrot, salad and our Big Flavor Wraps range and we removed the incentive to "grow up" by providing the same number of award labels and chances to win on an average meal as you get on a big one.
"The nutritional information is clearly displayed online, in our app, in the restaurant and through our packaging and we continue to review, refine and reformulate our menu to reduce saturated fat, salt and sugar."