A Cornell study of food labels in dining halls shows that when people know the calories and fat content in foods, they lean toward healthier fare.

Despite municipal and federal legislation in the pipelines for large restaurants and dining facilities to put labels on their foods, there was very little hard data to show such labels are effective in helping people make healthier food choices, until now.

The study, published in the journal Appetite in April, is important because obesity and related diseases, such as diabetes and hypertension, are steadily rising in the United States. According to recent estimates, 33 percent of U.S. adults are overweight, 35.7 percent are obese and 6.3 percent are extremely obese. Furthermore, the increase in U.S. body weight since the late 1970s parallels an increase in consumption of food away from home.

"Our study is one of the few definitive studies demonstrating, at least in a university dining hall, that putting calories and fat content on the label on various foods purchased in the dining hall produces a reduction in calories and fat content purchased," said David Levitsky, professor of nutritional sciences and a co-author of the paper.

Cornell Dining shared data on food purchases in most Cornell dining halls. The data spanned three semesters before and three semesters after food labels were introduced on individual food servings. Labels included calories, fat and nutrient content. Labeled foods also were categorized high-calorie, low-calorie, high-fat and low-fat. The researchers analyzed how food choices changed after the introduction of labels.

The results revealed a 7 percent reduction of mean total calories and total fat purchased per week. Also, the percent of sales of low-fat and low-calories foods increased, while sales of high-calorie and high-fat foods decreased.

"The reason we found an effect is we had a tremendous amount of data," Levitsky said. "It's a small but significant effect."

The findings support a theory that suggests U.S. weight gain has occurred slowly with gradual increases in daily caloric intake, Levitsky said. Meanwhile, this study demonstrates that small nudges can actually help reduce caloric intake, he said.

"In this 'obesogenic' world, the consumer needs all the help they can get to resist the temptations that the food industry uses to have us increase consumption," Levitsky said. "Insisting that food labels be visible on the foods we purchase may be the kind of help people need to resist the epidemic of obesity."

Catherine Cioffi, now a contractor at PepsiCo., is the paper's first author.