Tim Gunn is a design educator, author and Emmy-winning co-host of “Project Runway.”

Barbie dolls clothes are displayed during the exhibition “Barbie, life of an icon” at the Museum of Decorative Arts. (Photo by Thierry Chesnot/Getty Images)

When I was chief creative officer for Liz Claiborne Inc., I spent a good amount of time on the road hosting fashion shows to highlight our brands. Our team made a point of retaining models of various sizes, shapes and ages, because one of the missions of the shows was to educate audiences about how they could look their best. At a Q&A after one event in Nashville in 2010, a woman stood up, took off her jacket and said, with touching candor: “Tim, look at me. I’m a box on top, a big, square box. How can I dress this shape and not look like a fullback?” It was a question I’d heard over and over during the tour: Women who were larger than a size 12 always wanted to know, How can I look good, and why do designers ignore me?

At New York Fashion Week, which began Thursday, the majority of American women are unlikely to receive much attention, either. Designers keep their collections tightly under wraps before sending them down the runway, but if past years are any indication of what’s to come, plus-size looks will be in short supply. Sure, at New York Fashion Week in 2015, Marc Jacobs and Sophie Theallet each featured a plus-size model, and Ashley Graham debuted her plus-size lingerie line. But these moves were very much the exception, not the rule.

Designers prepare to show their spring/summer 2017 collections to fashion insiders and fans. (Reuters)

I love the American fashion industry, but it has a lot of problems, and one of them is the baffling way it has turned its back on plus-size women. It’s a puzzling conundrum. The average American woman now wears between a size 16 and a size 18, according to new research from Washington State University. There are 100 million plus-size women in America, and, for the past three years, they have increased their spending on clothes faster than their straight-size counterparts. There is money to be made here ($20.4 billion, up 17 percent from 2013). But many designers — dripping with disdain, lacking imagination or simply too cowardly to take a risk — still refuse to make clothes for them.

In addition to the fact that most designers max out at size 12, the selection of plus-size items on offer at many retailers is paltry compared with what’s available for a size 2 woman. According to a Bloomberg analysis, only 8.5 percent of dresses on Nordstrom.com in May were plus-size. At J.C. Penney’s website, it was 16 percent; Nike.com had a mere five items — total.

I’ve spoken to many designers and merchandisers about this. The overwhelming response is, “I’m not interested in her.” Why? “I don’t want her wearing my clothes.” Why? “She won’t look the way that I want her to look.” They say the plus-size woman is complicated, different and difficult, that no two size 16s are alike. Some haven’t bothered to hide their contempt. “No one wants to see curvy women” on the runway, Karl Lagerfeld, head designer of Chanel, said in 2009. Plenty of mass retailers are no more enlightened: Under the tenure of chief executive Mike Jeffries, Abercrombie & Fitch sold nothing larger than a size 10, with Jeffries explaining that “we go after the attractive, all-American kid.”

This is a design failure and not a customer issue. There is no reason larger women can’t look just as fabulous as all other women. The key is the harmonious balance of silhouette, proportion and fit, regardless of size or shape. Designs need to be reconceived, not just sized up; it’s a matter of adjusting proportions. The textile changes, every seam changes. Done right, our clothing can create an optical illusion that helps us look taller and slimmer. Done wrong, and we look worse than if we were naked.

Acid attack survivor Reshma Quereshi takes on the catwalk of FTL Moda during New York Fashion Week hoping to inspire other survivors. (Reuters)

Have you shopped retail for size 14-plus clothing? Based on my experience shopping with plus-size women, it’s a horribly insulting and demoralizing experience. Half the items make the body look larger, with features like ruching, box pleats and shoulder pads. Pastels and large-scale prints and crazy pattern-mixing abound, all guaranteed to make you look infantile or like a float in a parade. Adding to this travesty is a major department-store chain that makes you walk under a marquee that reads “WOMAN.” What does that even imply? That a “woman” is anyone larger than a 12, and everyone else is a girl? It’s mind-boggling.

Project Runway,” the design competition show on which I’m a mentor, has not been a leader on this issue. Every season we have the “real women” challenge (a title I hate), in which the designers create looks for non-models. The designers audibly groan, though I’m not sure why; in the real world, they won’t be dressing a seven-foot-tall glamazon.

This season, something different happened: Ashley Nell Tipton won the contest with the show’s first plus-size collection. But even this achievement managed to come off as condescending. I’ve never seen such hideous clothes in my life: bare midriffs; skirts over crinoline, which give the clothes, and the wearer, more volume; see-through skirts that reveal panties; pastels, which tend to make the wearer look juvenile; and large-scale floral embellishments that shout “prom.” Her victory reeked of tokenism. One judge told me that she was “voting for the symbol” and that these were clothes for a “certain population.” I said they should be clothes all women want to wear. I wouldn’t dream of letting any woman, whether she’s a size 6 or a 16, wear them. A nod toward inclusiveness is not enough.

This problem is difficult to change. The industry, from the runway to magazines to advertising, likes subscribing to the mythology it has created of glamour and thinness. Look at Vogue’s “shape issue,” which is ostensibly a celebration of different body types but does no more than nod to anyone above a size 12. For decades, designers have trotted models with bodies completely unattainable for most women down the runway. First it was women so thin that they surely had eating disorders. After an outcry, the industry responded by putting young teens on the runway, girls who had yet to exit puberty. More outrage.

But change is not impossible. There are aesthetically worthy retail successes in this market. When helping women who are size 14 and up, my go-to retailer is Lane Bryant. While the items aren’t fashion with a capital F, they are stylish (but please avoid the cropped pants — always a no-no for any woman). And designer Christian Siriano scored a design and public relations victory after producing a look for Leslie Jones to wear to the “Ghostbusters” red-carpet premiere. Jones, who is not a diminutive woman, had tweeted in despair that she couldn’t find anyone to dress her; Siriano stepped in with a lovely full-length red gown.

Several retailers that have improved their plus-size offerings have been rewarded. In one year, ModCloth doubled its plus-size lineup. To mark the anniversary, the company paid for a survey of 1,500 American women ages 18 to 44 and released its findings: Seventy-four percent of plus-size women described shopping in stores as “frustrating”; 65 percent said they were “excluded.” (Interestingly, 65 percent of women of all sizes agreed that plus-size women were ignored by the fashion industry.) But the plus-size women surveyed also indicated that they wanted to shop more. More than 80 percent said they’d spend more on clothing if they had more choices in their size, and nearly 90 percent said they would buy more if they had trendier options. According to the company, its plus-size shoppers place 20 percent more orders than its straight-size customers.

Online start-up Eloquii, initially conceived and then killed by the Limited, was reborn in 2014. The trendy plus-size retailer, whose top seller is an over-the-knee boot with four-inch heels and extended calf sizes, grew its sales volume by more than 165 percent in 2015.

Despite the huge financial potential of this market, many designers don’t want to address it. It’s not in their vocabulary. Today’s designers operate within paradigms that were established decades ago, including anachronistic sizing. (Consider the fashion show: It hasn’t changed in more than a century.) But this is now the shape of women in this nation, and designers need to wrap their minds around it. I profoundly believe that women of every size can look good. But they must be given choices. Separates — tops, bottoms — rather than single items like dresses or jumpsuits always work best for the purpose of fit. Larger women look great in clothes skimming the body, rather than hugging or cascading. There’s an art to doing this. Designers, make it work.