March 18, 2026

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Weight loss was just the beginning: How the GLP-1 story is evolving

“Imitation” drugs, unexpected benefits, serious pitfalls—here’s what comes next as GLP-1 medications continue to rise in popularity

By Kendra Pierre-Louis, Lauren J. Young, Sushmita Pathak & Alex Sugiura

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Kendra Pierre-Louis: For Scientific American’s Science Quickly, I’m Kendra Pierre-Louis, in for Rachel Feltman.

In early March the U.S. Food and Drug Administration sent a warning letter to Novo Nordisk, the maker of Ozempic and Wegovy, saying the company had failed to disclose potential risks associated with taking these drugs. The agency alleged that Novo Nordisk failed to properly report and/or follow up on three deaths of individuals who were taking semaglutide, the key ingredient in Ozempic and Wegovy.

The drugs are part of a broader class of medicine known as GLP-1s that have grown wildly popular for everything from type 2 diabetes to weight loss and are increasingly seen as having potential benefits far beyond those two conditions. The popularity of these drugs has led to a sea of GLP-1 offerings flooding the market—not all of them FDA-approved.

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We sat down with Lauren Young, an associate editor covering health and medicine for Scientific American to talk about where GLP-1s go from here.

Pierre-Louis: Thank you for being here, Lauren.

Lauren Young: Thanks so much for having me.

Pierre-Louis: So at a basic level, what is a GLP-1?

Young: Right, so GLP-1 drugs, these are the drugs that you’ve probably heard with those, like, fun advertisement chimes. They’re sold as Wegovy and Ozempic—that is the brand name for the active ingredient semaglutide. And then you’ll probably have also heard of Zepbound and Mounjaro, which are the brand name for tirzepatide. And so these were originally type 2 diabetes treatments, and now they have since moved on to become weight-loss treatments. And the reason why they’re so effective is because they mimic a hormone in the body called GLP-1, glucagonlike peptide 1—fun name.

And so what this hormone does is it, essentially kick-starts insulin production, so that’s why it makes a really great type 2 diabetes medication. But over time researchers also noticed that, “Hey, it looks like people are eating less on this drug.” And they found out that it also influences satiety levels, people feel fuller faster, and you eat less and therefore lose weight. So that’s essentially how the hormone and also the drug works ’cause the drug essentially mimics that hormone.

Pierre-Louis: And my understanding is, is that, in general, in our bodies, GLP-1s are kind of short-acting. But with the drug, they kind of hang out for longer.

Young: Exactly. Yes, yes. So these drug manufacturers have essentially crafted them to withstand and stay in the body longer because there’s enzymes in the body that break down the hormone at much faster rates, so they can last in the body for—stay active, essentially, for about a week.

Pierre-Louis: So there’s been this big kind of tension brewing in recent months about the rise of what we might call imitation GLP-1s, like, the compounded versions. Can you tell me: What is a compounded drug?

Young: Right, so a compounded drug, these are produced by compounded pharmacies. So compounded pharmacies essentially create, like, bespoke medicines for individual clinical use. So people who can’t take an oral medication, for instance, might need that medication transformed into a cream or an IV drip or something like that, or kids, for instance, might need a lower dose. Same with, like, pets and zoo animals, they also sometimes take compounded medications ’cause they, you know, need a specialized recipe for, you know, specific medications.

Pierre-Louis: So, for example, I had an ankle injury a couple years back ...

Young: Yeah.

Pierre-Louis: And my doctor prescribed, like, a bespoke anti-inflammatory lotion for me to put on it ...

Young: Right.

Pierre-Louis: And that was sent to me by a, a compounder.

Young: Yeah, yeah, that’s a, a perfect example of what a compounded drug is. So these compounded pharmacies do fill an important need. But it’s also important to note that no compounded drug is FDA-approved, so that means they aren’t tested or reviewed for safety or effectiveness.

Pierre-Louis: Can you talk a bit about the role that compounding pharmacies have been playing with GLP-1s?

Young: So the story of the compounded GLP-1s goe