Restaurants seeking engagement with their Facebook fans are most likely to achieve their goals by asking customers to offer their opinions, according to new research from Expion.

The consulting and social-media software provider perused all the Facebook posts made over the summer by the 50 most well-liked restaurant brands to determine which messages elicited the most comments from Facebook users. By a vast majority, open-ended posts asking people to answer questions or give feedback provoked more responses than posts in which a brand merely touts a new menu item or promotion, Expion found.

The approach a restaurant takes on Facebook should depend on where that brand is in its social-media lifecycle, Mike Heffring, chief strategy officer for Raleigh, N.C.-based Expion, said.

While promotional posts usually don’t get the level of response seen for more engagement-oriented messages, he said, they typically are the tools for building a restaurant’s fan base. But he suggested asking for feedback — along the lines of “What’s your favorite thing about this brand?” — as that roster of fans grows.

“The first thing for me would probably be to do something promotional, because you know what works with that already,” Heffring said. “Then I’d get people to talk more about what they like about your brand, be it the menu or the atmosphere or whatever.”

EARLIER: Study: Technophile Millennials eager to interact in digital domain

Expion’s study of the most engaging Facebook posts was limited to the 50 restaurant brands with the most Facebook “likes.” Between June 1 and Aug. 31, those 50 chains made more than 3,600 posts on Facebook.

To compile its rankings, Expion tracked only the number of comments — “likes” for individual posts were not counted — each message received.