Econ expert weighs in: Will slimming down with GLP-1s widen health disparities?

Johns Hopkins Carey Business School Professor of Economics Mario Macis explores the value, costs, and unknowns associated with the boom in weight-loss drugs. Macis is an applied economist with a broad range of interests at the intersection of markets, policy, and society, with a special emphasis on health-related issues.

Last month Pfizer announced it will acquire obesity-drug developer Metsera for about $4.9 billion upfront, and up to $7.3 billion with milestones. The move marks Pfizer’s return to the GLP-1 field after discontinuing its own oral candidate, Danuglipron, earlier in 2025, upon evidence of gastrointestinal side effects and potential liver injury.

Metsera’s appeal lies in its next-generation weight-management pipeline: a promising once-monthly injectable, longer-acting combinations, and oral approaches aimed at making treatment easier to take and sustain. If these formats deliver comparable results with fewer side effects and less frequent dosing, they could broaden effective demand by improving convenience and adherence—and by lowering the real cost of care over time.

GLP-1–based therapies began in diabetes and then proved effective for chronic weight management. As endocrinologist and former dean of medicine at Harvard University Jeffrey Flier has recounted, Pfizer helped launch the earliest GLP-1 program in the late 1980s but walked away—misreading the market for injectables—ceding a future blockbuster class to competitors. Today’s Metsera deal is a costly “full circle.”

Roughly 40% of U.S. adults live with obesity; globally, about one in eight people. The medical, economic, and social burdens total hundreds of billions annually. Individual willingness-to-pay reflects private benefits like health, appearance, and energy. Payers’ willingness depends on credible evidence that these drugs offset downstream costs. Given the prevalence and demand, many analysts now project that GLP-1-based weight-loss medicines could become the best-selling drugs of all time.

U.S. prices are high (often $1,000–$1,600/month), though many self-pay discount programs now advertise about $499/month at participating pharmacies. Medicare still excludes anti-obesity drugs for weight loss but now allows Wegovy for cardiovascular indications; Medicaid coverage remains patchy and shifting; and roughly 35–45% of large-employer plans cover GLP-1s for weight loss (higher among the very largest employers). The CBO estimates that broad Medicare coverage could cost $35B over nine years, keeping public payers cautious.

Single-payer systems (e.g., the U.K.’s NHS) can set uniform prices and coverage after centralized review (such as NICE’s approval of Wegovy). In the fragmented U.S. system, payer churn weakens incentives. If a private insurer funds GLP-1s today, the future savings from fewer complications may accrue to Medicare later. That mismatch encourages strict prior authorization and uneven access despite strong demand.

GLP-1 use is already nudging consumer behavior. U.S. households with a GLP-1 user spend about 5–6% less on groceries in the first six months—primarily fewer calorie-dense processed foods—though the persistence of these effects remains to be seen.

Long-term safety, durability of weight loss, optimal treatment duration, and adherence remain uncertain. If prices stay high and coverage limited, uptake may skew toward higher-income patients, widening health disparities.

Pfizer’s Metsera acquisition underscores how the economics of innovation hinge on timing and risk perception. 35 years after exiting early GLP-1 work, Pfizer is paying billions to re-enter a market defined by vast willingness-to-pay, high expected benefits, and still-unresolved risks—an object lesson in how uncertainty shapes both science and markets.

The past few years have brought spectacular advances in medicine—from the new generation of weight-loss and metabolic drugs, to mRNA vaccines against COVID-19, to promising gene and cell therapies that might soon treat once-incurable diseases, and the first CRISPR-based treatments now reaching patients. These and other breakthroughs highlight the power of scientific progress and might, perhaps, help to slow or even reverse the growing skepticism toward science and medicine.