The denim market is feeling the impact of GLP-1 medication.

A new consumer survey by Trimi Health, an online telehealth platform that provides access to GLP-1 medications for weight management, found that “jeans are the first casualty of weight loss,” with 90 percent of respondents calling the denim category “disrupted” and 42 percent saying their jeans are now completely unwearable—the most of any clothing category.

Trimi surveyed 737 U.S. adults who currently use, previously used, or are on a maintenance dose of a GLP-1 medication. Of the respondents, 46 percent were millennials, 30 percent Gen X, 15 percent Gen Z, and 8 percent Baby Boomers.

A closet of ill-fitting clothes is proving to be one of the most expensive side effects of the drugs. The average cost of rebuilding a wardrobe with clothes that fit is $328, and more than half are turning to retailers they never shopped before treatment.

Sixty-two percent of GLP-1 users said they can now fit into brands or stores they once avoided, and 55 percent have started buying from brands they never shopped before treatment.

GLP-1 users named Old Navy, American Eagle and Amazon as their top new brands since starting treatment. Free People is the biggest gainer among the brands measured, doubling from 5 percent to 10 percent of shoppers, as 27 percent “trade up to a contemporary, premium, or athleisure brand they never shopped before,” Trimi reported.

Anthropologie, Lululemon and Nordstrom Rack are also seeing gains.

By comparison, the brands and retailers respondents bought from before treatment are counting major losses. Seventy percent of GLP-1 users said they have left the plus-size stores they shopped at before.

Plus-size retailers Lane Bryant and Torrid are experiencing the largest share loss, down 72 percent and 65 percent, respectively, followed by JCPenney, Walmart and Target.

Rebuilding process

The survey revealed mixed feelings about how consumers are rebuilding their wardrobes. While 67 percent have “stopped buying the clothes they used to hide behind,” four in five GLP-1 users said they have delayed purchasing new clothes until their size stabilizes.

For 41 percent of respondents, shopping secondhand is a solution while sizing down.

Meanwhile, ill-fitting clothes are ending up in thrift stores, storage units and landfill. The survey found that 68 percent of respondents donate their unwanted clothing, while 54 percent store clothes “just in case” and 28 percent offload apparel on resale platforms. Nearly half—46 percent—said they “threw away” clothes that no longer fit.