Eli Lilly vs Novo Nordisk: Which Company Will Dominate the Weight Loss Drug Market in 2026?

Eli Lilly (NYSE: LLY) and Novo Nordisk (NYSE: NVO) have seen revenue climb in recent years thanks to their expertise in one particular area: weight loss drugs. The companies are leaders in this market that analysts expect to reach nearly $100 billion by 2030. Today, they each sell injectable drugs, though Novo recently scored the first-ever approval for an oral drug of this particular class. And Lilly's oral candidate, under regulatory review right now, may be next.

The companies make GLP-1 drugs, products that interact with hormonal pathways involved in the digestion process -- and these types of drugs have proven their popularity worldwide, with demand even surpassing supply at certain points.

So now, with the era of weight loss pills about to start, it's a great time to take a closer look at each of these pharma giants. Which company will dominate the weight loss drug market in 2026? Let's find out.

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The case for Novo Nordisk

Novo has benefited from the first-to-market advantage with both the injectable weight loss drugs and now with the oral format. The company won approval for Ozempic, a GLP-1 drug for type 2 diabetes, in late 2017 and launched the drug in early 2018. Doctors also have prescribed the product off-label for patients aiming to shed pounds, and that greatly expanded the revenue opportunity.

The company followed up with the same peptide -- semaglutide -- commercialized specifically for weight loss as Wegovy in 2021. And just recently, regulators approved Wegovy in pill format.

This portfolio continues to drive growth at Novo, with obesity care generating revenue growth of 37% to 59.9 billion Danish kroner (about $9 billion) in the first nine months of 2025.

The case for Eli Lilly

Eli Lilly won approval for its tirzepatide under the names Mounjaro for type 2 diabetes and Zepbound for weight loss -- in 2022 and 2023, respectively. Like Novo, it saw sales soar as doctors initially prescribed its diabetes drug off-label for weight loss too.

Lilly's drugs are dual GLP-1/GIP receptor agonists, meaning they act on two hormonal pathways instead of just one -- so they're slightly different from Novo's product.

Lilly, too, has seen growth explode higher, and Mounjaro and Zepbound are driving revenue gains at the pharma company. In the recent quarter, for example, the two drugs together brought in about $10 billion in revenue -- and overall sales surged 54% due to volume growth in these drugs.

Lilly recently submitted orforglipron, its oral candidate, for regulatory review, so if all goes smoothly, it may soon join rival Novo in this new market.

Which company will dominate in 2026?

Novo Nordisk and Lilly both have proven the strength of their products, and demand has been high for them in recent years. But in my view, Lilly has the upper hand even though Novo has beaten the company to market on each occasion.

Here's why. First, Lilly has been gaining market share more quickly as it invested heavily in manufacturing to address product shortage issues -- about a year ago, Lilly pledged to double its U.S. manufacturing investment since 2020 to more than $50 billion.

Lilly also has benefited as studies supported the stronger efficacy of its product. In a head-to-head trial, Zepbound offered a 47% greater relative weight loss versus Wegovy after 72 weeks of treatment. The Lilly drug resulted in weight loss of about 20% compared to just under 14% for the Novo product.

Meanwhile, Lilly's orforglipron, though it hasn't yet been approved, offers a clear advantage over oral Wegovy. When patients take Wegovy in pill form, they must take it on an empty stomach with a sip of water, then wait a half-hour before eating, drinking, or taking other medications. Orforglipron doesn't involve such restrictions since it's more easily absorbed by the body. People seeking a weight-loss pill generally are looking for convenience, and Lilly offers this.

Of course, Novo still should continue to see growth as demand for weight loss drugs marches on, but considering the points I just mentioned, Lilly may dominate the market in 2026 and potentially down the road, too.

Adria Cimino has no position in any of the stocks mentioned. The Motley Fool recommends Novo Nordisk. The Motley Fool has a disclosure policy.