Why exactly does Old Navy charge plus-sized clothes for women more than plus-size clothes for men? On its website, the clothing company prices the women’s Rockstar Super Skinny Jeans as $27 for a regular size, and $40 for the plus-sized version. But the Men’s Slim-Fit Jeans remain $25 for all sizes.

It certainly sounds suspiciously discriminatory, and might even be interpreted as a form of body-shaming against women. That’s where Renee Posey, an Old Navy shopper turned activist, believes the company made a major faux-pas. “I noticed that they were charging $12-$15 more for plus-sized women’s jeans — but not up-charging jeans for ‘big’ men,” she wrote.

A “plus-sized” woman herself, Posey discovered the incongruence while shopping online. Outraged by the difference, she decided to start a petition on Change.org to demand Old Navy to adjust its pricing with a little more sensitivity to gender equality and body-shaming issues. “I was fine paying the extra money as a plus-sized woman, because, you know, more fabric equals higher cost of manufacture,” she writes on the petition. “However, selling jeans to larger-sized men at the same cost as they sell to smaller men not only negates the cost of manufacture argument, but indicates that Old Navy is participating in both sexism and sizeism, directed only at women.”

Another issue Posey points out is that the company separates the plus-sized clothing for women in its own section on the website, while all of the men’s sizes are placed together. “I don’t understand why myself and women like me are being singled out and forced to pay more by Old Navy, when our male counterparts are not,” she wrote. The petition has over 26,000 supporters, as of Wednesday.

But Gap Inc., which owns Old Navy and the Gap, claims that the pricing is higher for women’s plus-size items due to specialized designs and elements, such as waistbands, that aren’t used to make men’s large clothes. Gap, Inc. released a statement to several media outlets:

“Old Navy is proud to offer styles and apparel designed specifically for the plus size customer. For women, styles are not just larger sizes of other women’s items, they are created by a team of designers who are experts in creating the most flattering and on-trend plus styles, which includes curve-enhancing and curve-flattering elements such as four-way stretch materials and contoured waistbands, which most men’s garments do not include. This higher price point reflects the selection of unique fabrics and design elements.”

While it may be surprising to many, plus-sized clothing is becoming more and more common among Americans. Obesity affects every one in three Americans, according to the Centers for Disease Control and Prevention (CDC) — and 67 percent of the American population can be considered “plus-sized,” with the average woman being a size 14. As a result, more retail outlets must sell larger clothing sizes.

Whether or not Old Navy really requires more input to make women’s plus-sized items, it doesn’t appear there are any watchdogs or legal guidelines to keep an eye on such retail companies from taking advantage of the plus-size market. Perhaps Old Navy is cognizant of these issues, however, and it truly costs more to make more. But until then, it’s up to Posey and like-minded customers to bring the issue to light.