A traffic light diagram which details the product's nutritional information is the best way to help consumers make healthier food choices, according to Which?.

Sue Davis, chief policy advisor for the consumer watchdog, said that many consumers tend to be in a rush when they shop and as such a label that is easy to understand at a glance is more useful than one which requires mental arithmetic.

"Our research has shown that consumers find the straightforward multiple traffic light scheme the easiest to use and this could at least ensure that the traffic light colours were used wherever you shopped," she added.

The traffic light labelling system was introduced by the Food Standards Agency (FSA) and shows consumers the levels of fat, saturated fat, salt and sugars in a product.

A red light indicates that the item is high in something the FSA states people should be cutting down on, while green lights are a healthier choice.