Already in use in some major British supermarkets, the traffic light system – red, amber and green – reflects high, medium or low levels of fat, sugar and salt.

Under the plans, favourites like the doner kebab with chips will carry red labels as they contain over the double the recommended daily allowance (RDA) of salt and fat, while salads will have a green label, thanks to being low in cholesterol.

Dave Horsfield, principal trading standards officer, explained: “There is no legal restriction on the nutritional content of takeaway food. We didn’t know exactly what was in the food and it was a question that needed to be answered”.

The city’s fat busting tactic was sparked by a survey, by Liverpool trading standards officers that analysed in excess of 300 takeaway meals from across the length and breadth of the city.

On the menu of shame were pizzas, which contained well over twice the RDA of salt and fat in just one slice; another offender was prawn chow mein, containing 350% of the RDA of salt.

But perhaps most disturbing revelation turned out to be that a dish of beef with green peppers, black bean sauce and fried rice contained four and a half times the RDA for salt.

Too much fat can lead to obesity, while excessive salt has been linked to increased blood pressure, leading to strokes and heart attacks.

“The results are quite shocking,” said Beri Turner, a member of the city council’s executive. “I think a lot of people who buy food from takeaways will be horrified to find out just how much salt and fat is combined in just one meal”.

The council intends to provide guidance for Liverpool’s fast food outlets on just how to avoid unhealthy ingredients, and where owners can seek healthier alternatives to include in cooking. “The main point is to reduce fat and salt content without affecting the taste of the meal,” Horsfield said.

Currently, there is no legislation that prevents such meals from being sold. However, takeaways will be able to choose whether to sign up on a voluntary basis. Although there is no legal pressure for takeaways to comply, it is hoped that they will set aside any qualms they have in using the labels in order to take the opportunity of helping to improve the nutrition and well being of their customers.

Liverpool Trading Standards believes that takeaways that agree to the traffic light labelling will actually see business go up because customers will appreciate their honesty and desire to highlight the healthiest choices on the menu.

“There are very good reasons why this is a good idea,” said Dave Heywood, manager of the Hansel and Gretel takeaway in Liverpool. “It will give a good indication of what people are getting for their money”.

A recent Which? survey on food labelling revealed that 90 per cent of participants found the traffic light food labelling system very, or at least, fairly, easy to use, and its introduction has had a dramatic impact on consumer behaviour, boosting health conscious decisions.

The measure has already led to a dramatic fall in sales of red-labelled products and a rise in green-labelled ones in the supermarkets who have voluntarily adopted the scheme.

Indeed, at Sainsbury’s, sales of hot desserts that carry the amber and green grading have soared by 42%, whereas those graded red have dipped by 11%.