Weight-loss treatments are a huge business, and business is booming. More than 750 million people worldwide are obese. According to Morgan Stanley research, the market for such medicines will grow to reach $77 billion by 2030, up from a tiny fraction of that before 2020.

Eli Lilly (LLY 1.19%) is working to capture as much of that market as it can, and it's probably going to succeed. Here's why.

The juggernaut is picking up speed

Regulators at the Food and Drug Administration (FDA) just approved expanding the indications for tirzepatide, Eli Lilly's type 2 diabetes drug, to include treating obesity. With that, the drugmaker is now entering what may prove to be one of the most intense periods of its history. Tirzepatide, which is currently approved for sale under the trade name Mounjaro, will be sold to treat obesity under the name Zepbound. It certainly won't be the last weight-loss drug the business brings to the market.

In fact, Eli Lilly's plan through the end of the decade is to use any means available to commercialize additional entrants. In the words of its chief scientific officer, Dan Skovronsky, "our goal is to exploit every single idea [in the obesity therapies segment] until we get data that says we shouldn't."

In practice, the business is running clinical trials to test higher dosages of its marketed candidates, while also advancing fresh ones and testing different combinations of its proven assets. Research and development (R&D) expenditures are a principal part of its capital allocation strategy. Furthermore, it's vigorously making acquisitions of promising biotechs.

Earlier this year it paid about $1.9 billion in cash for Versanis Bio, a biotech pursuing cardiometabolic treatments that are currently in mid-stage clinical trials, including for obesity. As Versanis' candidate uses a different mechanism of action than Zepbound, management has high hopes that it could be combined with Zepbound or other portfolio assets to perform even better. As you'll see, that hope is a key theme in Eli Lilly's strategy for the obesity market.

Via its venture capital operation, the drugmaker joined several other groups in early November to make an investment in OrsoBio, a biotech pursuing four investigational therapies for obesity, diabetes, and other metabolic disorders. One of those programs is in phase 2 clinical trials, another is in phase 1, and the other two are still in preclinical testing.

Critically, all of OrsoBio's programs use distinct mechanisms of action that are not shared with each other, or with anything in Eli Lilly's pipeline or its portfolio of commercialized medicines. The biotech's management thinks that its candidates could thus potentially be co-administered with medicines like Zepbound, delivering superior effects, and its new owner almost certainly agrees.

The brutal math of the drug development process means that there's a solid chance none of OrsoBio's attempts will succeed in commercializing a new medicine. But that's why Lilly's leaders are setting up an abundance of opportunities to take a shot at the goal.

Eli Lilly echos the hopes of OrsoBio that bundling multiple candidates will create a more effective treatment than one medicine could accomplish alone. Its collection of obesity treatments in clinical trials features programs with overlapping physiological targets and very similar or identical mechanisms of action -- a move that would usually be considered suspect according to the standard biopharma pipeline strategy playbook.

For Eli Lilly, the risk of a pipeline wipeout from very similar candidates failing their clinical trials as a group due to a shared flaw is much lower than normal. After all, it just succeeded in expanding tirzepatide's indications to include obesity, which means that regulators are (at least for now) sufficiently convinced that the drug's two mechanisms of action are safe and effective.

Therefore, follow-on candidates with the same mechanisms of action are unlikely to face an exceptional degree of scrutiny, and the associated clinical trials are much more likely to report favorable results than wholly unproven approaches. The bigger risk is that eventually the company's products might cannibalize each other's market share.

The groundwork for a profitable future is already in place

Still, the benefits of the company's strategy could be immense. Given how large the market for obesity therapies is, selling a collection of different options for treatment means being able to capture niches that would otherwise be difficult to reach. Obesity carries a huge number of diverse comorbidities ranging from hypertension to arthritis to depression, each of which could imply a different ideal treatment. Eli Lilly's clear ambition is to sell a specialized medicine as the ideal treatment for practically any combination of obesity-related conditions.

At the moment, its ambition is clearly more expansive than is true of its biggest competitor in the market, Novo Nordisk, which isn't currently as aggressive in developing its drug portfolio. In the long term, investors should anticipate Eli Lilly's control over the market to yield many billions of dollars of revenue, even if Novo Nordisk continues to challenge it. And that's a big reason to consider buying the stock.