LAS VEGAS—Moviegoing is most associated with one dietary indulgence: buttery popcorn, served up by a bored teenager filling tub after tub.

Now, some entrepreneurs want to fit the entire food pyramid into the multiplex. “Edamame is the answer,” said Ron Law, whose product, EdaMovie, is sold in eight theater chains.

“What people really want is something fun, something lighthearted,” said Dr. Law, a former cardiologist based in Denver who calls the protein-rich legume “nature’s original finger food.” His soybeans are fighting for movie-theater market share with more than just Reese’s Pieces. Theaters must now lure gourmands with options that include shrimp cavatappi at AMC theaters; quinoa and almond crusted goat cheese salad at iPic locations or spicy sushi lobster roll at Cinépolis sites.

And a surge in dine-in movie theaters—equipped with full kitchens and ushers who double as waiters—has spurred a rethink of the concession stand itself. The expanding menus are important to the bottom line: Major chains say tens of millions of moviegoers buy tickets but forgo food and drinks, which are highly profitable.

The candy-counter overhaul was on display last month at CinemaCon, an annual convention for movie-theater operators held at Caesars Palace. On the trade-show floor, among the wall-paneling providers and aisle-lighting firms, were samples of Oreo-flavored churros, smoky bacon cheddar dipping sauce for soft pretzels or chips and Popcornopolis, creators of an organic popcorn blend the company said comes with “better for you” flavors.

Many of the newer items are lower-fat alternatives to the traditional tray of nachos doused in cheese, and additions that might come with a learning curve, said Bruce Coleman, an executive vice president at Brenden Theatres, a 90-screen circuit across California and the Southwest. He was nibbling on one of Dr. Law’s edamame samples and said he now gets questions from patrons like, Do you have vitamin water? And what kind of oil was the popcorn popped in?

Movie-theater executives say consumers want the healthier options, and theaters are getting ready for a December requirement by the Food and Drug Administration for most of them to list calorie counts.

Not even popcorn is safe from tinkering. Dave Waldman’s Kickers Powdered Fruit Blends are sweeteners he said can make even the stalest popcorn taste exotic. “There are really no fruit-based toppings for popcorn out there,” said Mr. Waldman, who lives in Charlotte, N.C.

The entrepreneur, a former top competitor in the Mr. America bodybuilding competition, said the chocolate peanut butter banana flavor complements popcorn the best—although there are other uses. He said some clients have told him they sprinkle the apple cinnamon Kickers on their children’s broccoli, and he puts maple banana cream in his morning coffee.

AMC Entertainment Holdings Inc., the nation’s second-largest chain, operates 18 dine-in theaters—part of a plan to consolidate dinner and a movie into one location. AMC’s most popular, located in Menlo Park, N.J., can serve more than 4,000 plates on a Saturday, said Jennifer Douglass, an AMC executive who oversees the chain’s dining operations. Top sellers include the Southwest fajita wrap and bistro mac & cheese.

The ventures require some creative thinking at AMC. Ushers are recast as “server ninjas” who deliver food inconspicuously while a movie is running—and checks before the credits roll. Silverware can’t be noisy. And hand-held options like lettuce cups work better than, say, a wedge salad for dining in the dark.

“We’re not going to do soups,” said Ms. Douglass.

Mike Truesdale can appreciate that. He left a recent Saturday afternoon screening of “Avengers: Age of Ultron” at an MGN Five Star Cinema in Glendale, Calif., with grease stains on his T-shirt from a Margherita pizza. “I get it on me. I can find it. I’ll eat it off my shirt,” he said. His companion, Anita LaBonte, said she opted for the pizza because it seemed easier to eat in the dark while wearing 3-D glasses.

Still, Mr. Truesdale didn’t seem deterred from the dine-in experience, which he called “first class.” “We just had a bucket of Champagne. Where can you get that?” he said.

Executives agree theater food, while elaborate, still has to be easy to eat—even sandwiches can be dicey since they typically require two hands.

Enter Uncle John’s Burger Dog. A long, skinny hybrid meat of beef, pork, bacon and cheese, the Burger Dog is now sold in about 75 traditional and drive-in theaters, said its inventors, Christopher Mihm and Tim Braun. It has the elements of a hamburger, molded into the shape of an easily edible hot dog.

Mr. Mihm, a Minneapolis-based director of low-budget horror movies, designed the Burger Dog off a family recipe—initially creating only the concept and the Burger Dog character to use in a scene of his 2013 feature “The Giant Spider.” When Mr. Braun, a marketing executive, saw the Burger Dog—with its top hat-wearing cartoon pitchman and “Eat Me” catchphrase—he told Mr. Mihm they should try to sell it for real. “I know a butcher,” he said.

They hope to expand to nearly 500 locations this year. Part of their pitch to theaters: free help with the marketing. “We bring in a dancing, anthropomorphic Burger Dog who can high-five your kids,” said Mr. Mihm.

All of the new food has helped build a cottage industry in technology to help patrons order. A Grand Rapids company called Concessions on Demand was selling display screens theaters can embed into armrests so moviegoers can order from their loungers.

But there are some housekeeping issues to consider. Patrons in the plush recliner seats readily drop food on the floor, and when the leg rests close the bits are swept under the seats. “It’s like a Hungry Hungry Hippo,” said Edwin Snell of Dolphin Seating, a New Mexico firm. That is why he put a $350 chair model called “The Aristocrat” front-and-center at his CinemaCon display. It comes with a movable leg rest that lifts up for vacuums and mops to fit underneath. Given the growing menus at theaters, he said, “there could be a piece of steak under there.”

Write to Erich Schwartzel at erich.schwartzel@wsj.com

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