That isn’t surprising, says John Wilding, an obesity researcher at the University of Liverpool who led a major study on the use of semaglutide to treat overweight or obese adults. “Clinical trials tell us about the biology–whether the drug works—and it’s a very highly controlled situation because that’s the way the trials are designed,” he says. People don’t usually have to pay for drugs in clinical trials, and they’re supported with regular check-ins from research staff.
In the real world, there are all kinds of reasons people stop taking drugs. One survey of diabetes patients asked them—and their doctors—why they stopped taking their GLP-1 RA. Patients who quit the drugs cited side effects such as nausea and diarrhea, disliking having to inject themselves regularly, and disappointment that the injections didn’t help them lose weight or control their blood glucose. In the US, almost half of patients who stopped taking a GLP-1 RA cited high costs as a reason. We know that patients in the US who have higher insurance copayments are less likely to stick with their diabetes medicine. “These drugs are wildly expensive, especially the weekly ones,” says William Polonsky, president of the Behavioural Diabetes Institute in California. The list price for a monthly dose of Wegovy is almost $1,350, although some insurers cover at least part of that hefty cost.
If these patterns hold true for the drugs as they are used for weight loss—and that’s still a big “if” at the moment—then maybe we shouldn’t expect that everyone who starts taking Wegovy or similar drugs will stay on them forever. The UK’s National Institute for Health and Care Excellence, which decides which drugs should be available through the National Health Service (NHS), recommends a two-year cap on how long someone can be prescribed Wegovy for weight loss. It’s possible, Wilding says, that some people will stop taking the drug after they’ve lost a certain amount of weight and opt to manage their health through diet and exercise instead.
We already know that when people stop taking semaglutide, they regain most of the weight they lost during the treatment. This raises an important question. If people regain their lost weight, are they still healthier in the long run than someone who never lost the weight in the first place?
For semaglutide, the short answer is that we don’t know. But there is some intriguing data that suggests dietary interventions can have lasting benefits long after they’ve been dropped. In 1986, nearly 440 prediabetic people in the Chinese city of Da Qing were assigned to a trial in which they were encouraged to follow a healthier diet, exercise, or a combination of the two for six years. The control group was asked to continue their lifestyle as normal. Thirty years later, scientists returned to the people who had taken part in the study and found that those in the diet and exercise groups had later diabetes onset and less cardiovascular disease than people in the control group.