Real-World GLP-1 Prescriptions Quadruple Since 2021; Eli Lilly's Tirzepatide Overtakes Novo's Semaglutide in U.S. Market Share

A comprehensive real-world data tracking analysis published by Epic Research on May 22, 2026, reveals that population-level adoption of GLP-1 medications has experienced a massive, more than fourfold increase in the United States over the past five years. Crucially, the study provides the first concrete evidence that Eli Lilly’s tirzepatide (Mounjaro/Zepbound) has officially overtaken Novo Nordisk’s semaglutide (Ozempic/Wegovy) as the most frequently prescribed GLP-1 agent in the country.

Surging Prescriptions and Market Share Shifts

Using data from Cosmos—a massive dataset representing more than 304 million patient records across 2,000 hospitals and 47,000 clinics across all 50 U.S. states—Epic Research tracked quarterly prescription rates per 100,000 U.S. adults:

• The Quadruple Boom: GLP-1 prescription rates skyrocketed from 1,884 per 100,000 patients in the second quarter of 2021 to 8,819 per 100,000 patients in the first quarter of 2026.
• Tirzepatide Takes the Lead: In 2021, semaglutide dominated the landscape (roughly 680 prescriptions per 100,000) alongside older agents like dulaglutide. However, by Q1 2026, tirzepatide became the most prescribed agent at approximately 4,700 prescriptions per 100,000 patients, surpassing semaglutide, which stood at roughly 3,900 per 100,000 patients.
• Displacement of Older Agents: Older GLP-1 receptor agonists (such as dulaglutide and liraglutide) have seen a steady decline as patients and clinicians migrate to the superior efficacy of newer-generation dual-hormone therapies.

Population-Level Obesity Rates Show First Signs of Decline

For healthcare investors and public health officials, the most significant long-term finding of the Epic Research tracker is that the massive rise in GLP-1 adoption is finally translating into a measurable, population-level decline in obesity:

• The share of U.S. adults classified as obese stood at 42.3% in Q2 2021.
• After remaining relatively flat through 2022, the nationwide obesity rate began a steady decline, falling to 40.7% in the first quarter of 2026.
• Concurrently, the percentage of U.S. adults in the "healthy weight" category rose from 25.1% to 25.6%.

What This Means for Investors

1. Lilly’s Commercial Dominance: Despite Novo Nordisk's first-mover advantage with Wegovy's 2021 approval, Eli Lilly's Zepbound and Mounjaro have captured the leading share of U.S. prescriptions. This reflects the superior clinical weight loss profile of tirzepatide (up to 22.5% in SURMOUNT trials) and Lilly's aggressive supply-chain expansion.
2. Deflation of the Obesity Epidemic: This is the first empirical, multi-million-patient evidence that the obesity epidemic in the United States is starting to bend downward. A sustained decline in obesity is a secular headwind for companies focusing on chronic disease complications (e.g., cardiovascular disease, sleep apnea, type 2 diabetes medical devices) and a major tailwind for consumer discretionary sectors like apparel.