Yet campaigns tempting youngsters to eat a McDonald’s McFlurry Crunchie, a McChicken Sandwich, six chicken nuggets and even the English muffin with butter would sail through a healthy-eating formula devised by the Food Standards Agency and could appear on teatime and Saturday morning television.

The agency published guidelines yesterday on how to identify junk food and drink. They have been drawn up to help Ofcom, the communications regulator, to decide how it intends to help children to choose healthy diets. Ofcom has already ruled out a ban on junk food advertisements, but options include restrictions before the traditional 9pm watershed and compulsory “red light” warnings about products with high salt, fat and sugar content.

Manufacturers, supermarkets and consumer groups have eight weeks to study the formula devised by the agency and pass on their comments. A decision will be made next year.

Under the formula, any food with more than four points and any drink with more than one point per 100 grams is deemed less healthy.

The agency said: “The model utilises a simple scoring system that rates the overall balance of nutrients in the food. This means that the model identifies foods that are high in fat, salt or sugar but recognises the importance of fruit and vegetables, cereal, meat and dairy-based products in the diet.”

Yet calculations by The Times from nutritional information for products on websites for Kellogg’s and McDonald’s, using the agency’s guidelines, showed some curious results. People have bought Special K for years to keep fit and stay slim. Yet using nutritional figures supplied by the companies, Special K scored 10 points and All Bran 8.

Under the formula, a McFlurry Crunchie scored 1 point, a McChicken sandwich 3 points, six Chicken McNuggets 2 points, and the English muffin with butter 2 points.

However, most burgers, crisps and chocolate bars would fail the points test, and advertisements for many products by Walkers, Cadbury-Schweppes, McDonald’s, Burger King and Nestlé would have to be shown late.

According to the agency’s calculations, among the category of least healthy foods were cornflakes, with 10 points, honey and nut cornflakes (14), takeaway chicken nuggets (6), a packet of crisps (16), white chocolate (18), colas (2) and a BLT white bread sandwich (5). They did not give brand names for these products.

Items given a clean bill of health were Shredded Wheat (-6), Ready Brek (-5) and Weetabix (-3), which were all named by the agency. Other healthy options include strawberries (-5), low fat fruit yoghurt (0), takeaway pizza with fish topping (-3), grilled chicken breast (-4), lean roast lamb (0) and lean roast beef topside (-1).

Industry members are ready for a fight. Martin Paterson, deputy director-general of the Food and Drink Federation, said: “It remains the industry’s position that simplistic schemes which demonise individual foods are divorced from the reality of consumers’ lives.”

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