Here's Why I Think Every Investor Needs to Invest in These "Miracle" Drugs

Sales and profits from GLP-1 weight-loss and diabetes drugs like Ozempic and Wegovy are already huge. They're only going to get bigger.

Eli Lilly's (NYSE: LLY) GLP-1 drug tirzepatide, which is marketed as Mounjaro for type 2 diabetes and Zepbound for obesity, dethroned Merck's (NYSE: MRK) cancer drug Keytruda last year to become the world's best-selling drug.

Novo Nordisk's (NYSE: NVO) sales of the GLP-1 drugs Wegovy and Ozempic pushed the drug manufacturer's market cap above the GDP of its home country, Denmark.

So, did investors who didn't buy these stocks years ago miss the boat?

Hardly. The numbers mentioned above are just the beginning. Morgan Stanley forecasts that the market for obesity miracle drugs will reach $190 billion by 2035, more than double its 2025 level. Right now, that growth is being driven by new oral treatments, expected to be adopted by consumers at a faster pace than injection-based delivery systems, and by expanded coverage from Medicare, the largest payer for healthcare services in the U.S.

But I think those predictions are far too small. Because medical researchers continue to find new and novel uses for the drugs, apart from obesity and weight loss. I believe these are truly miracle drugs that will cause a tectonic shift in the healthcare industry. It's definitely not too late to invest, as most of the growth in these drugs lies ahead, not in the past.

New markets and new use cases for GLP-1 drugs

First, there are international markets, largely untapped so far (outside of Europe). Morgan Stanley estimates there are more than 1 billion people with obesity living outside the U.S. To date, adoption in foreign markets has been constrained by several factors, including affordability, needle aversion, and safety concerns -- all of which can be overcome. The investment bank's research mentions Brazil and China, in particular.

And then there are new use cases for GLP-1 drugs. The National Institutes of Health (NIH) says that the medicines also improve outcomes in people with cardiovascular, kidney, liver, arthritis, and sleep apnea disorders. Those improvements are mediated in part through anti-inflammatory and metabolic pathways.

Image source: Getty Images.

And there will be more uses in the future, I predict, some of them astounding. For example, a recent study conducted on mice and funded by the National Institutes of Health (NIH) has shown that the GLP-1 drug semaglutide (made by Novo Nordisk) extended lifespan in older, healthy mice by tempering the detrimental effects of aging.

Of course, researchers have long known that calorie restriction can have anti-aging benefits. And GLP-1 drugs are designed to suppress appetite, thereby reducing calorie intake. But the new study, conducted at the University of California, found that the drugs' effects on mice could be more than just a consequence of lower-calorie diets.

In fact, the new study in healthy older mice offers evidence that these drugs may slow physiological aging itself. According to the NIH press release: "Compared with a control group, mice treated with the drug showed improved muscle and cognitive function. Gene expression analysis showed that several hallmarks of natural aging, such as increased inflammation and reduced regenerative capacity, were reduced in treated animals."

More research is needed, but the future looks bright

I assume that semaglutide's anti-aging effects in the study could be replicated with tirzepatide. And that should be fantastic news for both Novo Nordisk and Eli Lilly. Of course, the research remains a long way from establishing the same anti-aging results in humans. But if people believe it might, that will only encourage the adoption of the drugs.

Expanded use of GLP-1 drugs domestically and internationally for weight loss, expanded use cases for the drugs, and potentially more to come; there are many reasons to think GLP-1 drugs can revolutionize healthcare.

That's why I firmly believe that every investor should have some portion of their portfolio in this rapidly expanding market. It's worth looking at Novo Nordisk, Eli Lilly, and even Pfizer and Merck, which don't yet have a GLP-1 drug on the market but have several in development. That's where to start.

Matthew Benjamin has positions in Novo Nordisk. The Motley Fool has positions in and recommends Eli Lilly, Merck, Novo Nordisk, and Pfizer. The Motley Fool has a disclosure policy.