A study carried out by Washington State University (WSU) has found that font size plays and important role on food menus as restaurants can “persuade” customers to choose healthier foods by adjusting the size of numbers attached to nutritional information on menus.

The research was led by Ruiying Cai, an Assistant Professor in the WSU School of Hospitality Business Management, with the study being published in the International Journal of Hospitality Management.

Cai noted that in the US, restaurants with more than 20 locations are already required to show the calorie content of food on their menus. With this in mind, Cai claimed that by representing calorie content values incongruously (using physically larger numbers on the page when they’re attached to lower-calorie options, and smaller numbers for high-calorie foods), Cai said businesses can successfully “nudge” customers toward healthier choices.

“When restaurants use a larger font size for the calorie content of healthy foods, even though the number itself has a smaller value, it will increase consumers’ preference to order the healthier item,” said Cai.

To carry out the research participants were asked to choose between a less healthy item (such as a smoked beef burger) and a healthier option (like a grilled chicken sandwich). They were then randomly assigned to two groups.

In the first group, number values and font size rose and fell together. However, in the second group, the relationship between the numbers’ magnitude and their size was incongruent, meaning the font size became smaller as the number values rose and vice versa.

In addition, the research team also posed questions to gauge how health-conscious participants were and gave varying time limits to some to measure the effect time constraints have on their decisions.

Results of the study revealed that participants in second group, who saw low calorie counts printed in large fonts, were “more likely to lean toward the healthier option”.  What’s more, respondents who indicated they were less health-conscious were also the most affected, particularly when there was a tight timeframe to make the choice.

Meanwhile, participants that had a high level of health awareness were less likely to be swayed, according to Cai, but she noted this is likely to be because they already favoured healthy food.

“Even if you use some of the smart tricks, it does not work as well as for those who are not so knowledgeable about health,” explained Cai.

The study uses a phenomenon called the “numerical Stroop effect,” which uses incongruity to emphasise the lower numbers and slightly slow the decision-making process, to help nudge customers toward healthier menu options.

“Restaurants have an interest in encouraging patrons to make healthier choices. However, simply labelling the food as healthy may not have the intended effect,” continued Cai.

“Healthy food items could be profitable for restaurants, but whenever a ‘healthy’ label is attached, people may assume it does not taste good. We’re trying to provide restaurants with subtle cues, rather than saying it out loud,” Cai concluded.