Lidl GB's chief executive, Ryan McDonnell, has voiced worries over the "a lot of uncertainty" surrounding this year's festive advertisements due to fresh restrictions on product displays.
The new regulations state that pre-9pm watershed television adverts cannot showcase products high in fat, sugar or salt (HFSS), which are also entirely prohibited from paid-for online advertising.
Initially scheduled to take effect from October 1, these restrictions have been voluntarily embraced by the industry from the same date, as the government delayed their introduction until next year.
This means a variety of products typically showcased in supermarket Christmas adverts will be missing from prime-time television slots, with companies' own websites and social platforms potentially being among the few places they can be displayed online, the Grocer reported.
Nevertheless, how these regulations will be implemented remains unclear, according to McDonnell, reports the Mirror.
Speaking to The Grocer, he said: "It would be an understatement to tell you that we're obviously learning very quickly, and there's a lot of uncertainty around what the rules of play are, and that's across traditional media and social".
He added: "There's no doubt we've had to engineer our ads differently and be a lot more conservative, because there are so many products and categories that fall under HFSS regulation. So, it's going to be interesting.
"Obviously, with Christmas upon us and retailers increasing their media spend, we're going to have to see how the market plays out. There will be some interesting learnings."
Bakery items including crumpets, scones, croissants, pains au chocolat, pancakes, and waffles are all deemed junk food under the legislation. Sweet treats including muffins, flapjacks, and mini rolls face prohibition, though icing and cake decorations remain exempt, alongside savoury bread and conventional loaves.
The restrictions encompass sugary breakfast cereals including granola, muesli and "porridge oats, including instant porridge and other hot oat-based cereals", whilst snacks including protein bars, cereal bars, and biscuits will also fall under the prohibition.
Food and drink advertisements face bans if products are categorised as "less healthy" through a Government scoring mechanism based on salt, fat, sugar, and protein levels.
In reality, this allows scope for healthier variants of products to remain advertised, such as porridge oats, but excludes items like porridge products enhanced with added sugar, salt, or fat.
Likewise, natural unsweetened yoghurt escapes the ban, whilst fruity and low-fat yoghurt, or fromage frais, will not. Included in the list alongside clearly unhealthy fizzy drinks such as lemonades, colas, and energy drinks are others with added sugar including certain fruit juices and smoothies, milk-based beverages and milk substitute drinks like soya, almond, oat, hemp, hazelnut or rice.
This will also apply to chickpea or lentil-based crisps, fried, flavoured or seasoned chickpeas, seaweed-based snacks and Bombay mix.
The prohibition was enforced from October this year, after which television adverts for junk food products will only be permitted after 9pm.
This will also encompass a ban on paid-for online advertisements for these products to minimise children's exposure to foods high in fat, sugar or salt. The Government has stated it will prevent an estimated 20,000 cases of childhood obesity, and is anticipated to eliminate 7.2 billion calories annually from UK children's diets.
Its impact assessment highlights that "overall the studies do find a clear link between food advertising and calorie consumption".