The gold rush for anti-obesity medicines is here, and the stakes are high. Per a report by Morgan Stanley Research, the market for weight loss drugs will be worth around $77 billion by 2030, despite being worth only $2.4 billion in 2022.

Where should investors place their bets to gain some exposure to this hotter-than-hot trend? An investment in one of the established market leaders, like Eli Lilly (LLY 1.19%), could be sufficient -- but buying shares of an up-and-coming biotech like Viking Therapeutics (VKTX 7.92%) could pay off. It's time to evaluate these two alternatives.

This biotech is planning to take a bite out of the obesity drugs market

Viking Therapeutics isn't yet competing directly in the market for weight loss therapies, as it's a young biotech that hasn't gotten its first medicine approved. Nonetheless, per some phase 2 clinical trial data it published on Feb. 27, there is a good chance that will change soon enough.

In the trial, patients treated with the company's anti-obesity candidate VK2735 for 13 weeks experienced a 14.7% decline in their body mass, whereas patients receiving a placebo saw their weight decline by only 1.7%. The side effect profile was on average as tolerable for the patients taking the placebo as it was for the ones being treated with the drug. It should not surprise anyone that the stock surged by 137% on the day the results were published.

VK2735 will need to repeat its strong performance in a phase 3 trial and please regulators at the Food and Drug Administration (FDA) before it can generate any revenue. But without any clinical red flags in hand with its candidate, there is at present no reason to suspect that the next trial will go poorly or that the FDA will snub its request for approval afterward.

In 2023, its research and development (R&D) expenses were $64 million. And when considering that the business had more than $362 million in cash, equivalents, and investments as of its Q4 earnings report, Viking has more than enough money available to fund further efforts to get its candidate finished. Management is also keen to advance a new offering of the company's shares, which could raise in the ballpark of an additional $350 million if it proceeds as proposed on Feb. 27.

So it is reasonable to expect that Viking will experience wild growth from sales of its first product for obesity within the next few years, and that means its stock will likely continue to go up.

The pharma juggernaut isn't about to decelerate

Eli Lilly makes Zepbound, the medicine that's currently going head-to-head with Novo Nordisk's drug Wegovy for control of the weight loss therapies market. The fact that it's already making money indicates that it has a serious edge over Viking Therapeutics in terms of how investible the stock is.

In 2023, Zepbound brought in $176 million in sales between its approval in November and the end of the year. Since then, the company has struggled to manufacture enough of the drug to meet demand, even as it continues to scale up its manufacturing capacity. The product's first full year on the market will probably see sales on the order of billions, easily becoming a blockbuster drug, and it could even become one of the best-selling drugs of all time.

Aside from the coming windfall from Zepbound, the longer-term reason that Eli Lilly is probably the better weight loss drug stock is that its development pipeline of weight loss medicines is world class. It has two completely different programs in phase 3 clinical trials, with numerous additional efforts underway to expand the approved indications that Zepbound can be marketed for. And that's just with its internal R&D right now.

More than half of the new therapies in its pipeline are derived from business development deals in the form of acquisitions, licensing, or partnerships with other businesses, and management has stated that it's taking a similar approach to its medicines for metabolic diseases. In July 2023, it shelled out $1.9 billion to acquire Versanis, a biotech that was developing an antibody therapy for obesity, and other such deals may yet be in the wings.

With so much revenue today and so many additional opportunities to generate even more, Eli Lilly is practically guaranteed to have a large market share in obesity drugs for a very long time.

This choice comes down to preferences and perspectives

Today, Eli Lilly is the much better weight loss stock by virtue of the fact that it's already making billions in the market. Furthermore, its pipeline and aggressive business development stance regarding buying promising weight loss assets means that its dominance will probably continue for years to come, even if an upstart like Viking Therapeutics can find a sliver of the market to call its own.

Still, in terms of the anticipated pace of its top-line growth over the next five years, there is a very good chance that Viking will have it beat, assuming it can commercialize VK2735. Of course, Viking is by far the riskier choice, so it might not be the right option for everyone.

If you're on the fence, remember that the market for obesity therapies is so large that it could be worth considering a purchase of both stocks.