Stop and the Weight Comes Back: GLP-1, and the Real Constraint the Shortage Hid

Two years ago, Wegovy and Ozempic were drugs you couldn't fill at the pharmacy. The U.S. FDA placed some Wegovy doses on its shortage list in March 2022, and Ozempic in August 2022. That shortage is over. And where it lifted, a more important fact surfaced: stop the drug and the weight comes back. In the STEP 1 extension trial, participants who came off semaglutide regained about two-thirds of the weight they had lost within a year. The shortage had been hiding the real constraint. What was bound was not output—it was demand.

GLP-1 is an incretin hormone the gut releases when you eat. A GLP-1 receptor agonist mimics that signal—it raises the pancreas's insulin secretion and suppresses glucagon to lower blood sugar, and at the same time acts on the brain's satiety center and slows gastric emptying to cut appetite and weight. Semaglutide (Ozempic, Wegovy) acts on the single GLP-1 receptor; tirzepatide (Mounjaro, Zepbound) acts on two, GIP and GLP-1. The effect lasts only while the drug is taken. Stop the signal and the appetite returns.

The Shortage Demand Made—and What It Hid

The cause was simple. Demand outran capacity. After Wegovy was approved for weight management in June 2021, demand surged; Novo Nordisk said that as of May 2024 roughly 25,000 people a week were starting Wegovy in the United States—about five times the December 2023 figure.

The shortage lifted across 2024 and 2025. The FDA declared the tirzepatide injectable shortage resolved on 19 December 2024 and the semaglutide injectable shortage on 21 February 2025. Over the same span Novo invested heavily in capacity—$6.5 billion in the United States in 2025, and $16.5 billion to acquire Catalent, the fill-finish contractor.

Resolution did not end in a return to normal. During the shortage, pharmacy compounding—legally copying a drug in short supply—at one point supplied roughly 30% of U.S. GLP-1 volume. That copying stood on a single exception: "shortage." When the shortage lifted, the legal basis vanished, and the FDA imposed deadlines to stop compounding semaglutide (22 April 2025 for 503A pharmacies, 22 May for 503B facilities). In September 2025 it sent more than 55 warning letters to online sellers, and telehealth players like Hims and Ro exited the compounded-semaglutide business. Novo claimed that in its own testing the impurities in some compounded injectables ran as high as 86%. The 30% shadow market the shortage had legalized became illegal the moment the shortage ended.

The shortage lifted; the demand does not. Because once you stop the drug, the effect is gone.

Stop, and it comes back · STEP 1 extension trial: about two-thirds of lost weight regained within a year of stopping semaglutide · Cleveland Clinic real-world analysis (~8,000 patients): about 55% of obesity patients who stopped GLP-1 regained weight after a year; 45% maintained or lost more Sources: STEP 1 extension (Wilding 2022) · Cleveland Clinic (Diabetes Obes Metab, 2026-03) · limited to trial and real-world conditions

The drug manages a chronic condition—obesity. It does not cure it. A patient who starts once keeps getting the prescription, and demand does not come down even when manufacturing catches up. The shortage was a passing symptom of that demand.

The Competition Moves Off Efficacy

Once supply leveled out, the variables that distinguish the drugs multiplied. Efficacy became the price of entry. In SURMOUNT-5, the head-to-head trial, mean weight loss at 72 weeks on the maximum tolerated dose was −20.2% for tirzepatide and −13.7% for semaglutide. Revenue followed the same order: in 2025, Lilly's Mounjaro and Zepbound combined are estimated at roughly $36 billion, Novo's semaglutide franchise at roughly $33 billion.

The new differentiators sit outside efficacy. Price comes first. Semaglutide's compound patent expired in Canada on 4 January 2026—a G7 first—and in India, China, and Brazil in April 2026. In the United States, the United Kingdom, and much of Europe it stays protected through 2031. In India, where the patent has lapsed, more than 40 drugmakers are preparing copies, and the monthly price has fallen from 10,000–16,000 rupees for the brand to as little as about 1,290 rupees. A month of the same molecule splits nearly tenfold by region.

The route split, too. On 22 December 2025 the FDA approved oral semaglutide—a Wegovy pill, 25 mg once daily—for weight management. The first oral GLP-1 obesity drug, it showed mean weight loss of 16.6% under adherence in the OASIS 4 trial. On 1 April 2026, Lilly's orforglipron (Foundayo) was approved. A small-molecule oral rather than a peptide, it reached only about 11% mean loss at its top dose in trials—but it opened a path you swallow instead of inject.

The indications widened, too. In the SELECT trial (more than 17,600 participants), overweight and obese patients with prior cardiovascular disease and no diabetes who took semaglutide 2.4 mg cut their risk of major cardiovascular events by 20% (6.5% versus 8.0%). The FDA approved the indication. The pool of eligible patients widened beyond obesity and diabetes.

The Market Has Already Ruled

Whether the drug that leads on efficacy also takes the market is decided outside efficacy. The capital markets have already priced that split in.

Sources: SURMOUNT-5 (NEJM) · Lilly and Novo 2026 guidance · share and market cap per CNBC / securities analysis, as-of 2025 to 2026-02

This is the first mover's fall. Novo, once the most valuable company in Europe, has seen its market cap drop roughly 75% from its June 2024 peak to below about $160 billion by February 2026. While Lilly guides to roughly 25% growth in 2026, Novo has warned of the first revenue decline in its modern history. CagriSema, the next-generation obesity drug Novo brought as its counter, missed the primary endpoint in its head-to-head against Zepbound (REDEFINE 4), and the stock fell about 16% more right after the readout. The company that built first ceded share to the company that takes off more weight (Lilly about 60% to Novo about 40%).

A Drug That Outgrows Its Category

Demand you cannot quit pushes the obesity drug out past the pharmaceutical category. By Danske Bank's analysis, Novo alone accounted for about half of Denmark's GDP growth in 2024, and the company employed roughly 30,000 people. When the company wobbled, pharmaceuticals' contribution to Denmark's merchandise export growth sank from 8.1 percentage points in 2024 to 1.3 percentage points in 2025. One company's trial results move a nation's growth rate. (The same structure—one actor moving an entire system—shows up in the KOSPI, where half the index is two companies.)

Consumption moves, too. Households using GLP-1 cut grocery spending by an average of 5.3% within six months of starting, and by more than 8% among high-income households. About 23% of U.S. households have a user, and the industry estimates GLP-1 will account for about 35% of food-and-beverage sales by 2030.

It reaches the reader along two lines. On the paying side, U.S. Medicare will open a temporary "GLP-1 Bridge" from July 2026 through the end of 2027, supplying the drug to eligible beneficiaries at a $50 monthly copay. As of 2025, 49% of U.S. employer health plans at firms with 500 or more workers covered GLP-1 for weight loss, and at firms above 20,000 workers about two-thirds did. "Does my insurance cover it" has become a real variable. In Korea, Wegovy launched in October 2024 as a non-reimbursed drug (in the 500,000-won-a-month range) and Mounjaro in August 2025, and Novo cut its supply price by up to 40%. In December 2024 the Ministry of Health and Welfare banned remote prescribing and dispensing of obesity drugs.

What Ended and What Remains

The shortage is over. What ended was the shortage, not the demand. As long as the weight comes back when you stop, demand will not come down even when the plants catch up. On top of that, the field is rearranging—price (generics), route (oral), payment (insurance), capital (Novo, Lilly). In 2025, about 12% of U.S. adults had already used a GLP-1. The question the shortage was hiding is now clear: not who takes off more weight, but who can carry that un-quittable demand more cheaply, in a form easier to swallow, propped up by insurance.