No surprise, then, that the demand for these medicines is huge and projected to get even larger as more supply comes on-line and more GLP-1s win Food and Drug Administration approval for weight loss.

But what has gotten less attention is the healthcare crisis that could come as spending on the drugs threatens to overwhelm the insurers, employers, and government programs that buy the country’s medicines. The financial crunch would probably peak from 2025, when Medicare coverage of the medicines might begin, to 2027, when the cost of some of the drugs could start to drop.

Novo Nordisk and Eli Lilly are about to start raking in tens of billions of dollars a year on their new obesity drugs, say Wall Street analysts. That’s great news for the drugmakers, certainly, but it could be a disaster for the companies and government agencies set to pick up the bill.

The new medicines, known as GLP-1 receptor agonists, promise body weight reductions of as much as 20%, and may cut patients’ risk of heart attack or stroke. By all appearances, they’re the most effective safe weight-loss drugs in history.

When the medication hits GLP-1 receptors in different parts of the brain, that triggers a reaction, stimulating nerves that mimic the effect of eating food — people have reduced appetite, and when they do eat, they feel full sooner.

Another way the medication works is that it slows down stomach emptying, which slows down the absorption of calories and may contribute to the feeling of fullness.

Mounjaro contains tirzepatide and also mimics a second hormone, called GIP, which may improve how the body breaks down sugar and fat in addition to reducing appetite, NBC News reported.

All of the medications come with side effects. Common ones include nausea, diarrhea, vomiting, stomach pain and constipation. Possible serious side effects include pancreatitis, kidney problems and other issues.

Doctors are still learning the best way to give patients these medications, and some patients may need another drug when their current one stops working as well, she added.

Most people will need to be on the drugs long-term to maintain their weight-loss, she said, and it's still important to eat a healthy diet while on the treatments.

One of the hottest topics in Hollywood lately is the type 2 diabetes drug Ozempic and its fellow semaglutide, obesity drug Wegovy. The use of either prescription — which Dr. Ania Jastreboff tells PEOPLE are "nutrient-stimulated, hormone-based medications" that target the brain — leads to weight loss, and because of that, some people who don't necessarily need the drugs are using them to slim down.

"The Hollywood trend is concerning," Dr. Caroline Apovian, co-director of the Center for Weight Management and Wellness at the Brigham and Women's Hospital in Boston