People order less and consume fewer calories when information on the calorie content of their food is included on menus, new Irish research has established.

But the extent to which they cut their consumption depends on where the calorie information is shown, according to a study by the Economic and Social Research Institute (ESRI).

It found that consumers given a menu where the calorie information was displayed just to the right of the price, in the same font and size, ordered 19 per cent fewer calories and ate 37 per cent fewer calories.

This was the first scientific study to track consumers’ eye movement using an infrared camera as they read the menu, according to the ESRI’s behavioural research unit.

One-third of the 142 consumers in the study were given a menu with no calorie information, one-third saw a menu with calorie labels placed between the description of the food and the price, and for one-third this information was placed to the right, after the price. Everything else on the menus was identical.

Consumers given a menu with calorie labels placed to the right looked more at the labels. When asked later, they were also more likely to know how many calories were in the lunch.

Critics of calorie posting have suggested it might make diners less likely to enjoy their food, but the study found no evidence of this. Diners shown calorie information rated their satisfaction with lunch at least as highly as those not shown the calories.

Consumer behaviour

“Our results show not only that calorie posting changes behaviour, but also that seemingly small changes to the format influence how well people understand and respond to the information,” said lead researcher Dr Deirdre Robertson of the ESRI. “As nothing else differed, we can be confident that the differences we found in consumer behaviour are due to the position of the calorie information on the menu.”

Experiments of this type can be used to pre-test policies before they are implemented, she said.

In 2015, the then government decided to bring in legislation requiring calorie information on menus after a voluntary scheme was widely ignored by food businesses. Progress has been slow but Minister for Health Simon Harris has promised to publish the legislation by the end of this year.