Breakfast cereal portions are depicted as too big as experts say pictures on the side of boxes are unrealistic.

Images of Frosties, Crunchy Nut Cornflakes, Coco Pops, and other UK cereals show bowls “brimming to the top with cereal and milk” and containing as much of 90g of cereal, while their packaging recommends a portion size of just 30g.

“This suggests that if the imagery on the cereal packet is imitated, children aged 4 to 10 would be exceeding their daily limit of free sugars by 12.5% by eating one bowl of cereal,” the study published in the British Dental Journal found.

The study investigated 13 breakfast cereals and analysed the content of the packaging with regard to imagery, health claims and nutritional content.

Several cereals were found to be more than one third sugar by weight.

The investigation also found that even if the manufacturer’s suggested portion size was used 8 of the 13 cereals provided over half of the recommended daily sugar intake for a child between the ages of 4 and 6.