Displaying the calorie content of meals in canteens and restaurants could significantly reduce weight-gain in customers, a new study shows.

Researchers conducting the first long-term study of the effects of labeling meals in a university’s students’ residence canteen over the course of two 36-week academic years found students had reduced weight gain by an average of 3.5kg.

Charoula Konstantia Nikolaou, a Phd student who led the study at the University of Glasgow, said: “Calorie labeling helps people understand what’s in their food, and makes them aware of lower calorie options.

In one year, the university dining room – where students’ breakfast and dinner were included in their accommodation charge – displayed calorie information for main meals for a pilot period of five out of 36 weeks, and in a second year, calorie information was displayed on large colorful cards for all main meals for 30 out of the 36 weeks.

During the first year students gained an average of 7.7 pounds (3.5 kg). In the second year, students maintained their average initial weight, unchanged. Students studying at the same university but not living in the halls of residence gained an average of 1.8kg during the first year and 2.1kg in the second year.

Ms Nikolaou said: “Previous literature has shown little or no benefit from calorie labeling, however that research did not look at long-term exposure, and in those studies most consumers did not notice the calorie labels.   “We were glad to see that exposure to our very prominent calorie labeling for an entire school year did not just reduce weight gain in these students, but eliminated it altogether for the group. This is especially important because young adults are vulnerable to weight gain, which often leads to obesity later in life.”

Most students surveyed in year two reported using the calorie labeling for weight control and healthier eating, and overall they ordered meals with 18% fewer calories than in year one. These meals had less fat, saturated fat and frying oils than meals ordered in year one, and there was no decline in micronutrient consumptions in year two. 

Recent guidance from the United Kingdom’s Responsibility Deal and the United States’ Affordable Care Act encourage calorie labeling in chain restaurants, yet there have been mixed results as to the effects of calorie labeling on consumers’ meal choices and weight status.

This new research shows that consistent exposure to prominent calorie labeling of main meals reduced the likelihood of young adults gaining any weight over a one-year period by 50%.   Nikolaou’s PhD research was supervised by Dr Catherine Hankey and Professor Mike Lean, who said labelling represented a very low-cost, transferable intervention that proved effective.

Professor Lean said: “The caterers were impressed with the effectiveness of tactic as well, because their spending on food ingredients was lowered by 33% during the year with calorie labeling.”

This lower cost of ingredients offsets what caterers and food companies often argue: that healthier ingredients are more costly. 

Sara Bleich, Associate Professor at Johns Hopkins Bloomberg School of Public Health speaking on behalf of The Obesity Society, said: “Although the policy is encouraged in the US and UK for large chain restaurants to present caloric content for menu items, this study reminds us that there isn’t any legislature for cafeterias at universities, schools or workplaces to display this type of information.

“The sooner policymakers better understand these associations between calorie labeling and weight loss, the closer we will all be to making better food choices.”

The study is one of six papers selected by the editors of the journal Obesity to be highlighted in the 2nd Annual Obesity Journal Symposium at ObesityWeek 2014.

The research paper from the study will be published in a special section of the November 2014 issue of Obesity. 

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Media enquiries: stuart.forsyth@glasgow.ac.uk / +44 141 3304831 or Chelsea Clark  cclark@obesity.org

First published: 6 November 2014