A salad from Olive Garden. (Matt McClain/The Washington Post)

Menus of America, you've been slimming down.

The largest chain restaurants in the United States, including McDonald's and Applebee's, have significantly reduced the calories in their newest items, according to findings published in October's American Journal of Preventive Medicine.

From 2012 to 2013, researchers from the Johns Hopkins Bloomberg School of Public Health analyzed nearly 20,000 menu items from 66 of the 100 largest American chain restaurants using MenuStat project data, a census of menus. They found a nearly 60-calorie average drop (about 12 percent) for new items.

New entrees, children's items and beverages had the biggest decrease in calories.

But overall, average calories didn't change on these menus. And most of the changes were to items that don't make up the core of a restaurant's business; for example, there wasn't much change in burgers at burger joints or pizzas at pizza places.

The voluntary reduction in calories is probably a result of impending federal regulations requiring restaurants to disclose calorie counts, said Sara Bleich, the study's lead author and an associate professor at the Johns Hopkins school. Some localities, such as New York City, already have required restaurants to do that.

"Because these are some of the largest chains in the country, from a revenue perspective, chances are many of them have been impacted by the local regulations. That transparency has pushed them to think more carefully as they introduce new menu items, as they do every year" with fewer calories, she said. "It's just so shocking to consumers when they see these numbers, if they see a salad has 900 calories."

While 60 or 70 calories might not seem like a lot, that drop can have a major impact over the long run, Bleich said. For instance, on an average day, children and adolescents have a 110- to 165-calorie "energy gap," meaning they are overeating and/or under-exercising. "This is a way to chip away at that," Bleich said, noting that about one-third of adults and children eat at fast-food restaurants on a typical day.

Bleich said the reduced calories may even have a bigger impact on American diets than the disclosure of calorie-count information, because labeling items as "healthy" may lead some consumers to skip those items.

"Behavior is very resistant to change," she said. "The beauty of what we're seeing is consumers aren't being made aware of it, that some things they might purchase are just a little bit lower-calorie."

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The Center for Science in the Public Interest's Xtreme Eating Awards went to nine "winning" chain restaurant meals especially high in calories, fat, sugar and salt. The Cheesecake Factory got three of them. (Tom LeGro/The Washington Post)