NEW YORK, Aug 13 (Reuters) - Novo Nordisk CEO Mike Doustdar said investors are underestimating the demand for differentiation among obesity drugs, and that new treatment options like pills will keep it from becoming a winner-take-all battle with rival Eli Lilly.

Novo was first to bring a highly effective GLP-1 weight-loss injection, Wegovy, to the U.S. market, but is under pressure to regain ground lost to Lilly's Zepbound in a business that analysts expect will be worth more than $100 billion a year by 2030.

Doustdar, who took the helm at the Danish drugmaker a year ago, said that patients are just beginning to understand which GLP-1 drug is best suited to them, and he expects more segmentation as new medicines are approved. More than 100 million U.S. adults are classified as obese. 

"Right now the investor community has thought this is supposed to be a zero-sum game between two players - there's a loser and a winner," Doustdar said in an interview with Reuters on Wednesday.

"As you foresee the future of GLP-1s and obesity and weight-loss drugs, it will not be Coke versus Pepsi. It will be Coke and Pepsi and Fanta and Dr Pepper and Red Bull. People are thirsty, and they can make their choices," he said.

Novo shares have fallen sharply since hitting a peak in 2024, while Lilly shares have continued to rise, pushing the company's market capitalization above $1 trillion.

Doustdar compared his vision for Novo's obesity portfolio to its insulin business for diabetes, where the company sells 50% of the world's insulins across 12 different brands, rather than dominating with one specific treatment.

"They all reduce sugar, but they do also different things. GLP-1s all reduce weight, but they all do different things," he said.

Novo's new pill version of Wegovy and a pipeline of experimental drugs are a key focus for investors.

Doustdar said the Wegovy pill currently has 90% market share in the oral GLP-1 market, in part because it has data showing better weight loss than Lilly's Foundayo pill.

He said it was difficult to project what percentage of patients would end up using pills, but said "we're in a very good place if it becomes a 50-50 market" between oral medications and injections.

Novo said in January that pills could comprise more than a third of GLP-1 use by 2030.

Novo's experimental next-generation obesity drug CagriSema has disappointed investors in clinical trials, helping patients lose an average of 23% of their body weight compared to more than 25% for Zepbound.

Doustdar said CagriSema would still offer a powerful addition to existing treatments. The company aims to launch it next year.

CagriSema "has been written off pretty much by all investors," he said. "And I say to people, when is the last time a doctor had a single medicine in their toolbox to treat millions?"