Rebecca Alexander’s worst experience dining while large happened just after she nailed a promotion at a nonprofit organization.

She took her staff and her new boss to lunch at a promising downtown restaurant in Portland, Ore., where she lives. As the hostess led the group to a booth, Alexander, who wears a size 30, knew in an instant there was no way she was going to squeeze into it.

“I remember having this out-of-body experience,” she said. “I watched myself sit down and try to get in even though I knew the space was too small, because I so needed it to fit.” Defeated, she asked for a table. The hostess told her there would be a half-hour wait.

“The cherry on top was that I got to be the reason we had to stand around for 30 minutes,” she said.

For people who identify as large, plus-size or fat, dining out can be a social and physical minefield. Chairs with arms or impossibly small seats leave marks and bruises. Meals are spent in pain, or filled with worry that a flimsy chair might collapse.

Deciding where to eat is a challenge. Diners often comb through endless photographs of restaurant food online, hoping someone has posted an image of the chairs or the space between tables.

Even with the best preparation, there is no way to account for a well-meaning manager who doesn’t want to call attention to a diner’s size by asking which seat might be most comfortable.

“Restaurants want to be able to serve large-bodied people, but I think they don’t know they have inadvertently created environments that are difficult for us,” Alexander said.

BRUCE STURGELL, who founded the culture and clothing website Chubstr in 2011, said he walks into every restaurant expecting to be uncomfortable.

“We’re in the early stages of this movement about fat acceptance and body positivity, and you’re seeing it in fashion and on television but not so much in restaurants,” he said.

Some restaurants are gracefully adept at accommodating extremely large customers. “The trick is to not let them know a thing while we scramble like fools to figure it out,” said Ti Adelaide Martin, whose family owns Commander’s Palace in New Orleans.

But that kind of awareness appears rare, even though the national girth has been growing for decades. About 40 percent of Americans over age 20 were classified as obese in a 2017 report by the Centers for Disease Control and Prevention.

“We are in a great cultural moment where people are talking about equity and inclusion, and size falls into that,” said Cheryl Durst, chief executive of the International Interior Design Association.

Design that considers the physical attributes of the people who use a space, as well as how they use it, is fast becoming popular. Size, though, is not always considered.

“The good news is that people are thinking about it sooner, as opposed to retrofitting after the fact,” she said. “But is it top of mind? No.”

TO HELP fill the gap, Alexander introduced a crowdsourced mobile app last year called AllGo, which is a bit like Yelp for plus-size people. “Our reviews are straight from the source,” its website explains. “Fat people who’ve been there before and want to share what it was like.”

The app, which is being tested in Portland, allows people to review places like restaurants, theaters and gyms based on aisle width, seating, bathroom size and other issues important to large-bodied people.

The company raised more than $55,000 through a Kickstarter campaign, and has plans to expand to other cities. Eventually, it will ask reviewers to add their jean size to help users better assess each rating. What works for someone who weighs 250 pounds may not for someone who weighs 400.

AllGo has several high-profile backers, including Tess Holliday, a plus-size model; and Roxane Gay, the author of “Hunger,” which explores in intimate detail what it feels like to walk through the world as a 6-foot- 3-inch woman who at one time weighed more than 500 pounds.

Discussing strategies to help bigger customers is something many restaurants are loath to do, either because they have no plan or because they don’t want to link their food with obesity.

Waffle House, a 2,100-unit restaurant chain based in Georgia that has been criticized for its calorie-heavy menu, offers mostly booths and fixed counter seating. But it also provides larger diners free-standing chairs at counters and tables.

The company would not discuss those decisions.

MANY CHAINS have added movable furniture, wider booths and chairs that meet industry standards for people who weigh as much as 400 pounds. Some accommodations are made to satisfy requirements laid out in the Americans with Disabilities Act, not specifically for larger customers. Courts have held that obesity constitutes a disability under some circumstances, but it remains an emerging area of law.

In 1994, under pressure from the National Association to Advance Fat Acceptance, Denny’s agreed to provide seating specifically designed for large people. In 2011, a 290-pound stockbroker sued White Castle, which he said had violated his rights under the disabilities act because he couldn’t fit into its booths. The company added free-standing chairs, and the suit was dropped.

“We haven’t really had much success in doing anything on a big scale to get restaurateurs or designers to listen and start accommodating people of size,” said Peggy Howell, the public relations director for the fat-acceptance organization, which has 11,000 members.

Howell, who weighs about 300 pounds, said when she and friends find a restaurant they like, they sometimes bring their own comfortable folding chairs.

Danny Meyer, whose restaurants include the Shake Shack chain and high-end destinations like Union Square Cafe, said customers’ size is a new consideration. “I don’t believe we have ever designed a restaurant saying, ‘Let’s make sure there are two tables that can accommodate someone who is larger,’” he said.

Still, Meyer expects hosts to respond quickly when a plus-size diner walks through the door. “There are always tables in a restaurant that are more commodious for large people,” he said. “So within three seconds you calculate in your mind, ‘Of the four tables we have left, which one would they be more comfortable?’”

Ample, a review app launched last year, at first focused on medical offices, but restaurant reviews quickly became popular, said Alissa Sobo, a founder.

Sobo advises restaurant owners to encourage the staff to gently suggest a more comfortable table or offer to find an armless chair for bigger customers. “Everyone I know would find that a kindness, not an insult.”