“It’s everywhere,” Dr. Razia Hashmi, Blue Cross Blue Shield Association (BCBSA) vice president of clinical affairs, said Tuesday during a town hall at Fortune’s Brainstorm Health conference in Dana Point, Calif. “It’s part of our conversation. It’s on social media, your family’s talking about it, we’re talking about it in the boardroom, we’re talking about it in the break room. There is, obviously, a lot of excitement about it—the adoption’s been exponential—but there is so much more to learn.”

Not all of it is positive, as revealed by a new study conducted by Blue Health Intelligence that examined nearly 170,000 GLP-1 users who were prescribed the medication for weight loss. Released Tuesday, it’s “the largest-ever study done, real-world evidence study” of the medication, Hashmi said.

The study shows patients aren’t taking the medication properly, despite its skyrocketing popularity: Net sales of antiobesity drugs such as semaglutide, or Wegovy, hit $1.1 billion in the second quarter of 2023, per the Congressional Budget Office.

Most patients taking GLP-1 drugs for weight management didn’t stay on their prescribed treatment for the minimum 12 weeks, meaning they were unlikely to attain clinically meaningful weight loss. Young adults (aged 18–34) were more likely to drop out of treatment sooner, and more than 30% of all patients dropped out after just four weeks, before reaching the targeted dose.

The gastrointestinal side effects of GLP-1s, including nausea, vomiting, and diarrhea, may be a reason people don’t complete treatment, the study notes. But because the medication is intended to treat obesity and Type 2 diabetes—both serious, chronic conditions—quitting cold turkey without a doctor’s guidance may be dangerous.

“One has to ask, why?” Hashmi said. One clue, she said, comes from the doctor prescribing the medication: “Your provider matters. If your provider is trained in endocrinology, if they are trained and board-certified in obesity management, the likelihood that you will stay on the treatment is much, much higher.

“The other thing that we found was that each additional visit to your doctor, regardless of specialty, increased your chances of reaching that meaningful weight-loss goal by 60%.”

Another finding Hashmi highlighted was that support for diet, nutrition, behavioral health, and side effect management matters. The same goes for health equity; the study revealed people who lived in underserved health regions were less likely to complete 12 weeks of treatment.

Andrew Nusca, editorial director of Fortune’s Brainstorm conference series, moderated the town hall, which also featured Dr. Rami Bailony, cofounder and CEO of Enara Health. While acknowledging that such research on GLP-1 usage and outcomes is needed, Bailony stressed the drugs should be just one component of obesity management.

“[GLP-1s] will change the way we do care, but ultimately, what matters is the framework in which those are delivered,” he said. “Our mission is to deliver personalized, data-driven treatment, and we do that by integrating directly into primary care and cardiology care, and [it] will be the data layer that personalizes that treatment that’s going to make a difference in the end.”

For more on weight management:

• Zepbound vs. Wegovy: New clinical trial says this weight-loss medication sheds more pounds
• Most Americans who want to lose weight don’t want to take GLP-1 drugs like Wegovy and Zepbound, new survey says
• This is the best time of day to exercise for people living with obesity, new study shows
• An exercise pill may soon offer the same benefits as a workout, scientists say
• Belly fat tied to brain health in middle-aged adults at high risk of Alzheimer’s, study finds—but it’s worse for men