Nutrition labels which show how much exercise is needed to burn off calories in a food item may help deter people from making unhealthy purchases, a study has found.

The study of 220 people by the University of Canterbury used muesli bars and chocolate bars with different types of food labels to test how people reacted to nutritional information and the effect it had on their exercise choice.

The study, carried out by marketing student Michelle Bouton for her honours dissertation found labels with only calories had little or no impact on people's behaviour or their intention to exercise.

However, when labels converted the calories into an exercise quotient, participant response was markedly different.


Statements like 'you will need to jog for 40 minutes to burn off the calories in this chocolate bar' changed how people perceived a food item, Ms Bouton said.

Not only were people more likely to exercise when they saw such labels, they also felt more guilty, Ms Bouton said.

"My findings showed that the exercise labelling was significantly more effective in both chocolate and healthier muesli bars in encouraging consumers to exercise after consumption.

"It increased the likelihood of having higher feelings of guilt after consumption and was more likely to stop [the participant] consuming the chocolate bar with the exercise labelling."

Labels on muesli bars used in the study said 20 minutes of light jogging would be required to burn off its calories.

The label on the chocolate bars said 40 minutes of light jogging would be needed.

Findings also found people struggled to understand labels on food items.

"Eighty per cent of participants wished that nutritional food labelling was easier to understand and 55 per cent said they had no idea what 1700kj was in calories," Ms Bouton said.

"From these findings it is evident that many consumers are lacking knowledge on how to read nutritional information correctly, and they would like to have a labelling system that is easier to understand."

Recent Australian research into fast-food menu boards also found people were more likely eat 10 per cent fewer calories if outlets listed the energy content of an item on their menus.

Healthy Food Guide nutritionist Claire Turnbull said there was no clearcut solution to food labelling.

"There's huge amounts of research and money...going into trying to find a good solution to food labelling in this country.

"It [exercise labelling] can potentially be quite helpful because at least people can understand what a 20 minute walk is and what a 50 minute walk is."

But, exercise labelling could oversimplify nutritional information, Mrs Turnbull warned.

"The problem again is it depends on how heavy you are, whether you're a man or a woman [and] how walk.

"It still doesn't tell you how much fat is in the product."

"For example, a teaspoon of peanut butter is going to take you longer to burn off than a teaspoon of jam because...peanuts are higher in fat and energy."

However, jam was not a healthier option than peanut butter, Mrs Turnbull said.

"They're just different products."

The University of Canterbury study also provided insight into why people read food labels.

Of the three-quarters of the study group who read nutrition labels, 23 per cent said it was because they were weight conscious and 36 per cent said it was because they were health conscious.