The Government has signalled a tougher crackdown on the advertising of junk food to children, just weeks after stricter new rules came into effect.

It has published an updated nutrient profiling model (NPM), which is used to calculate which products fall into the “less healthy” category and the associated restrictions on advertising them to children.

The Department of Health and Social Care (DHSC) said it would carry out a full consultation on applying the new NPM to advertising and supermarket promotion rules.

Stricter rules on the advertising of unhealthy food came into full effect on January 5, preventing ads for food and drink that is high in fat, salt and sugar appearing on television between 5.30am and 9pm, and online at any time.

The current ban applies to products that fall within 13 categories considered to play the most significant role in childhood obesity, including soft drinks, chocolates and sweets, pizzas and ice creams, but also breakfast cereals and porridges, sweetened bread products, and main meals and sandwiches.

Products that fall into these categories are then also assessed as to whether they are “less healthy” based on the NPM, which considers their nutrient levels and whether products are high in saturated fat, salt, or sugar.

Only products that meet both of the two criteria are included in the restrictions.

However, the current NPM, on which the advertising rules are based, is more than 20 years old and considered out of step with current health advice, with the revised model first published in 2018 but shelved by the last government due to concerns about the impact it would have on the food industry.

The new model introduces a lower threshold for free – or added – sugars, plus those naturally present in syrups, honey, and unsweetened fruit and vegetable juices, smoothies, purees and pastes.

This includes more desserts and foods that parents may mistakenly think are healthier options, such as some sweetened breakfast cereals and fruit-flavoured yoghurts marketed to children.

Yoghurts with no added sugar would pass the new NPM, and sausage rolls and fruit juice with no added sugar, for example, are also not in the scope of any updated restrictions.

According to current advice, free sugars should make up no more than 5% of energy intake, but most children are consuming double that and fewer than one in 10 children meet the recommendation, while 90% of children are not consuming enough fibre, the DHSC said.

Early estimates suggested that applying the updated model to the current junk food advertising and supermarket promotion restrictions could reduce childhood obesity cases by an additional 170,000.

A DHSC spokesman said: “Most children are consuming more than twice the recommended amount of free sugars, and more than one in three 11-year-olds are growing up overweight or obese.

“We want to work with the food industry to make sure it is the healthy choices being advertised and not the ‘less healthy’ ones so families have the right information to be able to make the healthy choice.

“We promised to publish the updated model in our 10-year health plan and now we have done so.

“We want to work with parents and the food and drinks industry to help create the healthiest generation of children ever.”

Karen Betts, chief executive of the Food and Drink Federation, said: “Food and drink manufacturers have made multimillion-pound investments to meet the nutrient profile model that underpins the new promotion and advertising restrictions, the latest of which only came into force in this month.

“This includes developing new options that make it easier for consumers to swap to healthier choices.

“We have serious concerns that changing to the new model will mean many healthier options could no longer be promoted or advertised to consumers, which runs the risk of them being delisted by retailers.

“It also undermines investment decisions that businesses thought they were making in the longer term, and the uncertainty is causing companies to pause investment in developing healthier products.

“We urge Government to meet industry as soon as possible to discuss our concerns and how we can work together to help shift consumers towards healthier diets.”

Andrea Martinez-Inchausti, assistant director of food at the British Retail Consortium, said: “Retailers are concerned about various aspects of the new NPM.

“Re-categorising many nutrient dense products such as yoghurts, smoothies and breakfast cereals as unhealthy, risks unintended consequences. There are also significant operational challenges in accurately calculating the level of free sugars in products.

“We need to see greater clarity on the proposals, and it is critical that these plans align with retailers’ reformulation work, or else they risk bringing reformulation to a halt.”