Eli Lilly (LLY 1.07%) and Novo Nordisk (NVO -1.99%) are two of the most valuable healthcare stocks in the world, largely due to their successful diabetes and weight loss medications. They are also big players in the burgeoning GLP-1 weight loss market, and investors are paying large premiums for these stocks based on their potential.

But what's intriguing is that the potential may be even bigger than what analysts and investors are expecting. And that's because there may be even greater benefits associated with maintaining a healthier weight than the ones that are known today. One study suggests that it may even help reduce the risk of developing Alzheimer's.

Study shows that belly fat is linked to an increase risk of Alzheimer's

There are many illnesses and conditions which are associated with being obese, which is why it's paramount for many patients to maintain a healthy weight. But one particularly concerning illness which you may not have considered to be associated with weight gain is Alzheimer's. The disease robs people of their memories, and since it's a neurological issue, many people may not think that carrying a lot of weight could put them at risk for that disease, but a new study suggests that could indeed be the case.

According to a recent study in the U.S., visceral fat, or belly fat, could put a person at risk of developing Alzheimer's later on in life. Beta amyloids and tau proteins are signs of Alzheimer's disease, and they could be appearing decades before a person is diagnosed with the illness, as their visceral fat increases. As people gain weight, the area of the brain associated with memory also appears to shrink. As the process can take years, it heightens the need for people to maintain a healthy weight throughout their life.

Diet, exercise, and a GLP-1 drug?

The study didn't suggest taking GLP-1 drugs to help patients keep the weight off, but the conclusion was that reducing belly fat could be key in reducing the risk of Alzheimer's later on in life. Diet and exercise can be effective ways to maintain a healthy weight, but for people who struggle with that, taking a GLP-1 drug can be a key part of the long-term strategy as well.

Weight loss drugs such as Zepbound (Eli Lilly) and Wegovy (Novo Nordisk) could be crucial treatment options for patients looking to keep their weight down. In studies, they have helped people lose more than 15% of their body weight. And as there are more reasons to take these drugs beyond just weight loss, such as helping to prevent Alzheimer's, there may be an increase in healthcare coverage for these treatments, making them more widely accessible.

But it's important to note that while a study can be promising, it may not necessarily lead to a new indication for a drug, and it could take a while before regulators approve these treatments for other uses.

What does appear evident, however, is that there can be wide-ranging benefits to taking GLP-1 drugs beyond just losing weight. People can live healthier lives, and as health experts learn more about these drugs, they can become even more important to doctors and patients, leading to even more revenue growth for their respective businesses.

Should you hold a GLP-1 stock in your portfolio?

Zepbound and Wegovy have the potential to generate tens of billions in revenue for their respective companies. And as these businesses continue to invest into weight loss treatments and broaden their portfolios, they can be in prime positions to benefit from this excitement surrounding GLP-1 drugs.

If you're investing in the long term, holding shares of Eli Lilly or Novo Nordisk can be a great idea given how much upside these stocks may possess simply due to their highly effective GLP-1 drugs. It wouldn't surprise me if within the next 10 years, both of these stocks rise to valuations beyond $1 trillion as they can be among the best healthcare investments to be hanging on to right now.