GLP-1 Boom Accelerates Nationwide Shift in Size Curves, Putting $5 Billion in U.S. Apparel Retail Inventory at Risk, According to New Impact Analytics Study

Analysis Underscores the Financial Strain of Misaligned Size Demand and Inventory Planning, Reveals a Visible Rise in Returns

NEW YORK, Sept. 29, 2025 (GLOBE NEWSWIRE) -- Rising use of GLP-1 medications including Ozempic, Mounjaro, and Wegovy comes as U.S. apparel retailers experience a material shift in size demand and increasing returns. This trend is creating the potential for up to $5 billion in margin risk, according to a new analysis from Impact Analytics, a leading provider of AI-native planning, pricing, and forecasting software.

The report, Retail’s $5B Blind Spot: How GLP-1s Are Breaking Size Curves, analyzed national sales and returns data from leading apparel retailers between 2022-2024. Impact Analytics finds that demand for larger sizes (L, XL, XXL) has fallen while sales of smaller sizes are rising—which could leave 400 million apparel units misaligned with customer demand by 2027 if the trend accelerates.

“GLP-1 drugs are upending America’s size curve in real time—and traditional retail industry planning processes are not ready,” said Prashant Agrawal, Founder and CEO of Impact Analytics. “The rise of GLP-1s is collapsing traditional demand patterns at a speed retailers have never experienced before. Our data shows billions of dollars in retail margins for inventory are at risk unless brands start planning for the shopper of 2027, instead of the shopper of 2022. Retailers must act now to recalibrate size curves or be stuck discounting unsold stock while missing the opportunity to serve tomorrow’s consumer with full margin integrity.”

Impact Analytics first spotted the warning signs in 2024, when New York City—the nation’s largest market for non-diabetic GLP-1 prescriptions—saw traditional apparel size curves begin to collapse. One year later, the same trend is emerging nationwide. Today, more than 12% of U.S. adults have tried GLP-1 medications and 6% are actively using them. As a result, demand for larger apparel sizes (L, XL, XXL) is falling, while sales of smaller sizes are steadily rising. With GLP-1 use projected to reach 8% of adults by 2027, the shift in shopping patterns is expected to accelerate. Returns are up across the board as shoppers navigate changing shapes and sizes.

Key findings:

• Size curve collapse (2022-2024): Notable gains in smaller sizes across multiple categories—women’s bottoms and tops, men’s M/L ranges — alongside declines in larger sizes. Between 2022–2024, demand increased for small sizes and decreased for large sizes:
  • Sales of women’s bottoms size 26 and smaller, including jeans, pants, and skirts, increased by 3 percentage points, while sizes 27-30 declined by 2.6 percentage points.
  • Women’s tops, including blouses, shirts, and T-shirts, saw XS-S sizes increase by 2 percentage points while L and XL declined by the same amount.
  • Women’s shapewear, such as bodysuits and leggings, saw S/M demand grow by 1.7 percentage points with XL and higher falling by nearly the same margin.
  • Men’s bottoms in sizes 30-35 increased by 1.7 percentage points, while sizes 36 and higher declined by the same margin.
  • Men’s tops in M/L sizes increased by 2.7 percentage points, while XL and XXL fell by 3.5 percentage points.
• Returns are rising: Returns climbed materially, with women’s bottoms up +2.9 percentage points and men’s tops up +1.3 points, signaling widening size mismatches.
• Scale of impact: Modeling suggests as many as 400 million apparel units could be misallocated by 2027 if current trends continue, representing roughly $5 billion in margin risk.
• Acceleration expected: With expanded FDA approvals and insurance coverage, GLP-1 adoption is projected to rise further, potentially increasing pressure on size demand curves and traditional planning models.
  

Methodology
The analysis combines aggregated point-of-sale and returns data from major U.S. brick-and-mortar and online apparel retailers, using machine-learning models to map changes in size demand and simulate inventory exposure through 2027.

Download the full report, Retail’s $5B Blind Spot: How GLP-1s Are Breaking Size Curves, here.

About Impact Analytics
Impact Analytics delivers AI-native SaaS solutions and consulting services that help companies maximize profitability and customer satisfaction through deeper data insights and predictive analytics that leverage Agentic AI. With a fully integrated end-to-end platform for planning, forecasting, merchandising, pricing, and promotions, Impact Analytics empowers companies to make smarter decisions based on real-time insights, rather than relying on last year’s inputs to forecast and plan this year’s business. Powered by over one million machine learning models, Impact Analytics has been at the forefront of AI innovation for a decade, setting new benchmarks in forecasting, planning, and operational excellence across the retail, grocery, manufacturing, and CPG sectors. Recognized for innovation and growth by Fortune, Financial Times, Inc. 5000, and the RIS Leaderboard, Impact Analytics continues to lead the way in shaping the future of business intelligence. Think differently about AI and learn more at www.impactanalytics.co.

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