BALTIMORE — Ahead of menu labeling requirements, top restaurant chains have reduced calories in new items, according to research from Johns Hopkins Bloomberg School of Public Health in Baltimore.

The study, published in the American Journal of Preventative Medicine, examined more than 19,000 menu items at 66 of the 100 largest U.S. restaurant chains for 2012 and 2013.

Calories in menu items introduced last year dropped 12%, or by about 56 calories, compared with launches in 2012. New entrees contained 67 fewer calories, new beverages had 26 fewer calories, and children’s items had 46 fewer calories, on average.

The caloric content of core items, however, had not changed from year to year. And at restaurants with a specific menu focus, such as burgers or pizza, the researchers tracked a greater decline among new non-core items like salads.

“Given that federal menu labeling provisions are not yet in effect, the observed declines in newly introduced menu items may be capturing voluntary actions by large chain restaurants to increase the transparency of nutritional information,” the study said.

Thirty-three per cent of children, 41% of adolescents and 36% of adults eat at fast-food restaurants on a typical day, consuming an average intake of 191 calories, 404 calories and 315 calories, respectively, according to the study.

“If the average calories consumed at each visit were reduced by approximately 60 calories (the average decline observed in newly introduced menu items in 2013), the population impact on obesity could be significant,” the researchers wrote. “Of note, however, the caloric content of restaurant meals remains quite high.”